Commit Graph

284 Commits

Author SHA1 Message Date
Linus Torvalds
0f25f0e4ef the bulk of struct fd memory safety stuff
Making sure that struct fd instances are destroyed in the same
 scope where they'd been created, getting rid of reassignments
 and passing them by reference, converting to CLASS(fd{,_pos,_raw}).
 
 We are getting very close to having the memory safety of that stuff
 trivial to verify.
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull 'struct fd' class updates from Al Viro:
 "The bulk of struct fd memory safety stuff

  Making sure that struct fd instances are destroyed in the same scope
  where they'd been created, getting rid of reassignments and passing
  them by reference, converting to CLASS(fd{,_pos,_raw}).

  We are getting very close to having the memory safety of that stuff
  trivial to verify"

* tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits)
  deal with the last remaing boolean uses of fd_file()
  css_set_fork(): switch to CLASS(fd_raw, ...)
  memcg_write_event_control(): switch to CLASS(fd)
  assorted variants of irqfd setup: convert to CLASS(fd)
  do_pollfd(): convert to CLASS(fd)
  convert do_select()
  convert vfs_dedupe_file_range().
  convert cifs_ioctl_copychunk()
  convert media_request_get_by_fd()
  convert spu_run(2)
  switch spufs_calls_{get,put}() to CLASS() use
  convert cachestat(2)
  convert do_preadv()/do_pwritev()
  fdget(), more trivial conversions
  fdget(), trivial conversions
  privcmd_ioeventfd_assign(): don't open-code eventfd_ctx_fdget()
  o2hb_region_dev_store(): avoid goto around fdget()/fdput()
  introduce "fd_pos" class, convert fdget_pos() users to it.
  fdget_raw() users: switch to CLASS(fd_raw)
  convert vmsplice() to CLASS(fd)
  ...
2024-11-18 12:24:06 -08:00
Linus Torvalds
4c797b11a8 vfs-6.13.file
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Merge tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs file updates from Christian Brauner:
 "This contains changes the changes for files for this cycle:

   - Introduce a new reference counting mechanism for files.

     As atomic_inc_not_zero() is implemented with a try_cmpxchg() loop
     it has O(N^2) behaviour under contention with N concurrent
     operations and it is in a hot path in __fget_files_rcu().

     The rcuref infrastructures remedies this problem by using an
     unconditional increment relying on safe- and dead zones to make
     this work and requiring rcu protection for the data structure in
     question. This not just scales better it also introduces overflow
     protection.

     However, in contrast to generic rcuref, files require a memory
     barrier and thus cannot rely on *_relaxed() atomic operations and
     also require to be built on atomic_long_t as having massive amounts
     of reference isn't unheard of even if it is just an attack.

     This adds a file specific variant instead of making this a generic
     library.

     This has been tested by various people and it gives consistent
     improvement up to 3-5% on workloads with loads of threads.

   - Add a fastpath for find_next_zero_bit(). Skip 2-levels searching
     via find_next_zero_bit() when there is a free slot in the word that
     contains the next fd. This improves pts/blogbench-1.1.0 read by 8%
     and write by 4% on Intel ICX 160.

   - Conditionally clear full_fds_bits since it's very likely that a bit
     in full_fds_bits has been cleared during __clear_open_fds(). This
     improves pts/blogbench-1.1.0 read up to 13%, and write up to 5% on
     Intel ICX 160.

   - Get rid of all lookup_*_fdget_rcu() variants. They were used to
     lookup files without taking a reference count. That became invalid
     once files were switched to SLAB_TYPESAFE_BY_RCU and now we're
     always taking a reference count. Switch to an already existing
     helper and remove the legacy variants.

   - Remove pointless includes of <linux/fdtable.h>.

   - Avoid cmpxchg() in close_files() as nobody else has a reference to
     the files_struct at that point.

   - Move close_range() into fs/file.c and fold __close_range() into it.

   - Cleanup calling conventions of alloc_fdtable() and expand_files().

   - Merge __{set,clear}_close_on_exec() into one.

   - Make __set_open_fd() set cloexec as well instead of doing it in two
     separate steps"

* tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  selftests: add file SLAB_TYPESAFE_BY_RCU recycling stressor
  fs: port files to file_ref
  fs: add file_ref
  expand_files(): simplify calling conventions
  make __set_open_fd() set cloexec state as well
  fs: protect backing files with rcu
  file.c: merge __{set,clear}_close_on_exec()
  alloc_fdtable(): change calling conventions.
  fs/file.c: add fast path in find_next_fd()
  fs/file.c: conditionally clear full_fds
  fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd()
  move close_range(2) into fs/file.c, fold __close_range() into it
  close_files(): don't bother with xchg()
  remove pointless includes of <linux/fdtable.h>
  get rid of ...lookup...fdget_rcu() family
2024-11-18 10:30:29 -08:00
Al Viro
8152f82010 fdget(), more trivial conversions
all failure exits prior to fdget() leave the scope, all matching fdput()
are immediately followed by leaving the scope.

[xfs_ioc_commit_range() chunk moved here as well]

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-11-03 01:28:06 -05:00
Al Viro
6348be02ee fdget(), trivial conversions
fdget() is the first thing done in scope, all matching fdput() are
immediately followed by leaving the scope.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-11-03 01:28:06 -05:00
Christian Brauner
90ee6ed776
fs: port files to file_ref
Port files to rely on file_ref reference to improve scaling and gain
overflow protection.

- We continue to WARN during get_file() in case a file that is already
  marked dead is revived as get_file() is only valid if the caller
  already holds a reference to the file. This hasn't changed just the
  check changes.

- The semantics for epoll and ttm's dmabuf usage have changed. Both
  epoll and ttm synchronize with __fput() to prevent the underlying file
  from beeing freed.

  (1) epoll

      Explaining epoll is straightforward using a simple diagram.
      Essentially, the mutex of the epoll instance needs to be taken in both
      __fput() and around epi_fget() preventing the file from being freed
      while it is polled or preventing the file from being resurrected.

          CPU1                                   CPU2
          fput(file)
          -> __fput(file)
             -> eventpoll_release(file)
                -> eventpoll_release_file(file)
                                                 mutex_lock(&ep->mtx)
                                                 epi_item_poll()
                                                 -> epi_fget()
                                                    -> file_ref_get(file)
                                                 mutex_unlock(&ep->mtx)
                   mutex_lock(&ep->mtx);
                   __ep_remove()
                   mutex_unlock(&ep->mtx);
             -> kmem_cache_free(file)

  (2) ttm dmabuf

      This explanation is a bit more involved. A regular dmabuf file stashed
      the dmabuf in file->private_data and the file in dmabuf->file:

          file->private_data = dmabuf;
          dmabuf->file = file;

      The generic release method of a dmabuf file handles file specific
      things:

          f_op->release::dma_buf_file_release()

      while the generic dentry release method of a dmabuf handles dmabuf
      freeing including driver specific things:

          dentry->d_release::dma_buf_release()

      During ttm dmabuf initialization in ttm_object_device_init() the ttm
      driver copies the provided struct dma_buf_ops into a private location:

          struct ttm_object_device {
                  spinlock_t object_lock;
                  struct dma_buf_ops ops;
                  void (*dmabuf_release)(struct dma_buf *dma_buf);
                  struct idr idr;
          };

          ttm_object_device_init(const struct dma_buf_ops *ops)
          {
                  // copy original dma_buf_ops in private location
                  tdev->ops = *ops;

                  // stash the release method of the original struct dma_buf_ops
                  tdev->dmabuf_release = tdev->ops.release;

                  // override the release method in the copy of the struct dma_buf_ops
                  // with ttm's own dmabuf release method
                  tdev->ops.release = ttm_prime_dmabuf_release;
          }

      When a new dmabuf is created the struct dma_buf_ops with the overriden
      release method set to ttm_prime_dmabuf_release is passed in exp_info.ops:

          DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
          exp_info.ops = &tdev->ops;
          exp_info.size = prime->size;
          exp_info.flags = flags;
          exp_info.priv = prime;

      The call to dma_buf_export() then sets

          mutex_lock_interruptible(&prime->mutex);
          dma_buf = dma_buf_export(&exp_info)
          {
                  dmabuf->ops = exp_info->ops;
          }
          mutex_unlock(&prime->mutex);

      which creates a new dmabuf file and then install a file descriptor to
      it in the callers file descriptor table:

          ret = dma_buf_fd(dma_buf, flags);

      When that dmabuf file is closed we now get:

          fput(file)
          -> __fput(file)
             -> f_op->release::dma_buf_file_release()
             -> dput()
                -> d_op->d_release::dma_buf_release()
                   -> dmabuf->ops->release::ttm_prime_dmabuf_release()
                      mutex_lock(&prime->mutex);
                      if (prime->dma_buf == dma_buf)
                            prime->dma_buf = NULL;
                      mutex_unlock(&prime->mutex);

      Where we can see that prime->dma_buf is set to NULL. So when we have
      the following diagram:

          CPU1                                                          CPU2
          fput(file)
          -> __fput(file)
             -> f_op->release::dma_buf_file_release()
             -> dput()
                -> d_op->d_release::dma_buf_release()
                   -> dmabuf->ops->release::ttm_prime_dmabuf_release()
                                                                        ttm_prime_handle_to_fd()
                                                                        mutex_lock_interruptible(&prime->mutex)
                                                                        dma_buf = prime->dma_buf
                                                                        dma_buf && get_dma_buf_unless_doomed(dma_buf)
                                                                        -> file_ref_get(dma_buf->file)
                                                                        mutex_unlock(&prime->mutex);

                      mutex_lock(&prime->mutex);
                      if (prime->dma_buf == dma_buf)
                            prime->dma_buf = NULL;
                      mutex_unlock(&prime->mutex);
             -> kmem_cache_free(file)

      The logic of the mechanism is the same as for epoll: sync with
      __fput() preventing the file from being freed. Here the
      synchronization happens through the ttm instance's prime->mutex.
      Basically, the lifetime of the dma_buf and the file are tighly
      coupled.

  Both (1) and (2) used to call atomic_inc_not_zero() to check whether
  the file has already been marked dead and then refuse to revive it.

  This is only safe because both (1) and (2) sync with __fput() and thus
  prevent kmem_cache_free() on the file being called and thus prevent
  the file from being immediately recycled due to SLAB_TYPESAFE_BY_RCU.

  Both (1) and (2) have been ported from atomic_inc_not_zero() to
  file_ref_get(). That means a file that is already in the process of
  being marked as FILE_REF_DEAD:

  file_ref_put()
  cnt = atomic_long_dec_return()
  -> __file_ref_put(cnt)
     if (cnt == FIlE_REF_NOREF)
             atomic_long_try_cmpxchg_release(cnt, FILE_REF_DEAD)

  can be revived again:

  CPU1                                                             CPU2
  file_ref_put()
  cnt = atomic_long_dec_return()
  -> __file_ref_put(cnt)
     if (cnt == FIlE_REF_NOREF)
                                                                   file_ref_get()
                                                                   // Brings reference back to FILE_REF_ONEREF
                                                                   atomic_long_add_negative()
             atomic_long_try_cmpxchg_release(cnt, FILE_REF_DEAD)

  This is fine and inherent to the file_ref_get()/file_ref_put()
  semantics. For both (1) and (2) this is safe because __fput() is
  prevented from making progress if file_ref_get() fails due to the
  aforementioned synchronization mechanisms.

  Two cases need to be considered that affect both (1) epoll and (2) ttm
  dmabuf:

   (i) fput()'s file_ref_put() and marks the file as FILE_REF_NOREF but
       before that fput() can mark the file as FILE_REF_DEAD someone
       manages to sneak in a file_ref_get() and brings the refcount back
       from FILE_REF_NOREF to FILE_REF_ONEREF. In that case the original
       fput() doesn't call __fput(). For epoll the poll will finish and
       for ttm dmabuf the file can be used again. For ttm dambuf this is
       actually an advantage because it avoids immediately allocating
       a new dmabuf object.

       CPU1                                                             CPU2
       file_ref_put()
       cnt = atomic_long_dec_return()
       -> __file_ref_put(cnt)
          if (cnt == FIlE_REF_NOREF)
                                                                        file_ref_get()
                                                                        // Brings reference back to FILE_REF_ONEREF
                                                                        atomic_long_add_negative()
                  atomic_long_try_cmpxchg_release(cnt, FILE_REF_DEAD)

  (ii) fput()'s file_ref_put() marks the file FILE_REF_NOREF and
       also suceeds in actually marking it FILE_REF_DEAD and then calls
       into __fput() to free the file.

       When either (1) or (2) call file_ref_get() they fail as
       atomic_long_add_negative() will return true.

       At the same time, both (1) and (2) all file_ref_get() under
       mutexes that __fput() must also acquire preventing
       kmem_cache_free() from freeing the file.

  So while this might be treated as a change in semantics for (1) and
  (2) it really isn't. It if should end up causing issues this can be
  fixed by adding a helper that does something like:

  long cnt = atomic_long_read(&ref->refcnt);
  do {
          if (cnt < 0)
                  return false;
  } while (!atomic_long_try_cmpxchg(&ref->refcnt, &cnt, cnt + 1));
  return true;

  which would block FILE_REF_NOREF to FILE_REF_ONEREF transitions.

- Jann correctly pointed out that kmem_cache_zalloc() cannot be used
  anymore once files have been ported to file_ref_t.

  The kmem_cache_zalloc() call will memset() the whole struct file to
  zero when it is reallocated. This will also set file->f_ref to zero
  which mens that a concurrent file_ref_get() can return true:

  CPU1                            CPU2
                                  __get_file_rcu()
                                    rcu_dereference_raw()
  close()
    [frees file]
  alloc_empty_file()
    kmem_cache_zalloc()
      [reallocates same file]
      memset(..., 0, ...)
                                    file_ref_get()
                                      [increments 0->1, returns true]
    init_file()
      file_ref_init(..., 1)
        [sets to 0]
                                    rcu_dereference_raw()
                                    fput()
                                      file_ref_put()
                                        [decrements 0->FILE_REF_NOREF, frees file]
    [UAF]

   causing a concurrent __get_file_rcu() call to acquire a reference to
   the file that is about to be reallocated and immediately freeing it
   on realizing that it has been recycled. This causes a UAF for the
   task that reallocated/recycled the file.

   This is prevented by switching from kmem_cache_zalloc() to
   kmem_cache_alloc() and initializing the fields manually. With
   file->f_ref initialized last.

   Note that a memset() also isn't guaranteed to atomically update an
   unsigned long so it's theoretically possible to see torn and
   therefore bogus counter values.

Link: https://lore.kernel.org/r/20241007-brauner-file-rcuref-v2-3-387e24dc9163@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-30 09:57:43 +01:00
Xuewen Yan
900bbaae67
epoll: Add synchronous wakeup support for ep_poll_callback
Now, the epoll only use wake_up() interface to wake up task.
However, sometimes, there are epoll users which want to use
the synchronous wakeup flag to hint the scheduler, such as
Android binder driver.
So add a wake_up_sync() define, and use the wake_up_sync()
when the sync is true in ep_poll_callback().

Co-developed-by: Jing Xia <jing.xia@unisoc.com>
Signed-off-by: Jing Xia <jing.xia@unisoc.com>
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Link: https://lore.kernel.org/r/20240426080548.8203-1-xuewen.yan@unisoc.com
Tested-by: Brian Geffon <bgeffon@google.com>
Reviewed-by: Brian Geffon <bgeffon@google.com>
Reported-by: Benoit Lize <lizeb@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-22 11:16:59 +02:00
Christian Brauner
6474353a5e
epoll: annotate racy check
Epoll relies on a racy fastpath check during __fput() in
eventpoll_release() to avoid the hit of pointlessly acquiring a
semaphore. Annotate that race by using WRITE_ONCE() and READ_ONCE().

Link: https://lore.kernel.org/r/66edfb3c.050a0220.3195df.001a.GAE@google.com
Link: https://lore.kernel.org/r/20240925-fungieren-anbauen-79b334b00542@brauner
Reviewed-by: Jan Kara <jack@suse.cz>
Reported-by: syzbot+3b6b32dc50537a49bb4a@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-22 11:16:56 +02:00
Linus Torvalds
f8ffbc365f struct fd layout change (and conversion to accessor helpers)
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Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull 'struct fd' updates from Al Viro:
 "Just the 'struct fd' layout change, with conversion to accessor
  helpers"

* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  add struct fd constructors, get rid of __to_fd()
  struct fd: representation change
  introduce fd_file(), convert all accessors to it.
2024-09-23 09:35:36 -07:00
Martin Karsten
b9ca079dd6 eventpoll: Annotate data-race of busy_poll_usecs
A struct eventpoll's busy_poll_usecs field can be modified via a user
ioctl at any time. All reads of this field should be annotated with
READ_ONCE.

Fixes: 85455c795c ("eventpoll: support busy poll per epoll instance")
Cc: stable@vger.kernel.org
Signed-off-by: Martin Karsten <mkarsten@uwaterloo.ca>
Link: https://lore.kernel.org/r/20240806123301.167557-1-jdamato@fastly.com
Reviewed-by: Joe Damato <jdamato@fastly.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:34 +02:00
Joe Damato
4f98f380f4 eventpoll: Don't re-zero eventpoll fields
Remove redundant and unnecessary code.

ep_alloc uses kzalloc to create struct eventpoll, so there is no need to
set fields to defaults of 0. This was accidentally introduced in commit
85455c795c ("eventpoll: support busy poll per epoll instance") and
expanded on in follow-up commits.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Link: https://lore.kernel.org/r/20240807105231.179158-1-jdamato@fastly.com
Reviewed-by: Martin Karsten <mkarsten@uwaterloo.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:34 +02:00
Al Viro
1da91ea87a introduce fd_file(), convert all accessors to it.
For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
	Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
	This commit converts (almost) all of f.file to
fd_file(f).  It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).

	NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).

[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-08-12 22:00:43 -04:00
Linus Torvalds
4efaa5acf0 epoll: be better about file lifetimes
epoll can call out to vfs_poll() with a file pointer that may race with
the last 'fput()'. That would make f_count go down to zero, and while
the ep->mtx locking means that the resulting file pointer tear-down will
be blocked until the poll returns, it means that f_count is already
dead, and any use of it won't actually get a reference to the file any
more: it's dead regardless.

Make sure we have a valid ref on the file pointer before we call down to
vfs_poll() from the epoll routines.

Link: https://lore.kernel.org/lkml/0000000000002d631f0615918f1e@google.com/
Reported-by: syzbot+045b454ab35fd82a35fb@syzkaller.appspotmail.com
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-05-05 14:00:48 -07:00
Linus Torvalds
9187210eee Networking changes for 6.9.
Core & protocols
 ----------------
 
  - Large effort by Eric to lower rtnl_lock pressure and remove locks:
 
    - Make commonly used parts of rtnetlink (address, route dumps etc.)
      lockless, protected by RCU instead of rtnl_lock.
 
    - Add a netns exit callback which already holds rtnl_lock,
      allowing netns exit to take rtnl_lock once in the core
      instead of once for each driver / callback.
 
    - Remove locks / serialization in the socket diag interface.
 
    - Remove 6 calls to synchronize_rcu() while holding rtnl_lock.
 
    - Remove the dev_base_lock, depend on RCU where necessary.
 
  - Support busy polling on a per-epoll context basis. Poll length
    and budget parameters can be set independently of system defaults.
 
  - Introduce struct net_hotdata, to make sure read-mostly global config
    variables fit in as few cache lines as possible.
 
  - Add optional per-nexthop statistics to ease monitoring / debug
    of ECMP imbalance problems.
 
  - Support TCP_NOTSENT_LOWAT in MPTCP.
 
  - Ensure that IPv6 temporary addresses' preferred lifetimes are long
    enough, compared to other configured lifetimes, and at least 2 sec.
 
  - Support forwarding of ICMP Error messages in IPSec, per RFC 4301.
 
  - Add support for the independent control state machine for bonding
    per IEEE 802.1AX-2008 5.4.15 in addition to the existing coupled
    control state machine.
 
  - Add "network ID" to MCTP socket APIs to support hosts with multiple
    disjoint MCTP networks.
 
  - Re-use the mono_delivery_time skbuff bit for packets which user
    space wants to be sent at a specified time. Maintain the timing
    information while traversing veth links, bridge etc.
 
  - Take advantage of MSG_SPLICE_PAGES for RxRPC DATA and ACK packets.
 
  - Simplify many places iterating over netdevs by using an xarray
    instead of a hash table walk (hash table remains in place, for
    use on fastpaths).
 
  - Speed up scanning for expired routes by keeping a dedicated list.
 
  - Speed up "generic" XDP by trying harder to avoid large allocations.
 
  - Support attaching arbitrary metadata to netconsole messages.
 
 Things we sprinkled into general kernel code
 --------------------------------------------
 
  - Enforce VM_IOREMAP flag and range in ioremap_page_range and introduce
    VM_SPARSE kind and vm_area_[un]map_pages (used by bpf_arena).
 
  - Rework selftest harness to enable the use of the full range of
    ksft exit code (pass, fail, skip, xfail, xpass).
 
 Netfilter
 ---------
 
  - Allow userspace to define a table that is exclusively owned by a daemon
    (via netlink socket aliveness) without auto-removing this table when
    the userspace program exits. Such table gets marked as orphaned and
    a restarting management daemon can re-attach/regain ownership.
 
  - Speed up element insertions to nftables' concatenated-ranges set type.
    Compact a few related data structures.
 
 BPF
 ---
 
  - Add BPF token support for delegating a subset of BPF subsystem
    functionality from privileged system-wide daemons such as systemd
    through special mount options for userns-bound BPF fs to a trusted
    & unprivileged application.
 
  - Introduce bpf_arena which is sparse shared memory region between BPF
    program and user space where structures inside the arena can have
    pointers to other areas of the arena, and pointers work seamlessly
    for both user-space programs and BPF programs.
 
  - Introduce may_goto instruction that is a contract between the verifier
    and the program. The verifier allows the program to loop assuming it's
    behaving well, but reserves the right to terminate it.
 
  - Extend the BPF verifier to enable static subprog calls in spin lock
    critical sections.
 
  - Support registration of struct_ops types from modules which helps
    projects like fuse-bpf that seeks to implement a new struct_ops type.
 
  - Add support for retrieval of cookies for perf/kprobe multi links.
 
  - Support arbitrary TCP SYN cookie generation / validation in the TC
    layer with BPF to allow creating SYN flood handling in BPF firewalls.
 
  - Add code generation to inline the bpf_kptr_xchg() helper which
    improves performance when stashing/popping the allocated BPF objects.
 
 Wireless
 --------
 
  - Add SPP (signaling and payload protected) AMSDU support.
 
  - Support wider bandwidth OFDMA, as required for EHT operation.
 
 Driver API
 ----------
 
  - Major overhaul of the Energy Efficient Ethernet internals to support
    new link modes (2.5GE, 5GE), share more code between drivers
    (especially those using phylib), and encourage more uniform behavior.
    Convert and clean up drivers.
 
  - Define an API for querying per netdev queue statistics from drivers.
 
  - IPSec: account in global stats for fully offloaded sessions.
 
  - Create a concept of Ethernet PHY Packages at the Device Tree level,
    to allow parameterizing the existing PHY package code.
 
  - Enable Rx hashing (RSS) on GTP protocol fields.
 
 Misc
 ----
 
  - Improvements and refactoring all over networking selftests.
 
  - Create uniform module aliases for TC classifiers, actions,
    and packet schedulers to simplify creating modprobe policies.
 
  - Address all missing MODULE_DESCRIPTION() warnings in networking.
 
  - Extend the Netlink descriptions in YAML to cover message encapsulation
    or "Netlink polymorphism", where interpretation of nested attributes
    depends on link type, classifier type or some other "class type".
 
 Drivers
 -------
 
  - Ethernet high-speed NICs:
    - Add a new driver for Marvell's Octeon PCI Endpoint NIC VF.
    - Intel (100G, ice, idpf):
      - support E825-C devices
    - nVidia/Mellanox:
      - support devices with one port and multiple PCIe links
    - Broadcom (bnxt):
      - support n-tuple filters
      - support configuring the RSS key
    - Wangxun (ngbe/txgbe):
      - implement irq_domain for TXGBE's sub-interrupts
    - Pensando/AMD:
      - support XDP
      - optimize queue submission and wakeup handling (+17% bps)
      - optimize struct layout, saving 28% of memory on queues
 
  - Ethernet NICs embedded and virtual:
    - Google cloud vNIC:
      - refactor driver to perform memory allocations for new queue
        config before stopping and freeing the old queue memory
    - Synopsys (stmmac):
      - obey queueMaxSDU and implement counters required by 802.1Qbv
    - Renesas (ravb):
      - support packet checksum offload
      - suspend to RAM and runtime PM support
 
  - Ethernet switches:
    - nVidia/Mellanox:
      - support for nexthop group statistics
    - Microchip:
      - ksz8: implement PHY loopback
      - add support for KSZ8567, a 7-port 10/100Mbps switch
 
  - PTP:
    - New driver for RENESAS FemtoClock3 Wireless clock generator.
    - Support OCP PTP cards designed and built by Adva.
 
  - CAN:
    - Support recvmsg() flags for own, local and remote traffic
      on CAN BCM sockets.
    - Support for esd GmbH PCIe/402 CAN device family.
    - m_can:
      - Rx/Tx submission coalescing
      - wake on frame Rx
 
  - WiFi:
    - Intel (iwlwifi):
      - enable signaling and payload protected A-MSDUs
      - support wider-bandwidth OFDMA
      - support for new devices
      - bump FW API to 89 for AX devices; 90 for BZ/SC devices
    - MediaTek (mt76):
      - mt7915: newer ADIE version support
      - mt7925: radio temperature sensor support
    - Qualcomm (ath11k):
      - support 6 GHz station power modes: Low Power Indoor (LPI),
        Standard Power) SP and Very Low Power (VLP)
      - QCA6390 & WCN6855: support 2 concurrent station interfaces
      - QCA2066 support
    - Qualcomm (ath12k):
      - refactoring in preparation for Multi-Link Operation (MLO) support
      - 1024 Block Ack window size support
      - firmware-2.bin support
      - support having multiple identical PCI devices (firmware needs to
        have ATH12K_FW_FEATURE_MULTI_QRTR_ID)
      - QCN9274: support split-PHY devices
      - WCN7850: enable Power Save Mode in station mode
      - WCN7850: P2P support
    - RealTek:
      - rtw88: support for more rtw8811cu and rtw8821cu devices
      - rtw89: support SCAN_RANDOM_SN and SET_SCAN_DWELL
      - rtlwifi: speed up USB firmware initialization
      - rtwl8xxxu:
        - RTL8188F: concurrent interface support
        - Channel Switch Announcement (CSA) support in AP mode
    - Broadcom (brcmfmac):
      - per-vendor feature support
      - per-vendor SAE password setup
      - DMI nvram filename quirk for ACEPC W5 Pro
 
 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Jakub Kicinski:
 "Core & protocols:

   - Large effort by Eric to lower rtnl_lock pressure and remove locks:

      - Make commonly used parts of rtnetlink (address, route dumps
        etc) lockless, protected by RCU instead of rtnl_lock.

      - Add a netns exit callback which already holds rtnl_lock,
        allowing netns exit to take rtnl_lock once in the core instead
        of once for each driver / callback.

      - Remove locks / serialization in the socket diag interface.

      - Remove 6 calls to synchronize_rcu() while holding rtnl_lock.

      - Remove the dev_base_lock, depend on RCU where necessary.

   - Support busy polling on a per-epoll context basis. Poll length and
     budget parameters can be set independently of system defaults.

   - Introduce struct net_hotdata, to make sure read-mostly global
     config variables fit in as few cache lines as possible.

   - Add optional per-nexthop statistics to ease monitoring / debug of
     ECMP imbalance problems.

   - Support TCP_NOTSENT_LOWAT in MPTCP.

   - Ensure that IPv6 temporary addresses' preferred lifetimes are long
     enough, compared to other configured lifetimes, and at least 2 sec.

   - Support forwarding of ICMP Error messages in IPSec, per RFC 4301.

   - Add support for the independent control state machine for bonding
     per IEEE 802.1AX-2008 5.4.15 in addition to the existing coupled
     control state machine.

   - Add "network ID" to MCTP socket APIs to support hosts with multiple
     disjoint MCTP networks.

   - Re-use the mono_delivery_time skbuff bit for packets which user
     space wants to be sent at a specified time. Maintain the timing
     information while traversing veth links, bridge etc.

   - Take advantage of MSG_SPLICE_PAGES for RxRPC DATA and ACK packets.

   - Simplify many places iterating over netdevs by using an xarray
     instead of a hash table walk (hash table remains in place, for use
     on fastpaths).

   - Speed up scanning for expired routes by keeping a dedicated list.

   - Speed up "generic" XDP by trying harder to avoid large allocations.

   - Support attaching arbitrary metadata to netconsole messages.

  Things we sprinkled into general kernel code:

   - Enforce VM_IOREMAP flag and range in ioremap_page_range and
     introduce VM_SPARSE kind and vm_area_[un]map_pages (used by
     bpf_arena).

   - Rework selftest harness to enable the use of the full range of ksft
     exit code (pass, fail, skip, xfail, xpass).

  Netfilter:

   - Allow userspace to define a table that is exclusively owned by a
     daemon (via netlink socket aliveness) without auto-removing this
     table when the userspace program exits. Such table gets marked as
     orphaned and a restarting management daemon can re-attach/regain
     ownership.

   - Speed up element insertions to nftables' concatenated-ranges set
     type. Compact a few related data structures.

  BPF:

   - Add BPF token support for delegating a subset of BPF subsystem
     functionality from privileged system-wide daemons such as systemd
     through special mount options for userns-bound BPF fs to a trusted
     & unprivileged application.

   - Introduce bpf_arena which is sparse shared memory region between
     BPF program and user space where structures inside the arena can
     have pointers to other areas of the arena, and pointers work
     seamlessly for both user-space programs and BPF programs.

   - Introduce may_goto instruction that is a contract between the
     verifier and the program. The verifier allows the program to loop
     assuming it's behaving well, but reserves the right to terminate
     it.

   - Extend the BPF verifier to enable static subprog calls in spin lock
     critical sections.

   - Support registration of struct_ops types from modules which helps
     projects like fuse-bpf that seeks to implement a new struct_ops
     type.

   - Add support for retrieval of cookies for perf/kprobe multi links.

   - Support arbitrary TCP SYN cookie generation / validation in the TC
     layer with BPF to allow creating SYN flood handling in BPF
     firewalls.

   - Add code generation to inline the bpf_kptr_xchg() helper which
     improves performance when stashing/popping the allocated BPF
     objects.

  Wireless:

   - Add SPP (signaling and payload protected) AMSDU support.

   - Support wider bandwidth OFDMA, as required for EHT operation.

  Driver API:

   - Major overhaul of the Energy Efficient Ethernet internals to
     support new link modes (2.5GE, 5GE), share more code between
     drivers (especially those using phylib), and encourage more
     uniform behavior. Convert and clean up drivers.

   - Define an API for querying per netdev queue statistics from
     drivers.

   - IPSec: account in global stats for fully offloaded sessions.

   - Create a concept of Ethernet PHY Packages at the Device Tree level,
     to allow parameterizing the existing PHY package code.

   - Enable Rx hashing (RSS) on GTP protocol fields.

  Misc:

   - Improvements and refactoring all over networking selftests.

   - Create uniform module aliases for TC classifiers, actions, and
     packet schedulers to simplify creating modprobe policies.

   - Address all missing MODULE_DESCRIPTION() warnings in networking.

   - Extend the Netlink descriptions in YAML to cover message
     encapsulation or "Netlink polymorphism", where interpretation of
     nested attributes depends on link type, classifier type or some
     other "class type".

  Drivers:

   - Ethernet high-speed NICs:
      - Add a new driver for Marvell's Octeon PCI Endpoint NIC VF.
      - Intel (100G, ice, idpf):
         - support E825-C devices
      - nVidia/Mellanox:
         - support devices with one port and multiple PCIe links
      - Broadcom (bnxt):
         - support n-tuple filters
         - support configuring the RSS key
      - Wangxun (ngbe/txgbe):
         - implement irq_domain for TXGBE's sub-interrupts
      - Pensando/AMD:
         - support XDP
         - optimize queue submission and wakeup handling (+17% bps)
         - optimize struct layout, saving 28% of memory on queues

   - Ethernet NICs embedded and virtual:
      - Google cloud vNIC:
         - refactor driver to perform memory allocations for new queue
           config before stopping and freeing the old queue memory
      - Synopsys (stmmac):
         - obey queueMaxSDU and implement counters required by 802.1Qbv
      - Renesas (ravb):
         - support packet checksum offload
         - suspend to RAM and runtime PM support

   - Ethernet switches:
      - nVidia/Mellanox:
         - support for nexthop group statistics
      - Microchip:
         - ksz8: implement PHY loopback
         - add support for KSZ8567, a 7-port 10/100Mbps switch

   - PTP:
      - New driver for RENESAS FemtoClock3 Wireless clock generator.
      - Support OCP PTP cards designed and built by Adva.

   - CAN:
      - Support recvmsg() flags for own, local and remote traffic on CAN
        BCM sockets.
      - Support for esd GmbH PCIe/402 CAN device family.
      - m_can:
         - Rx/Tx submission coalescing
         - wake on frame Rx

   - WiFi:
      - Intel (iwlwifi):
         - enable signaling and payload protected A-MSDUs
         - support wider-bandwidth OFDMA
         - support for new devices
         - bump FW API to 89 for AX devices; 90 for BZ/SC devices
      - MediaTek (mt76):
         - mt7915: newer ADIE version support
         - mt7925: radio temperature sensor support
      - Qualcomm (ath11k):
         - support 6 GHz station power modes: Low Power Indoor (LPI),
           Standard Power) SP and Very Low Power (VLP)
         - QCA6390 & WCN6855: support 2 concurrent station interfaces
         - QCA2066 support
      - Qualcomm (ath12k):
         - refactoring in preparation for Multi-Link Operation (MLO)
           support
         - 1024 Block Ack window size support
         - firmware-2.bin support
         - support having multiple identical PCI devices (firmware needs
           to have ATH12K_FW_FEATURE_MULTI_QRTR_ID)
         - QCN9274: support split-PHY devices
         - WCN7850: enable Power Save Mode in station mode
         - WCN7850: P2P support
      - RealTek:
         - rtw88: support for more rtw8811cu and rtw8821cu devices
         - rtw89: support SCAN_RANDOM_SN and SET_SCAN_DWELL
         - rtlwifi: speed up USB firmware initialization
         - rtwl8xxxu:
             - RTL8188F: concurrent interface support
             - Channel Switch Announcement (CSA) support in AP mode
      - Broadcom (brcmfmac):
         - per-vendor feature support
         - per-vendor SAE password setup
         - DMI nvram filename quirk for ACEPC W5 Pro"

* tag 'net-next-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2255 commits)
  nexthop: Fix splat with CONFIG_DEBUG_PREEMPT=y
  nexthop: Fix out-of-bounds access during attribute validation
  nexthop: Only parse NHA_OP_FLAGS for dump messages that require it
  nexthop: Only parse NHA_OP_FLAGS for get messages that require it
  bpf: move sleepable flag from bpf_prog_aux to bpf_prog
  bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()
  selftests/bpf: Add kprobe multi triggering benchmarks
  ptp: Move from simple ida to xarray
  vxlan: Remove generic .ndo_get_stats64
  vxlan: Do not alloc tstats manually
  devlink: Add comments to use netlink gen tool
  nfp: flower: handle acti_netdevs allocation failure
  net/packet: Add getsockopt support for PACKET_COPY_THRESH
  net/netlink: Add getsockopt support for NETLINK_LISTEN_ALL_NSID
  selftests/bpf: Add bpf_arena_htab test.
  selftests/bpf: Add bpf_arena_list test.
  selftests/bpf: Add unit tests for bpf_arena_alloc/free_pages
  bpf: Add helper macro bpf_addr_space_cast()
  libbpf: Recognize __arena global variables.
  bpftool: Recognize arena map type
  ...
2024-03-12 17:44:08 -07:00
Dmitry Antipov
0611a640e6 eventpoll: prefer kfree_rcu() in __ep_remove()
In '__ep_remove()', prefer 'kfree_rcu()' over 'call_rcu()' with
dummy 'epi_rcu_free()' callback. This follows commit d0089603fa
("fs: prefer kfree_rcu() in fasync_remove_entry()") and should not
be backported to stable as well.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Link: https://lore.kernel.org/r/20240221112205.48389-2-dmantipov@yandex.ru
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-22 10:03:31 +01:00
Joe Damato
18e2bf0edf eventpoll: Add epoll ioctl for epoll_params
Add an ioctl for getting and setting epoll_params. User programs can use
this ioctl to get and set the busy poll usec time, packet budget, and
prefer busy poll params for a specific epoll context.

Parameters are limited:
  - busy_poll_usecs is limited to <= s32_max
  - busy_poll_budget is limited to <= NAPI_POLL_WEIGHT by unprivileged
    users (!capable(CAP_NET_ADMIN))
  - prefer_busy_poll must be 0 or 1
  - __pad must be 0

Signed-off-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-02-14 11:01:01 +00:00
Joe Damato
de57a25108 eventpoll: Add per-epoll prefer busy poll option
When using epoll-based busy poll, the prefer_busy_poll option is hardcoded
to false. Users may want to enable prefer_busy_poll to be used in
conjunction with gro_flush_timeout and defer_hard_irqs_count to keep device
IRQs masked.

Other busy poll methods allow enabling or disabling prefer busy poll via
SO_PREFER_BUSY_POLL, but epoll-based busy polling uses a hardcoded value.

Fix this edge case by adding support for a per-epoll context
prefer_busy_poll option. The default is false, as it was hardcoded before
this change.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-02-14 11:01:00 +00:00
Joe Damato
c6aa2a7778 eventpoll: Add per-epoll busy poll packet budget
When using epoll-based busy poll, the packet budget is hardcoded to
BUSY_POLL_BUDGET (8). Users may desire larger busy poll budgets, which
can potentially increase throughput when busy polling under high network
load.

Other busy poll methods allow setting the busy poll budget via
SO_BUSY_POLL_BUDGET, but epoll-based busy polling uses a hardcoded
value.

Fix this edge case by adding support for a per-epoll context busy poll
packet budget. If not specified, the default value (BUSY_POLL_BUDGET) is
used.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-02-14 11:01:00 +00:00
Joe Damato
85455c795c eventpoll: support busy poll per epoll instance
Allow busy polling on a per-epoll context basis. The per-epoll context
usec timeout value is preferred, but the pre-existing system wide sysctl
value is still supported if it specified.

busy_poll_usecs is a u32, but in a follow up patch the ioctl provided to
the user only allows setting a value from 0 to S32_MAX.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2024-02-14 11:01:00 +00:00
Huang Xiaojia
e6f7958042 epoll: Remove ep_scan_ready_list() in comments
Since commit 443f1a0422 ("lift the calls of ep_send_events_proc()
into the callers"), ep_scan_ready_list() has been removed.
But there are still several in comments. All of them should
be replaced with other caller functions.

Signed-off-by: Huang Xiaojia <huangxiaojia2@huawei.com>
Link: https://lore.kernel.org/r/20240206014353.4191262-1-huangxiaojia2@huawei.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-06 13:55:33 +01:00
Joel Granados
9d5b947535 fs: Remove the now superfluous sentinel elements from ctl_table array
This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel elements ctl_table struct. Special attention was placed in
making sure that an empty directory for fs/verity was created when
CONFIG_FS_VERITY_BUILTIN_SIGNATURES is not defined. In this case we use the
register sysctl call that expects a size.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-12-28 04:57:57 -08:00
Alexey Dobriyan
68279f9c9f treewide: mark stuff as __ro_after_init
__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-10-18 14:43:23 -07:00
Zhen Lei
05f26f86f4 epoll: simplify ep_alloc()
The get_current_user() does not fail, and moving it after kzalloc() can
simplify the code a bit.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Message-Id: <20230726032135.933-1-thunder.leizhen@huaweicloud.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-07-26 14:56:07 +02:00
Linus Torvalds
64bf6ae93e v6.5/vfs.misc
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Merge tag 'v6.5/vfs.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Miscellaneous features, cleanups, and fixes for vfs and individual fs

  Features:

   - Use mode 0600 for file created by cachefilesd so it can be run by
     unprivileged users. This aligns them with directories which are
     already created with mode 0700 by cachefilesd

   - Reorder a few members in struct file to prevent some false sharing
     scenarios

   - Indicate that an eventfd is used a semaphore in the eventfd's
     fdinfo procfs file

   - Add a missing uapi header for eventfd exposing relevant uapi
     defines

   - Let the VFS protect transitions of a superblock from read-only to
     read-write in addition to the protection it already provides for
     transitions from read-write to read-only. Protecting read-only to
     read-write transitions allows filesystems such as ext4 to perform
     internal writes, keeping writers away until the transition is
     completed

  Cleanups:

   - Arnd removed the architecture specific arch_report_meminfo()
     prototypes and added a generic one into procfs.h. Note, we got a
     report about a warning in amdpgpu codepaths that suggested this was
     bisectable to this change but we concluded it was a false positive

   - Remove unused parameters from split_fs_names()

   - Rename put_and_unmap_page() to unmap_and_put_page() to let the name
     reflect the order of the cleanup operation that has to unmap before
     the actual put

   - Unexport buffer_check_dirty_writeback() as it is not used outside
     of block device aops

   - Stop allocating aio rings from highmem

   - Protecting read-{only,write} transitions in the VFS used open-coded
     barriers in various places. Replace them with proper little helpers
     and document both the helpers and all barrier interactions involved
     when transitioning between read-{only,write} states

   - Use flexible array members in old readdir codepaths

  Fixes:

   - Use the correct type __poll_t for epoll and eventfd

   - Replace all deprecated strlcpy() invocations, whose return value
     isn't checked with an equivalent strscpy() call

   - Fix some kernel-doc warnings in fs/open.c

   - Reduce the stack usage in jffs2's xattr codepaths finally getting
     rid of this: fs/jffs2/xattr.c:887:1: error: the frame size of 1088
     bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
     royally annoying compilation warning

   - Use __FMODE_NONOTIFY instead of FMODE_NONOTIFY where an int and not
     fmode_t is required to avoid fmode_t to integer degradation
     warnings

   - Create coredumps with O_WRONLY instead of O_RDWR. There's a long
     explanation in that commit how O_RDWR is actually a bug which we
     found out with the help of Linus and git archeology

   - Fix "no previous prototype" warnings in the pipe codepaths

   - Add overflow calculations for remap_verify_area() as a signed
     addition overflow could be triggered in xfstests

   - Fix a null pointer dereference in sysv

   - Use an unsigned variable for length calculations in jfs avoiding
     compilation warnings with gcc 13

   - Fix a dangling pipe pointer in the watch queue codepath

   - The legacy mount option parser provided as a fallback by the VFS
     for filesystems not yet converted to the new mount api did prefix
     the generated mount option string with a leading ',' causing issues
     for some filesystems

   - Fix a repeated word in a comment in fs.h

   - autofs: Update the ctime when mtime is updated as mandated by
     POSIX"

* tag 'v6.5/vfs.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (27 commits)
  readdir: Replace one-element arrays with flexible-array members
  fs: Provide helpers for manipulating sb->s_readonly_remount
  fs: Protect reconfiguration of sb read-write from racing writes
  eventfd: add a uapi header for eventfd userspace APIs
  autofs: set ctime as well when mtime changes on a dir
  eventfd: show the EFD_SEMAPHORE flag in fdinfo
  fs/aio: Stop allocating aio rings from HIGHMEM
  fs: Fix comment typo
  fs: unexport buffer_check_dirty_writeback
  fs: avoid empty option when generating legacy mount string
  watch_queue: prevent dangling pipe pointer
  fs.h: Optimize file struct to prevent false sharing
  highmem: Rename put_and_unmap_page() to unmap_and_put_page()
  cachefiles: Allow the cache to be non-root
  init: remove unused names parameter in split_fs_names()
  jfs: Use unsigned variable for length calculations
  fs/sysv: Null check to prevent null-ptr-deref bug
  fs: use UB-safe check for signed addition overflow in remap_verify_area
  procfs: consolidate arch_report_meminfo declaration
  fs: pipe: reveal missing function protoypes
  ...
2023-06-26 09:50:21 -07:00
Benjamin Segall
2192bba03d epoll: ep_autoremove_wake_function should use list_del_init_careful
autoremove_wake_function uses list_del_init_careful, so should epoll's
more aggressive variant.  It only doesn't because it was copied from an
older wait.c rather than the most recent.

[bsegall@google.com: add comment]
  Link: https://lkml.kernel.org/r/xm26bki0ulsr.fsf_-_@google.com
Link: https://lkml.kernel.org/r/xm26pm6hvfer.fsf@google.com
Fixes: a16ceb1396 ("epoll: autoremove wakers even more aggressively")
Signed-off-by: Ben Segall <bsegall@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-12 11:31:52 -07:00
Min-Hua Chen
38f1755a3e fs: use correct __poll_t type
Fix the following sparse warnings by using __poll_t instead
of unsigned type.

fs/eventpoll.c:541:9: sparse: warning: restricted __poll_t degrades to integer
fs/eventfd.c:67:17: sparse: warning: restricted __poll_t degrades to integer

Signed-off-by: Min-Hua Chen <minhuadotchen@gmail.com>
Message-Id: <20230511164628.336586-1-minhuadotchen@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-05-15 09:33:09 +02:00
Linus Torvalds
33afd4b763 Mainly singleton patches all over the place. Series of note are:
- updates to scripts/gdb from Glenn Washburn
 
 - kexec cleanups from Bjorn Helgaas
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Merge tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:
 "Mainly singleton patches all over the place.

  Series of note are:

   - updates to scripts/gdb from Glenn Washburn

   - kexec cleanups from Bjorn Helgaas"

* tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (50 commits)
  mailmap: add entries for Paul Mackerras
  libgcc: add forward declarations for generic library routines
  mailmap: add entry for Oleksandr
  ocfs2: reduce ioctl stack usage
  fs/proc: add Kthread flag to /proc/$pid/status
  ia64: fix an addr to taddr in huge_pte_offset()
  checkpatch: introduce proper bindings license check
  epoll: rename global epmutex
  scripts/gdb: add GDB convenience functions $lx_dentry_name() and $lx_i_dentry()
  scripts/gdb: create linux/vfs.py for VFS related GDB helpers
  uapi/linux/const.h: prefer ISO-friendly __typeof__
  delayacct: track delays from IRQ/SOFTIRQ
  scripts/gdb: timerlist: convert int chunks to str
  scripts/gdb: print interrupts
  scripts/gdb: raise error with reduced debugging information
  scripts/gdb: add a Radix Tree Parser
  lib/rbtree: use '+' instead of '|' for setting color.
  proc/stat: remove arch_idle_time()
  checkpatch: check for misuse of the link tags
  checkpatch: allow Closes tags with links
  ...
2023-04-27 19:57:00 -07:00
Linus Torvalds
53b5e72b9d asm-generic updates for 6.4
These are various cleanups, fixing a number of uapi header files to no
 longer reference CONFIG_* symbols, and one patch that introduces the
 new CONFIG_HAS_IOPORT symbol for architectures that provide working
 inb()/outb() macros, as a preparation for adding driver dependencies
 on those in the following release.
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Merge tag 'asm-generic-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Pull asm-generic updates from Arnd Bergmann:
 "These are various cleanups, fixing a number of uapi header files to no
  longer reference CONFIG_* symbols, and one patch that introduces the
  new CONFIG_HAS_IOPORT symbol for architectures that provide working
  inb()/outb() macros, as a preparation for adding driver dependencies
  on those in the following release"

* tag 'asm-generic-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  Kconfig: introduce HAS_IOPORT option and select it as necessary
  scripts: Update the CONFIG_* ignore list in headers_install.sh
  pktcdvd: Remove CONFIG_CDROM_PKTCDVD_WCACHE from uapi header
  Move bp_type_idx to include/linux/hw_breakpoint.h
  Move ep_take_care_of_epollwakeup() to fs/eventpoll.c
  Move COMPAT_ATM_ADDPARTY to net/atm/svc.c
2023-04-25 12:22:11 -07:00
Davidlohr Bueso
d4cb626d6f epoll: rename global epmutex
As of 4f04cbaf128 ("epoll: use refcount to reduce ep_mutex contention"),
this lock is now specific to nesting cases - inserting an epoll fd onto
another epoll fd.  Rename the lock to be less generic.

Link: https://lkml.kernel.org/r/20230411234159.20421-1-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-18 16:39:35 -07:00
Paolo Abeni
58c9b016e1 epoll: use refcount to reduce ep_mutex contention
We are observing huge contention on the epmutex during an http
connection/rate test:

 83.17% 0.25%  nginx            [kernel.kallsyms]         [k] entry_SYSCALL_64_after_hwframe
[...]
           |--66.96%--__fput
                      |--60.04%--eventpoll_release_file
                                 |--58.41%--__mutex_lock.isra.6
                                           |--56.56%--osq_lock

The application is multi-threaded, creates a new epoll entry for
each incoming connection, and does not delete it before the
connection shutdown - that is, before the connection's fd close().

Many different threads compete frequently for the epmutex lock,
affecting the overall performance.

To reduce the contention this patch introduces explicit reference counting
for the eventpoll struct. Each registered event acquires a reference,
and references are released at ep_remove() time.

The eventpoll struct is released by whoever - among EP file close() and
and the monitored file close() drops its last reference.

Additionally, this introduces a new 'dying' flag to prevent races between
the EP file close() and the monitored file close().
ep_eventpoll_release() marks, under f_lock spinlock, each epitem as dying
before removing it, while EP file close() does not touch dying epitems.

The above is needed as both close operations could run concurrently and
drop the EP reference acquired via the epitem entry. Without the above
flag, the monitored file close() could reach the EP struct via the epitem
list while the epitem is still listed and then try to put it after its
disposal.

An alternative could be avoiding touching the references acquired via
the epitems at EP file close() time, but that could leave the EP struct
alive for potentially unlimited time after EP file close(), with nasty
side effects.

With all the above in place, we can drop the epmutex usage at disposal time.

Overall this produces a significant performance improvement in the
mentioned connection/rate scenario: the mutex operations disappear from
the topmost offenders in the perf report, and the measured connections/rate
grows by ~60%.

To make the change more readable this additionally renames ep_free() to
ep_clear_and_put(), and moves the actual memory cleanup in a separate
ep_free() helper.

Link: https://lkml.kernel.org/r/4a57788dcaf28f5eb4f8dfddcc3a8b172a7357bb.1679504153.git.pabeni@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Co-developed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Xiumei Mu <xmu@redhiat.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Jacob Keller <jacob.e.keller@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-08 13:45:38 -07:00
Changcheng Liu
7059a9aa4b
eventpoll: align comment with nested epoll limitation
fix comment in commit 02edc6fc4d ("epoll: comment the funky #ifdef")

Signed-off-by: Liu, Changcheng <changchengx.liu@outlook.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-13 10:33:28 +01:00
Palmer Dabbelt
063f3ed9fa Move ep_take_care_of_epollwakeup() to fs/eventpoll.c
This doesn't make any sense to expose to userspace, so it's been moved
to the one user.  This was introduced by commit 95f19f658c ("epoll:
drop EPOLLWAKEUP if PM_SLEEP is disabled").

Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
Reviewed-by: Andrew Waterman <waterman@eecs.berkeley.edu>
Reviewed-by: Albert Ou <aou@eecs.berkeley.edu>
Message-Id: <1447119071-19392-7-git-send-email-palmer@dabbelt.com>
[thuth: Rebased to fix contextual conflicts]
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2023-03-10 21:05:16 +01:00
Jens Axboe
caf1aeaffc eventpoll: add EPOLL_URING_WAKE poll wakeup flag
We can have dependencies between epoll and io_uring. Consider an epoll
context, identified by the epfd file descriptor, and an io_uring file
descriptor identified by iofd. If we add iofd to the epfd context, and
arm a multishot poll request for epfd with iofd, then the multishot
poll request will repeatedly trigger and generate events until terminated
by CQ ring overflow. This isn't a desired behavior.

Add EPOLL_URING so that io_uring can pass it in as part of the poll wakeup
key, and io_uring can check for that to detect a potential recursive
invocation.

Cc: stable@vger.kernel.org # 6.0
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21 07:45:29 -07:00
Uros Bizjak
693fc06e98 epoll: use try_cmpxchg in list_add_tail_lockless
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
list_add_tail_lockless.  x86 CMPXCHG instruction returns success in ZF
flag, so this change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).

No functional change intended.

Link: https://lkml.kernel.org/r/20220714173255.12987-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-09-11 21:55:07 -07:00
Benjamin Segall
a16ceb1396 epoll: autoremove wakers even more aggressively
If a process is killed or otherwise exits while having active network
connections and many threads waiting on epoll_wait, the threads will all
be woken immediately, but not removed from ep->wq.  Then when network
traffic scans ep->wq in wake_up, every wakeup attempt will fail, and will
not remove the entries from the list.

This means that the cost of the wakeup attempt is far higher than usual,
does not decrease, and this also competes with the dying threads trying to
actually make progress and remove themselves from the wq.

Handle this by removing visited epoll wq entries unconditionally, rather
than only when the wakeup succeeds - the structure of ep_poll means that
the only potential loss is the timed_out->eavail heuristic, which now can
race and result in a redundant ep_send_events attempt.  (But only when
incoming data and a timeout actually race, not on every timeout)

Shakeel added:

: We are seeing this issue in production with real workloads and it has
: caused hard lockups.  Particularly network heavy workloads with a lot
: of threads in epoll_wait() can easily trigger this issue if they get
: killed (oom-killed in our case).

Link: https://lkml.kernel.org/r/xm26fsjotqda.fsf@google.com
Signed-off-by: Ben Segall <bsegall@google.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Roman Penyaev <rpenyaev@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Khazhismel Kumykov <khazhy@google.com>
Cc: Heiher <r@hev.cc>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-07-17 17:31:40 -07:00
Xiaoming Ni
a8f5de894f eventpoll: simplify sysctl declaration with register_sysctl()
The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

So move the epoll_table sysctl to fs/eventpoll.c and use
register_sysctl().

Link: https://lkml.kernel.org/r/20211123202422.819032-9-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Airlie <airlied@linux.ie>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Qing Wang <wangqing@vivo.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-22 08:33:35 +02:00
Linus Torvalds
35776f1051 ARM development updates for 5.15:
- Rename "mod_init" and "mod_exit" so that initcall debug output is
   actually useful (Randy Dunlap)
 - Update maintainers entries for linux-arm-kernel to indicate it is
   moderated for non-subscribers (Randy Dunlap)
 - Move install rules to arch/arm/Makefile (Masahiro Yamada)
 - Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij)
 - Don't warn about atags_to_fdt() stack size (David Heidelberg)
 - Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann)
 - Get rid of set_fs() usage (Arnd Bergmann)
 - Remove checks for GCC prior to v4.6 (Geert Uytterhoeven)
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Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

Pull ARM development updates from Russell King:

 - Rename "mod_init" and "mod_exit" so that initcall debug output is
   actually useful (Randy Dunlap)

 - Update maintainers entries for linux-arm-kernel to indicate it is
   moderated for non-subscribers (Randy Dunlap)

 - Move install rules to arch/arm/Makefile (Masahiro Yamada)

 - Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij)

 - Don't warn about atags_to_fdt() stack size (David Heidelberg)

 - Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann)

 - Get rid of set_fs() usage (Arnd Bergmann)

 - Remove checks for GCC prior to v4.6 (Geert Uytterhoeven)

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9118/1: div64: Remove always-true __div64_const32_is_OK() duplicate
  ARM: 9117/1: asm-generic: div64: Remove always-true __div64_const32_is_OK()
  ARM: 9116/1: unified: Remove check for gcc < 4
  ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning
  ARM: 9113/1: uaccess: remove set_fs() implementation
  ARM: 9112/1: uaccess: add __{get,put}_kernel_nofault
  ARM: 9111/1: oabi-compat: rework fcntl64() emulation
  ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation
  ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation
  ARM: 9107/1: syscall: always store thread_info->abi_syscall
  ARM: 9109/1: oabi-compat: add epoll_pwait handler
  ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs()
  ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault
  ARM: 9105/1: atags_to_fdt: don't warn about stack size
  ARM: 9103/1: Drop ARCH_NR_GPIOS definition
  ARM: 9102/1: move theinstall rules to arch/arm/Makefile
  ARM: 9100/1: MAINTAINERS: mark all linux-arm-kernel@infradead list as moderated
  ARM: 9099/1: crypto: rename 'mod_init' & 'mod_exit' functions to be module-specific
2021-09-09 13:25:49 -07:00
Nicholas Piggin
1e1c15839d fs/epoll: use a per-cpu counter for user's watches count
This counter tracks the number of watches a user has, to compare against
the 'max_user_watches' limit. This causes a scalability bottleneck on
SPECjbb2015 on large systems as there is only one user. Changing to a
per-cpu counter increases throughput of the benchmark by about 30% on a
16-socket, > 1000 thread system.

[rdunlap@infradead.org: fix build errors in kernel/user.c when CONFIG_EPOLL=n]
[npiggin@gmail.com: move ifdefs into wrapper functions, slightly improve panic message]
  Link: https://lkml.kernel.org/r/1628051945.fens3r99ox.astroid@bobo.none
[akpm@linux-foundation.org: tweak user_epoll_alloc(), per Guenter]
  Link: https://lkml.kernel.org/r/20210804191421.GA1900577@roeck-us.net

Link: https://lkml.kernel.org/r/20210802032013.2751916-1-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reported-by: Anton Blanchard <anton@ozlabs.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-08 11:50:27 -07:00
Arnd Bergmann
249dbe74d3 ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation
The epoll_wait() system call wrapper is one of the remaining users of
the set_fs() infrasturcture for Arm. Changing it to not require set_fs()
is rather complex unfortunately.

The approach I'm taking here is to allow architectures to override
the code that copies the output to user space, and let the oabi-compat
implementation check whether it is getting called from an EABI or OABI
system call based on the thread_info->syscall value.

The in_oabi_syscall() check here mirrors the in_compat_syscall() and
in_x32_syscall() helpers for 32-bit compat implementations on other
architectures.

Overall, the amount of code goes down, at least with the newly added
sys_oabi_epoll_pwait() helper getting removed again. The downside
is added complexity in the source code for the native implementation.
There should be no difference in runtime performance except for Arm
kernels with CONFIG_OABI_COMPAT enabled that now have to go through
an external function call to check which of the two variants to use.

Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
2021-08-20 11:39:26 +01:00
Davidlohr Bueso
7fab29e356 fs/epoll: restore waking from ep_done_scan()
Commit 339ddb53d3 ("fs/epoll: remove unnecessary wakeups of nested
epoll") changed the userspace visible behavior of exclusive waiters
blocked on a common epoll descriptor upon a single event becoming ready.

Previously, all tasks doing epoll_wait would awake, and now only one is
awoken, potentially causing missed wakeups on applications that rely on
this behavior, such as Apache Qpid.

While the aforementioned commit aims at having only a wakeup single path
in ep_poll_callback (with the exceptions of epoll_ctl cases), we need to
restore the wakeup in what was the old ep_scan_ready_list() such that
the next thread can be awoken, in a cascading style, after the waker's
corresponding ep_send_events().

Link: https://lkml.kernel.org/r/20210405231025.33829-3-dave@stgolabs.net
Fixes: 339ddb53d3 ("fs/epoll: remove unnecessary wakeups of nested epoll")
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Roman Penyaev <rpenyaev@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-06 19:24:13 -07:00
Randy Dunlap
a6c67fee9c fs: eventpoll: fix comments & kernel-doc notation
Use the documented kernel-doc format for function Return: descriptions.
Begin constant values in kernel-doc comments with '%'.

Remove kernel-doc "/**" from 2 functions that are not documented with
kernel-doc notation.

Fix typos, punctuation, & grammar.

Also fix a few kernel-doc warnings:

../fs/eventpoll.c:1883: warning: Function parameter or member 'ep' not described in 'ep_loop_check_proc'
../fs/eventpoll.c:1883: warning: Excess function parameter 'priv' description in 'ep_loop_check_proc'
../fs/eventpoll.c:1932: warning: Function parameter or member 'ep' not described in 'ep_loop_check'
../fs/eventpoll.c:1932: warning: Excess function parameter 'from' description in 'ep_loop_check'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-03-06 17:36:53 -07:00
Chris Wilson
bfe3911a91 kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE
Userspace has discovered the functionality offered by SYS_kcmp and has
started to depend upon it. In particular, Mesa uses SYS_kcmp for
os_same_file_description() in order to identify when two fd (e.g. device
or dmabuf) point to the same struct file. Since they depend on it for
core functionality, lift SYS_kcmp out of the non-default
CONFIG_CHECKPOINT_RESTORE into the selectable syscall category.

Rasmus Villemoes also pointed out that systemd uses SYS_kcmp to
deduplicate the per-service file descriptor store.

Note that some distributions such as Ubuntu are already enabling
CHECKPOINT_RESTORE in their configs and so, by extension, SYS_kcmp.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/3046
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> # DRM depends on kcmp
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> # systemd uses kcmp
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210205220012.1983-1-chris@chris-wilson.co.uk
2021-02-16 09:59:41 +01:00
Willem de Bruijn
58169a52eb epoll: add syscall epoll_pwait2
Add syscall epoll_pwait2, an epoll_wait variant with nsec resolution that
replaces int timeout with struct timespec.  It is equivalent otherwise.

    int epoll_pwait2(int fd, struct epoll_event *events,
                     int maxevents,
                     const struct timespec *timeout,
                     const sigset_t *sigset);

The underlying hrtimer is already programmed with nsec resolution.
pselect and ppoll also set nsec resolution timeout with timespec.

The sigset_t in epoll_pwait has a compat variant. epoll_pwait2 needs
the same.

For timespec, only support this new interface on 2038 aware platforms
that define __kernel_timespec_t. So no CONFIG_COMPAT_32BIT_TIME.

Link: https://lkml.kernel.org/r/20201121144401.3727659-3-willemdebruijn.kernel@gmail.com
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:38 -08:00
Willem de Bruijn
7cdf7c20e9 epoll: convert internal api to timespec64
Patch series "add epoll_pwait2 syscall", v4.

Enable nanosecond timeouts for epoll.

Analogous to pselect and ppoll, introduce an epoll_wait syscall
variant that takes a struct timespec instead of int timeout.

This patch (of 4):

Make epoll more consistent with select/poll: pass along the timeout as
timespec64 pointer.

In anticipation of additional changes affecting all three polling
mechanisms:

- add epoll_pwait2 syscall with timespec semantics,
  and share poll_select_set_timeout implementation.
- compute slack before conversion to absolute time,
  to save one ktime_get_ts64 call.

Link: https://lkml.kernel.org/r/20201121144401.3727659-1-willemdebruijn.kernel@gmail.com
Link: https://lkml.kernel.org/r/20201121144401.3727659-2-willemdebruijn.kernel@gmail.com
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:38 -08:00
Soheil Hassas Yeganeh
e59d3c64cb epoll: eliminate unnecessary lock for zero timeout
We call ep_events_available() under lock when timeout is 0, and then call
it without locks in the loop for the other cases.

Instead, call ep_events_available() without lock for all cases.  For
non-zero timeouts, we will recheck after adding the thread to the wait
queue.  For zero timeout cases, by definition, user is opportunistically
polling and will have to call epoll_wait again in the future.

Note that this lock was kept in c5a282e963 because the whole loop was
historically under lock.

This patch results in a 1% CPU/RPC reduction in RPC benchmarks.

Link: https://lkml.kernel.org/r/20201106231635.3528496-9-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:38 -08:00
Soheil Hassas Yeganeh
00b27634bc epoll: replace gotos with a proper loop
The existing loop is pointless, and the labels make it really hard to
follow the structure.

Replace that control structure with a simple loop that returns when there
are new events, there is a signal, or the thread has timed out.

Link: https://lkml.kernel.org/r/20201106231635.3528496-8-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:38 -08:00
Soheil Hassas Yeganeh
e8c85328b1 epoll: pull all code between fetch_events and send_event into the loop
This is a no-op change which simplifies the follow up patches.

Link: https://lkml.kernel.org/r/20201106231635.3528496-7-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:38 -08:00
Soheil Hassas Yeganeh
1493c47fb1 epoll: simplify and optimize busy loop logic
ep_events_available() is called multiple times around the busy loop logic,
even though the logic is generally not used.  ep_reset_busy_poll_napi_id()
is similarly always called, even when busy loop is not used.

Eliminate ep_reset_busy_poll_napi_id() and inline it inside
ep_busy_loop().  Make ep_busy_loop() return whether there are any events
available after the busy loop.  This will eliminate unnecessary loads and
branches, and simplifies the loop.

Link: https://lkml.kernel.org/r/20201106231635.3528496-6-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:37 -08:00
Soheil Hassas Yeganeh
e411596d48 epoll: move eavail next to the list_empty_careful check
This is a no-op change and simply to make the code more coherent.

Link: https://lkml.kernel.org/r/20201106231635.3528496-5-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:37 -08:00
Soheil Hassas Yeganeh
cccd29bf08 epoll: pull fatal signal checks into ep_send_events()
To simplify the code, pull in checking the fatal signals into
ep_send_events().  ep_send_events() is called only from ep_poll().

Note that, previously, we were always checking fatal events, but it is
checked only if eavail is true.  This should be fine because the goal of
that check is to quickly return from epoll_wait() when there is a pending
fatal signal.

Link: https://lkml.kernel.org/r/20201106231635.3528496-4-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:37 -08:00
Soheil Hassas Yeganeh
2efdaf7660 epoll: simplify signal handling
Check signals before locking ep->lock, and immediately return -EINTR if
there is any signal pending.

This saves a few loads, stores, and branches from the hot path and
simplifies the loop structure for follow up patches.

Link: https://lkml.kernel.org/r/20201106231635.3528496-3-soheil.kdev@gmail.com
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Khazhismel Kumykov <khazhy@google.com>
Cc: Guantao Liu <guantaol@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-19 11:18:37 -08:00