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ipc: optimize semget/shmget/msgget for lots of keys
ipc_findkey() used to scan all objects to look for the wanted key. This
is slow when using a high number of keys. This change adds an rhashtable
of kern_ipc_perm objects in ipc_ids, so that one lookup cease to be O(n).
This change gives a 865% improvement of benchmark reaim.jobs_per_min on a
56 threads Intel(R) Xeon(R) CPU E5-2695 v3 @ 2.30GHz with 256G memory [1]
Other (more micro) benchmark results, by the author: On an i5 laptop, the
following loop executed right after a reboot took, without and with this
change:
for (int i = 0, k=0x424242; i < KEYS; ++i)
semget(k++, 1, IPC_CREAT | 0600);
total total max single max single
KEYS without with call without call with
1 3.5 4.9 µs 3.5 4.9
10 7.6 8.6 µs 3.7 4.7
32 16.2 15.9 µs 4.3 5.3
100 72.9 41.8 µs 3.7 4.7
1000 5,630.0 502.0 µs * *
10000 1,340,000.0 7,240.0 µs * *
31900 17,600,000.0 22,200.0 µs * *
*: unreliable measure: high variance
The duration for a lookup-only usage was obtained by the same loop once
the keys are present:
total total max single max single
KEYS without with call without call with
1 2.1 2.5 µs 2.1 2.5
10 4.5 4.8 µs 2.2 2.3
32 13.0 10.8 µs 2.3 2.8
100 82.9 25.1 µs * 2.3
1000 5,780.0 217.0 µs * *
10000 1,470,000.0 2,520.0 µs * *
31900 17,400,000.0 7,810.0 µs * *
Finally, executing each semget() in a new process gave, when still
summing only the durations of these syscalls:
creation:
total total
KEYS without with
1 3.7 5.0 µs
10 32.9 36.7 µs
32 125.0 109.0 µs
100 523.0 353.0 µs
1000 20,300.0 3,280.0 µs
10000 2,470,000.0 46,700.0 µs
31900 27,800,000.0 219,000.0 µs
lookup-only:
total total
KEYS without with
1 2.5 2.7 µs
10 25.4 24.4 µs
32 106.0 72.6 µs
100 591.0 352.0 µs
1000 22,400.0 2,250.0 µs
10000 2,510,000.0 25,700.0 µs
31900 28,200,000.0 115,000.0 µs
[1] http://lkml.kernel.org/r/20170814060507.GE23258@yexl-desktop
Link: http://lkml.kernel.org/r/20170815194954.ck32ta2z35yuzpwp@debix
Signed-off-by: Guillaume Knispel <guillaume.knispel@supersonicimagine.com>
Reviewed-by: Marc Pardo <marc.pardo@supersonicimagine.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: Guillaume Knispel <guillaume.knispel@supersonicimagine.com>
Cc: Marc Pardo <marc.pardo@supersonicimagine.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Guillaume Knispel
Linus Torvalds
parent
e4243b8062
commit
0cfb6aee70
@ -3,6 +3,7 @@
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#include <linux/spinlock.h>
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#include <linux/uidgid.h>
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#include <linux/rhashtable.h>
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#include <uapi/linux/ipc.h>
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#include <linux/refcount.h>
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@ -22,6 +23,8 @@ struct kern_ipc_perm {
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unsigned long seq;
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void *security;
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struct rhash_head khtnode;
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struct rcu_head rcu;
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refcount_t refcount;
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} ____cacheline_aligned_in_smp __randomize_layout;
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@ -8,15 +8,18 @@
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#include <linux/nsproxy.h>
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#include <linux/ns_common.h>
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#include <linux/refcount.h>
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#include <linux/rhashtable.h>
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struct user_namespace;
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struct ipc_ids {
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int in_use;
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unsigned short seq;
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bool tables_initialized;
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struct rw_semaphore rwsem;
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struct idr ipcs_idr;
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int next_id;
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struct rhashtable key_ht;
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};
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struct ipc_namespace {
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10
ipc/msg.c
10
ipc/msg.c
@ -1011,7 +1011,7 @@ SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
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}
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void msg_init_ns(struct ipc_namespace *ns)
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int msg_init_ns(struct ipc_namespace *ns)
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{
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ns->msg_ctlmax = MSGMAX;
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ns->msg_ctlmnb = MSGMNB;
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@ -1019,7 +1019,7 @@ void msg_init_ns(struct ipc_namespace *ns)
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atomic_set(&ns->msg_bytes, 0);
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atomic_set(&ns->msg_hdrs, 0);
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ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
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return ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
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}
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#ifdef CONFIG_IPC_NS
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@ -1027,6 +1027,7 @@ void msg_exit_ns(struct ipc_namespace *ns)
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{
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free_ipcs(ns, &msg_ids(ns), freeque);
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idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
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rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
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}
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#endif
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@ -1058,11 +1059,12 @@ static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
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}
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#endif
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void __init msg_init(void)
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int __init msg_init(void)
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{
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msg_init_ns(&init_ipc_ns);
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const int err = msg_init_ns(&init_ipc_ns);
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ipc_init_proc_interface("sysvipc/msg",
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" key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
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IPC_MSG_IDS, sysvipc_msg_proc_show);
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return err;
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}
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@ -54,16 +54,28 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
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ns->user_ns = get_user_ns(user_ns);
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ns->ucounts = ucounts;
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err = mq_init_ns(ns);
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err = sem_init_ns(ns);
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if (err)
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goto fail_put;
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err = msg_init_ns(ns);
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if (err)
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goto fail_destroy_sem;
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err = shm_init_ns(ns);
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if (err)
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goto fail_destroy_msg;
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sem_init_ns(ns);
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msg_init_ns(ns);
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shm_init_ns(ns);
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err = mq_init_ns(ns);
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if (err)
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goto fail_destroy_shm;
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return ns;
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fail_destroy_shm:
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shm_exit_ns(ns);
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fail_destroy_msg:
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msg_exit_ns(ns);
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fail_destroy_sem:
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sem_exit_ns(ns);
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fail_put:
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put_user_ns(ns->user_ns);
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ns_free_inum(&ns->ns);
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11
ipc/sem.c
11
ipc/sem.c
@ -183,14 +183,14 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
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#define sc_semopm sem_ctls[2]
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#define sc_semmni sem_ctls[3]
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void sem_init_ns(struct ipc_namespace *ns)
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int sem_init_ns(struct ipc_namespace *ns)
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{
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ns->sc_semmsl = SEMMSL;
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ns->sc_semmns = SEMMNS;
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ns->sc_semopm = SEMOPM;
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ns->sc_semmni = SEMMNI;
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ns->used_sems = 0;
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ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
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return ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
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}
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#ifdef CONFIG_IPC_NS
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@ -198,15 +198,18 @@ void sem_exit_ns(struct ipc_namespace *ns)
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{
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free_ipcs(ns, &sem_ids(ns), freeary);
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idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr);
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rhashtable_destroy(&ns->ids[IPC_SEM_IDS].key_ht);
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}
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#endif
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void __init sem_init(void)
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int __init sem_init(void)
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{
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sem_init_ns(&init_ipc_ns);
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const int err = sem_init_ns(&init_ipc_ns);
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ipc_init_proc_interface("sysvipc/sem",
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" key semid perms nsems uid gid cuid cgid otime ctime\n",
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IPC_SEM_IDS, sysvipc_sem_proc_show);
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return err;
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}
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/**
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12
ipc/shm.c
12
ipc/shm.c
@ -72,14 +72,14 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
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static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
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#endif
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void shm_init_ns(struct ipc_namespace *ns)
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int shm_init_ns(struct ipc_namespace *ns)
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{
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ns->shm_ctlmax = SHMMAX;
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ns->shm_ctlall = SHMALL;
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ns->shm_ctlmni = SHMMNI;
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ns->shm_rmid_forced = 0;
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ns->shm_tot = 0;
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ipc_init_ids(&shm_ids(ns));
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return ipc_init_ids(&shm_ids(ns));
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}
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/*
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@ -95,7 +95,7 @@ static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
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if (shp->shm_nattch) {
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shp->shm_perm.mode |= SHM_DEST;
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/* Do not find it any more */
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shp->shm_perm.key = IPC_PRIVATE;
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ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
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shm_unlock(shp);
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} else
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shm_destroy(ns, shp);
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@ -106,13 +106,15 @@ void shm_exit_ns(struct ipc_namespace *ns)
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{
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free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
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idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
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rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
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}
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#endif
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static int __init ipc_ns_init(void)
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{
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shm_init_ns(&init_ipc_ns);
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return 0;
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const int err = shm_init_ns(&init_ipc_ns);
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WARN(err, "ipc: sysv shm_init_ns failed: %d\n", err);
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return err;
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}
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pure_initcall(ipc_ns_init);
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100
ipc/util.c
100
ipc/util.c
@ -83,27 +83,46 @@ struct ipc_proc_iface {
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*/
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static int __init ipc_init(void)
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{
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sem_init();
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msg_init();
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int err_sem, err_msg;
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err_sem = sem_init();
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WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem);
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err_msg = msg_init();
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WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg);
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shm_init();
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return 0;
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return err_msg ? err_msg : err_sem;
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}
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device_initcall(ipc_init);
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static const struct rhashtable_params ipc_kht_params = {
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.head_offset = offsetof(struct kern_ipc_perm, khtnode),
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.key_offset = offsetof(struct kern_ipc_perm, key),
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.key_len = FIELD_SIZEOF(struct kern_ipc_perm, key),
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.locks_mul = 1,
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.automatic_shrinking = true,
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};
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/**
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* ipc_init_ids - initialise ipc identifiers
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* @ids: ipc identifier set
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*
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* Set up the sequence range to use for the ipc identifier range (limited
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* below IPCMNI) then initialise the ids idr.
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* below IPCMNI) then initialise the keys hashtable and ids idr.
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*/
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void ipc_init_ids(struct ipc_ids *ids)
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int ipc_init_ids(struct ipc_ids *ids)
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{
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int err;
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ids->in_use = 0;
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ids->seq = 0;
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ids->next_id = -1;
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init_rwsem(&ids->rwsem);
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err = rhashtable_init(&ids->key_ht, &ipc_kht_params);
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if (err)
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return err;
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idr_init(&ids->ipcs_idr);
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ids->tables_initialized = true;
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return 0;
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}
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#ifdef CONFIG_PROC_FS
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@ -147,28 +166,20 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
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* Returns the locked pointer to the ipc structure if found or NULL
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* otherwise. If key is found ipc points to the owning ipc structure
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*
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* Called with ipc_ids.rwsem held.
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* Called with writer ipc_ids.rwsem held.
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*/
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static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
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{
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struct kern_ipc_perm *ipc;
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int next_id;
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int total;
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struct kern_ipc_perm *ipcp = NULL;
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for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
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ipc = idr_find(&ids->ipcs_idr, next_id);
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if (ipc == NULL)
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continue;
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if (ipc->key != key) {
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total++;
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continue;
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}
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if (likely(ids->tables_initialized))
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ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
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ipc_kht_params);
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if (ipcp) {
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rcu_read_lock();
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ipc_lock_object(ipc);
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return ipc;
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ipc_lock_object(ipcp);
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return ipcp;
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}
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return NULL;
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@ -221,13 +232,13 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
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{
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kuid_t euid;
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kgid_t egid;
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int id;
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int id, err;
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int next_id = ids->next_id;
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if (size > IPCMNI)
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size = IPCMNI;
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if (ids->in_use >= size)
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if (!ids->tables_initialized || ids->in_use >= size)
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return -ENOSPC;
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idr_preload(GFP_KERNEL);
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@ -246,6 +257,15 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
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(next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
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GFP_NOWAIT);
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idr_preload_end();
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if (id >= 0 && new->key != IPC_PRIVATE) {
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err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
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ipc_kht_params);
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if (err < 0) {
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idr_remove(&ids->ipcs_idr, id);
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id = err;
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}
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}
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if (id < 0) {
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spin_unlock(&new->lock);
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rcu_read_unlock();
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@ -377,6 +397,20 @@ static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
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return err;
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}
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/**
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* ipc_kht_remove - remove an ipc from the key hashtable
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* @ids: ipc identifier set
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* @ipcp: ipc perm structure containing the key to remove
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*
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* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
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* before this function is called, and remain locked on the exit.
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*/
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static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
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{
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if (ipcp->key != IPC_PRIVATE)
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rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
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ipc_kht_params);
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}
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/**
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* ipc_rmid - remove an ipc identifier
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@ -391,10 +425,25 @@ void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
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int lid = ipcid_to_idx(ipcp->id);
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idr_remove(&ids->ipcs_idr, lid);
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ipc_kht_remove(ids, ipcp);
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ids->in_use--;
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ipcp->deleted = true;
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}
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/**
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* ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
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* @ids: ipc identifier set
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* @ipcp: ipc perm structure containing the key to modify
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*
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* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
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* before this function is called, and remain locked on the exit.
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*/
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void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
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{
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ipc_kht_remove(ids, ipcp);
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ipcp->key = IPC_PRIVATE;
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}
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int ipc_rcu_getref(struct kern_ipc_perm *ptr)
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{
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return refcount_inc_not_zero(&ptr->refcount);
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@ -485,7 +534,7 @@ void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
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}
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/**
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* ipc_obtain_object
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* ipc_obtain_object_idr
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* @ids: ipc identifier set
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* @id: ipc id to look for
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*
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@ -499,6 +548,9 @@ struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
|
||||
struct kern_ipc_perm *out;
|
||||
int lid = ipcid_to_idx(id);
|
||||
|
||||
if (unlikely(!ids->tables_initialized))
|
||||
return ERR_PTR(-EINVAL);
|
||||
|
||||
out = idr_find(&ids->ipcs_idr, lid);
|
||||
if (!out)
|
||||
return ERR_PTR(-EINVAL);
|
||||
|
||||
21
ipc/util.h
21
ipc/util.h
@ -15,8 +15,8 @@
|
||||
|
||||
#define SEQ_MULTIPLIER (IPCMNI)
|
||||
|
||||
void sem_init(void);
|
||||
void msg_init(void);
|
||||
int sem_init(void);
|
||||
int msg_init(void);
|
||||
void shm_init(void);
|
||||
|
||||
struct ipc_namespace;
|
||||
@ -30,17 +30,17 @@ static inline void mq_put_mnt(struct ipc_namespace *ns) { }
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_SYSVIPC
|
||||
void sem_init_ns(struct ipc_namespace *ns);
|
||||
void msg_init_ns(struct ipc_namespace *ns);
|
||||
void shm_init_ns(struct ipc_namespace *ns);
|
||||
int sem_init_ns(struct ipc_namespace *ns);
|
||||
int msg_init_ns(struct ipc_namespace *ns);
|
||||
int shm_init_ns(struct ipc_namespace *ns);
|
||||
|
||||
void sem_exit_ns(struct ipc_namespace *ns);
|
||||
void msg_exit_ns(struct ipc_namespace *ns);
|
||||
void shm_exit_ns(struct ipc_namespace *ns);
|
||||
#else
|
||||
static inline void sem_init_ns(struct ipc_namespace *ns) { }
|
||||
static inline void msg_init_ns(struct ipc_namespace *ns) { }
|
||||
static inline void shm_init_ns(struct ipc_namespace *ns) { }
|
||||
static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; }
|
||||
static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
|
||||
static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; }
|
||||
|
||||
static inline void sem_exit_ns(struct ipc_namespace *ns) { }
|
||||
static inline void msg_exit_ns(struct ipc_namespace *ns) { }
|
||||
@ -79,7 +79,7 @@ struct ipc_ops {
|
||||
struct seq_file;
|
||||
struct ipc_ids;
|
||||
|
||||
void ipc_init_ids(struct ipc_ids *);
|
||||
int ipc_init_ids(struct ipc_ids *);
|
||||
#ifdef CONFIG_PROC_FS
|
||||
void __init ipc_init_proc_interface(const char *path, const char *header,
|
||||
int ids, int (*show)(struct seq_file *, void *));
|
||||
@ -104,6 +104,9 @@ int ipc_get_maxid(struct ipc_ids *);
|
||||
/* must be called with both locks acquired. */
|
||||
void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
|
||||
|
||||
/* must be called with both locks acquired. */
|
||||
void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
|
||||
|
||||
/* must be called with ipcp locked */
|
||||
int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user