When the following filter is used it causes a warning to trigger:
# cd /sys/kernel/debug/tracing
# echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
-bash: echo: write error: Invalid argument
# cat events/ext4/ext4_truncate_exit/filter
((dev==1)blocks==2)
^
parse_error: No error
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1223 at kernel/trace/trace_events_filter.c:1640 replace_preds+0x3c5/0x990()
Modules linked in: bnep lockd grace bluetooth ...
CPU: 3 PID: 1223 Comm: bash Tainted: G W 4.1.0-rc3-test+ #450
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
0000000000000668 ffff8800c106bc98 ffffffff816ed4f9 ffff88011ead0cf0
0000000000000000 ffff8800c106bcd8 ffffffff8107fb07 ffffffff8136b46c
ffff8800c7d81d48 ffff8800d4c2bc00 ffff8800d4d4f920 00000000ffffffea
Call Trace:
[<ffffffff816ed4f9>] dump_stack+0x4c/0x6e
[<ffffffff8107fb07>] warn_slowpath_common+0x97/0xe0
[<ffffffff8136b46c>] ? _kstrtoull+0x2c/0x80
[<ffffffff8107fb6a>] warn_slowpath_null+0x1a/0x20
[<ffffffff81159065>] replace_preds+0x3c5/0x990
[<ffffffff811596b2>] create_filter+0x82/0xb0
[<ffffffff81159944>] apply_event_filter+0xd4/0x180
[<ffffffff81152bbf>] event_filter_write+0x8f/0x120
[<ffffffff811db2a8>] __vfs_write+0x28/0xe0
[<ffffffff811dda43>] ? __sb_start_write+0x53/0xf0
[<ffffffff812e51e0>] ? security_file_permission+0x30/0xc0
[<ffffffff811dc408>] vfs_write+0xb8/0x1b0
[<ffffffff811dc72f>] SyS_write+0x4f/0xb0
[<ffffffff816f5217>] system_call_fastpath+0x12/0x6a
---[ end trace e11028bd95818dcd ]---
Worse yet, reading the error message (the filter again) it says that
there was no error, when there clearly was. The issue is that the
code that checks the input does not check for balanced ops. That is,
having an op between a closed parenthesis and the next token.
This would only cause a warning, and fail out before doing any real
harm, but it should still not caues a warning, and the error reported
should work:
# cd /sys/kernel/debug/tracing
# echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
-bash: echo: write error: Invalid argument
# cat events/ext4/ext4_truncate_exit/filter
((dev==1)blocks==2)
^
parse_error: Meaningless filter expression
And give no kernel warning.
Link: http://lkml.kernel.org/r/20150615175025.7e809215@gandalf.local.home
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: stable@vger.kernel.org # 2.6.31+
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The functions irq_move_irq() and irq_move_masked_irq() expect that the
caller passes the top-level irq_data to them when hierarchical
irqdomains are enabled. But that's not true when called from
apic_ack_edge(), which results in a null pointer dereference by
idata->chip->irq_mask(idata).
Instead of fixing callers to passing top-level irq_data, we rather
change irq_move_irq()/irq_move_masked_irq() to accept any irq_data.
Fixes: 52f518a3a7 'x86/MSI: Use hierarchical irqdomains to manage MSI interrupts'
Reported-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/1433145945-789-3-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
For irq associated with hierarchy irqdomains, there will be multiple
irq_datas for one irq_desc. So enhance irq_data_to_desc() to support
hierarchy irqdomain. Also export irq_data_to_desc() as an inline
function for later reuse.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/1433145945-789-2-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull lockdep fix from Ingo Molnar:
"A lockdep/modules unload race fix that can oops"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
lockdep: Fix a race between /proc/lock_stat and module unload
Introduce helper function irq_data_get_node() and variants thereof to
hide struct irq_data implementation details.
Convert the core code to use them.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: http://lkml.kernel.org/r/1433145945-789-5-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
With the introduction of hierarchy irqdomain, struct irq_data becomes
per-chip instead of per-irq and there may be multiple irq_datas
associated with the same irq. Some per-irq data stored in struct
irq_data now may get duplicated into multiple irq_datas, and causes
inconsistent view.
So introduce struct irq_common_data to host per-irq common data and to
achieve consistent view among irq_chips.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/1433145945-789-4-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The functions irq_move_irq() and irq_move_masked_irq() expect that the
caller passes the top-level irq_data to them when hierarchical
irqdomains are enabled. But that's not true when called from
apic_ack_edge(), which results in a null pointer dereference by
idata->chip->irq_mask(idata).
Instead of fixing callers to passing top-level irq_data, we rather
change irq_move_irq()/irq_move_masked_irq() to accept any irq_data.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/1433145945-789-3-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
For irq associated with hierarchy irqdomains, there will be multiple
irq_datas for one irq_desc. So enhance irq_data_to_desc() to support
hierarchy irqdomain. Also export irq_data_to_desc() as an inline
function for later reuse.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/1433145945-789-2-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since the leapsecond is applied at tick-time, this means there is a
small window of time at the start of a leap-second where we cross into
the next second before applying the leap.
This patch modified adjtimex so that the leap-second is applied on the
second edge. Providing more correct leapsecond behavior.
This does make it so that adjtimex()'s returned time values can be
inconsistent with time values read from gettimeofday() or
clock_gettime(CLOCK_REALTIME,...) for a brief period of one tick at
the leapsecond. However, those other interfaces do not provide the
TIME_OOP time_state return that adjtimex() provides, which allows the
leapsecond to be properly represented. They instead only see a time
discontinuity, and cannot tell the first 23:59:59 from the repeated
23:59:59 leap second.
This seems like a reasonable tradeoff given clock_gettime() /
gettimeofday() cannot properly represent a leapsecond, and users
likely care more about performance, while folks who are using
adjtimex() more likely care about leap-second correctness.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434063297-28657-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently, leapsecond adjustments are done at tick time. As a result,
the leapsecond was applied at the first timer tick *after* the
leapsecond (~1-10ms late depending on HZ), rather then exactly on the
second edge.
This was in part historical from back when we were always tick based,
but correcting this since has been avoided since it adds extra
conditional checks in the gettime fastpath, which has performance
overhead.
However, it was recently pointed out that ABS_TIME CLOCK_REALTIME
timers set for right after the leapsecond could fire a second early,
since some timers may be expired before we trigger the timekeeping
timer, which then applies the leapsecond.
This isn't quite as bad as it sounds, since behaviorally it is similar
to what is possible w/ ntpd made leapsecond adjustments done w/o using
the kernel discipline. Where due to latencies, timers may fire just
prior to the settimeofday call. (Also, one should note that all
applications using CLOCK_REALTIME timers should always be careful,
since they are prone to quirks from settimeofday() disturbances.)
However, the purpose of having the kernel do the leap adjustment is to
avoid such latencies, so I think this is worth fixing.
So in order to properly keep those timers from firing a second early,
this patch modifies the ntp and timekeeping logic so that we keep
enough state so that the update_base_offsets_now accessor, which
provides the hrtimer core the current time, can check and apply the
leapsecond adjustment on the second edge. This prevents the hrtimer
core from expiring timers too early.
This patch does not modify any other time read path, so no additional
overhead is incurred. However, this also means that the leap-second
continues to be applied at tick time for all other read-paths.
Apologies to Richard Cochran, who pushed for similar changes years
ago, which I resisted due to the concerns about the performance
overhead.
While I suspect this isn't extremely critical, folks who care about
strict leap-second correctness will likely want to watch
this. Potentially a -stable candidate eventually.
Originally-suggested-by: Richard Cochran <richardcochran@gmail.com>
Reported-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Reported-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434063297-28657-4-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Currently the leapsecond logic uses what looks like magic values.
Improve this by defining SECS_PER_DAY and using that macro
to make the logic more clear.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434063297-28657-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
It was reported that 868a3e915f (hrtimer: Make offset
update smarter) was causing timer problems after suspend/resume.
The problem with that change is the modification to
clock_was_set_seq in timekeeping_update is done prior to
mirroring the time state to the shadow-timekeeper. Thus the
next time we do update_wall_time() the updated sequence is
overwritten by whats in the shadow copy.
This patch moves the shadow-timekeeper mirroring to the end
of the function, after all updates have been made, so all data
is kept in sync.
(This patch also affects the update_fast_timekeeper calls which
were also problematically done prior to the mirroring).
Reported-and-tested-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1434063297-28657-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
ring buffer benchmark, where the produce_fifo was being ignored
and the producer thread's priority was being set with the consumer_fifo
parameter.
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Merge tag 'trace-rb-bm-fix-4.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull ring buffer benchmark buglet fix from Steven Rostedt:
"Wang Long fixed a minor bug in the module parameter for the ring
buffer benchmark, where the produce_fifo was being ignored and the
producer thread's priority was being set with the consumer_fifo
parameter"
* tag 'trace-rb-bm-fix-4.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ring-buffer-benchmark: Fix the wrong sched_priority of producer
Jovi Zhangwei reported the following problem
Below kernel vm bug can be triggered by tcpdump which mmaped a lot of pages
with GFP_COMP flag.
[Mon May 25 05:29:33 2015] page:ffffea0015414000 count:66 mapcount:1 mapping: (null) index:0x0
[Mon May 25 05:29:33 2015] flags: 0x20047580004000(head)
[Mon May 25 05:29:33 2015] page dumped because: VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page))
[Mon May 25 05:29:33 2015] ------------[ cut here ]------------
[Mon May 25 05:29:33 2015] kernel BUG at mm/migrate.c:1661!
[Mon May 25 05:29:33 2015] invalid opcode: 0000 [#1] SMP
In this case it was triggered by running tcpdump but it's not necessary
reproducible on all systems.
sudo tcpdump -i bond0.100 'tcp port 4242' -c 100000000000 -w 4242.pcap
Compound pages cannot be migrated and it was not expected that such pages
be marked for NUMA balancing. This did not take into account that drivers
such as net/packet/af_packet.c may insert compound pages into userspace
with vm_insert_page. This patch tells the NUMA balancing protection
scanner to skip all VM_MIXEDMAP mappings which avoids the possibility that
compound pages are marked for migration.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Jovi Zhangwei <jovi@cloudflare.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
clocksource messages aren't prefixed in dmesg so it's a bit unclear
what subsystem emits the messages.
Use pr_fmt and pr_<level> to auto-prefix the messages appropriately.
Miscellanea:
o Remove "Warning" from KERN_WARNING level messages
o Align "timekeeping watchdog: " messages
o Coalesce formats
o Align multiline arguments
Signed-off-by: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1432579795.2846.75.camel@perches.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Refactor the usecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability. This is analogous to the msecs_to_jiffies()
cleanup in commit ca42aaf0c8 ("time: Refactor msecs_to_jiffies")
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1432832996-12129-1-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The MPX code can only work on the current task. You can not,
for instance, enable MPX management in another process or
thread. You can also not handle a fault for another process or
thread.
Despite this, we pass a task_struct around prolifically. This
patch removes all of the task struct passing for code paths
where the code can not deal with another task (which turns out
to be all of them).
This has no functional changes. It's just a cleanup.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bp@alien8.de
Link: http://lkml.kernel.org/r/20150607183702.6A81DA2C@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After enlarging the PEBS interrupt threshold, there may be some mixed up
PEBS samples which are discarded by the kernel.
This patch makes the kernel emit a PERF_RECORD_LOST_SAMPLES record with
the number of possible discarded records when it is impossible to demux
the samples.
It makes sure the user is not left in the dark about such discards.
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1431285195-14269-8-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the PEBS interrupt threshold is larger than one record and the
machine supports multiple PEBS events, the records of these events are
mixed up and we need to demultiplex them.
Demuxing the records is hard because the hardware is deficient. The
hardware has two issues that, when combined, create impossible
scenarios to demux.
The first issue is that the 'status' field of the PEBS record is a copy
of the GLOBAL_STATUS MSR at PEBS assist time. To see why this is a
problem let us first describe the regular PEBS cycle:
A) the CTRn value reaches 0:
- the corresponding bit in GLOBAL_STATUS gets set
- we start arming the hardware assist
< some unspecified amount of time later -- this could cover multiple
events of interest >
B) the hardware assist is armed, any next event will trigger it
C) a matching event happens:
- the hardware assist triggers and generates a PEBS record
this includes a copy of GLOBAL_STATUS at this moment
- if we auto-reload we (re)set CTRn
- we clear the relevant bit in GLOBAL_STATUS
Now consider the following chain of events:
A0, B0, A1, C0
The event generated for counter 0 will include a status with counter 1
set, even though its not at all related to the record. A similar thing
can happen with a !PEBS event if it just happens to overflow at the
right moment.
The second issue is that the hardware will only emit one record for two
or more counters if the event that triggers the assist is 'close'. The
'close' can be several cycles. In some cases even the complete assist,
if the event is something that doesn't need retirement.
For instance, consider this chain of events:
A0, B0, A1, B1, C01
Where C01 is an event that triggers both hardware assists, we will
generate but a single record, but again with both counters listed in the
status field.
This time the record pertains to both events.
Note that these two cases are different but undistinguishable with the
data as generated. Therefore demuxing records with multiple PEBS bits
(we can safely ignore status bits for !PEBS counters) is impossible.
Furthermore we cannot emit the record to both events because that might
cause a data leak -- the events might not have the same privileges -- so
what this patch does is discard such events.
The assumption/hope is that such discards will be rare.
Here lists some possible ways you may get high discard rate.
- when you count the same thing multiple times. But it is not a useful
configuration.
- you can be unfortunate if you measure with a userspace only PEBS
event along with either a kernel or unrestricted PEBS event. Imagine
the event triggering and setting the overflow flag right before
entering the kernel. Then all kernel side events will end up with
multiple bits set.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
[ Changelog improvements. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1430940834-8964-4-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Changeset a43455a1d5 ("sched/numa: Ensure task_numa_migrate() checks
the preferred node") fixes an issue where workloads would never
converge on a fully loaded (or overloaded) system.
However, it introduces a regression on less than fully loaded systems,
where workloads converge on a few NUMA nodes, instead of properly
staying spread out across the whole system. This leads to a reduction
in available memory bandwidth, and usable CPU cache, with predictable
performance problems.
The root cause appears to be an interaction between the load balancer
and NUMA balancing, where the short term load represented by the load
balancer differs from the long term load the NUMA balancing code would
like to base its decisions on.
Simply reverting a43455a1d5 would re-introduce the non-convergence
of workloads on fully loaded systems, so that is not a good option. As
an aside, the check done before a43455a1d5 only applied to a task's
preferred node, not to other candidate nodes in the system, so the
converge-on-too-few-nodes problem still happens, just to a lesser
degree.
Instead, try to compensate for the impedance mismatch between the load
balancer and NUMA balancing by only ever considering a lesser loaded
node as a destination for NUMA balancing, regardless of whether the
task is trying to move to the preferred node, or to another node.
This patch also addresses the issue that a system with a single
runnable thread would never migrate that thread to near its memory,
introduced by 095bebf61a ("sched/numa: Do not move past the balance
point if unbalanced").
A test where the main thread creates a large memory area, and spawns a
worker thread to iterate over the memory (placed on another node by
select_task_rq_fair), after which the main thread goes to sleep and
waits for the worker thread to loop over all the memory now sees the
worker thread migrated to where the memory is, instead of having all
the memory migrated over like before.
Jirka has run a number of performance tests on several systems: single
instance SpecJBB 2005 performance is 7-15% higher on a 4 node system,
with higher gains on systems with more cores per socket.
Multi-instance SpecJBB 2005 (one per node), linpack, and stream see
little or no changes with the revert of 095bebf61a and this patch.
Reported-by: Artem Bityutski <dedekind1@gmail.com>
Reported-by: Jirka Hladky <jhladky@redhat.com>
Tested-by: Jirka Hladky <jhladky@redhat.com>
Tested-by: Artem Bityutskiy <dedekind1@gmail.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150528095249.3083ade0@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 095bebf61a ("sched/numa: Do not move past the balance point
if unbalanced") broke convergence of workloads with just one runnable
thread, by making it impossible for the one runnable thread on the
system to move from one NUMA node to another.
Instead, the thread would remain where it was, and pull all the memory
across to its location, which is much slower than just migrating the
thread to where the memory is.
The next patch has a better fix for the issue that 095bebf61a tried
to address.
Reported-by: Jirka Hladky <jhladky@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dedekind1@gmail.com
Cc: mgorman@suse.de
Link: http://lkml.kernel.org/r/1432753468-7785-2-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The optimized task selection logic optimistically selects a new task
to run without first doing a full put_prev_task(). This is so that we
can avoid a put/set on the common ancestors of the old and new task.
Similarly, we should only call check_cfs_rq_runtime() to throttle
eligible groups if they're part of the common ancestry, otherwise it
is possible to end up with no eligible task in the simple task
selection.
Imagine:
/root
/prev /next
/A /B
If our optimistic selection ends up throttling /next, we goto simple
and our put_prev_task() ends up throttling /prev, after which we're
going to bug out in set_next_entity() because there aren't any tasks
left.
Avoid this scenario by only throttling common ancestors.
Reported-by: Mohammed Naser <mnaser@vexxhost.com>
Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Ben Segall <bsegall@google.com>
[ munged Changelog ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pjt@google.com
Fixes: 678d5718d8 ("sched/fair: Optimize cgroup pick_next_task_fair()")
Link: http://lkml.kernel.org/r/xm26wq1oswoq.fsf@sword-of-the-dawn.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
preempt_schedule_context() is a tracing safe preemption point but it's
only used when CONFIG_CONTEXT_TRACKING=y. Other configs have tracing
recursion issues since commit:
b30f0e3ffe ("sched/preempt: Optimize preemption operations on __schedule() callers")
introduced function based preemp_count_*() ops.
Lets make it available on all configs and give it a more appropriate
name for its new position.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1433432349-1021-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since function tracing disables preemption, it needs a safe preemption
point to use when preemption is re-enabled without worrying about tracing
recursion. Ie: to avoid tracing recursion, that preemption point can't
be traced (use of notrace qualifier) and it can't call any traceable
function before that preemption point disables preemption itself, which
disarms the recursion.
preempt_schedule() was fine until commit:
b30f0e3ffe ("sched/preempt: Optimize preemption operations on __schedule() callers")
because PREEMPT_ACTIVE (which has the property to disable preemption
and this disarm tracing preemption recursion) was set before calling
any further function.
But that commit introduced the use of preempt_count_add/sub() functions
to set PREEMPT_ACTIVE and because these functions are called before
preemption gets a chance to be disabled, we have a tracing recursion.
preempt_schedule_context() is one of the possible preemption functions
used by tracing. Its special purpose is to avoid tracing recursion
against context tracking. Lets enhance this function to become more
generally tracing safe by disabling preemption with raw accessors, such
that no function is called before preemption gets disabled and disarm
the tracing recursion.
This function is going to become the specific tracing-safe preemption
point in further commit.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1433432349-1021-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The lock_class iteration of /proc/lock_stat is not serialized against
the lockdep_free_key_range() call from module unload.
Therefore it can happen that we find a class of which ->name/->key are
no longer valid.
There is a further bug in zap_class() that left ->name dangling. Cure
this. Use RCU_INIT_POINTER() because NULL.
Since lockdep_free_key_range() is rcu_sched serialized, we can read
both ->name and ->key under rcu_read_lock_sched() (preempt-disable)
and be assured that if we observe a !NULL value it stays safe to use
for as long as we hold that lock.
If we observe both NULL, skip the entry.
Reported-by: Jerome Marchand <jmarchan@redhat.com>
Tested-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150602105013.GS3644@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf fixes from Ingo Molnar:
"The biggest chunk of the changes are two regression fixes: a HT
workaround fix and an event-group scheduling fix. It's been verified
with 5 days of fuzzer testing.
Other fixes:
- eBPF fix
- a BIOS breakage detection fix
- PMU driver fixes"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel/pt: Fix a refactoring bug
perf/x86: Tweak broken BIOS rules during check_hw_exists()
perf/x86/intel/pt: Untangle pt_buffer_reset_markers()
perf: Disallow sparse AUX allocations for non-SG PMUs in overwrite mode
perf/x86: Improve HT workaround GP counter constraint
perf/x86: Fix event/group validation
perf: Fix race in BPF program unregister
In the functions compat_get_bitmap() and compat_put_bitmap() the
variable nr_compat_longs stores how many compat_ulong_t words should be
copied in a loop.
The copy loop itself is this:
if (nr_compat_longs-- > 0) {
if (__get_user(um, umask)) return -EFAULT;
} else {
um = 0;
}
Since nr_compat_longs gets unconditionally decremented in each loop and
since it's type is unsigned this could theoretically lead to out of
bounds accesses to userspace if nr_compat_longs wraps around to
(unsigned)(-1).
Although the callers currently do not trigger out-of-bounds accesses, we
should better implement the loop in a safe way to completely avoid such
warp-arounds.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Remove the line-break in the user-visible string and add the
missing space in this error message:
WARNING: lockdep init error! lock-(console_sem).lock was acquiredbefore lockdep_init
Also:
- don't yell, it's just a debug warning
- denote references to function calls with '()'
- standardize the lock name quoting
- and finish the sentence.
The result:
WARNING: lockdep init error: lock '(console_sem).lock' was acquired before lockdep_init().
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150602133827.GD19887@pd.tnic
[ Added a few more stylistic tweaks to the error message. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The list of loaded modules is walked through in
module_kallsyms_on_each_symbol (called by kallsyms_on_each_symbol). The
module_mutex lock should be acquired to prevent potential corruptions
in the list.
This was uncovered with new lockdep asserts in module code introduced by
the commit 0be964be0d ("module: Sanitize RCU usage and locking") in
recent next- trees.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The only sensible way to make abuse of core internal fields obvious
and easy to grep for.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
We want to rename dev->state, so provide proper get and set
functions. Rename clockevents_set_state() to
clockevents_switch_state() to avoid confusion.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Pull RCU changes from Paul E. McKenney:
- Initialization/Kconfig updates: hide most Kconfig options from unsuspecting users.
There's now a single high level configuration option:
*
* RCU Subsystem
*
Make expert-level adjustments to RCU configuration (RCU_EXPERT) [N/y/?] (NEW)
Which if answered in the negative, leaves us with a single interactive
configuration option:
Offload RCU callback processing from boot-selected CPUs (RCU_NOCB_CPU) [N/y/?] (NEW)
All the rest of the RCU options are configured automatically.
- Remove all uses of RCU-protected array indexes: replace the
rcu_[access|dereference]_index_check() APIs with READ_ONCE() and rcu_lockdep_assert().
- RCU CPU-hotplug cleanups.
- Updates to Tiny RCU: a race fix and further code shrinkage.
- RCU torture-testing updates: fixes, speedups, cleanups and
documentation updates.
- Miscellaneous fixes.
- Documentation updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Two fixes which got lost in my recent distraction. One is a weird
cpumask function which needed to be rewritten, the other is a module
bug which is cc:stable.
Thanks,
Rusty.
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Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull fixes for cpumask and modules from Rusty Russell:
"** NOW WITH TESTING! **
Two fixes which got lost in my recent distraction. One is a weird
cpumask function which needed to be rewritten, the other is a module
bug which is cc:stable"
* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
cpumask_set_cpu_local_first => cpumask_local_spread, lament
module: Call module notifier on failure after complete_formation()
The current rcutorture testing does not do any cleanup operations.
This works because the srcu_struct is statically allocated, but it
does represent a memory leak of the associated dynamically allocated
->per_cpu_ref per-CPU variables. However, rcutorture currently uses
a statically allocated srcu_struct, which cannot legally be passed to
cleanup_srcu_struct(). Therefore, this commit adds a second form
of srcu (called srcud) that dynamically allocates and frees the
associated per-CPU variables. This commit also adds a ->cleanup()
member to rcu_torture_ops that is invoked at the end of the test,
after ->cb_barriers(). This ->cleanup() pointer is NULL for all
existing tests, and thus only used for scrud. Finally, the SRCU-P
torture-test configuration selects scrud instead of srcu, with SRCU-N
continuing to use srcu, thereby testing both static and dynamic
srcu_struct structures.
Reported-by: "Ahmed, Iftekhar" <ahmedi@onid.oregonstate.edu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
The rcutorture.c file uses several explicit memory barriers that can
easily be converted to smp_store_release() and smp_load_acquire(), which
improves maintainability and also improves performance a bit.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
The locktorture long delays are in milliseconds rather than microseconds,
so this commit changes the name of the corresponding variable from
longdelay_us to longdelay_ms.
Reported-by: Ben Goodwyn <bgoodwyn@softnas.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
By default, with rcutorture.nreaders equal to -1, rcutorture provisions
N-1 reader kthreads, where N is the number of CPUs. This avoids
rcutorture-induced stalls, but also avoids heavier levels of torture.
This commit therefore allows negative values of rcutorture.nreaders
to specify larger numbers of reader kthreads, so that for example
rcutorture.nreaders=-2 provisions N kthreads and rcutorture.nreaders=-5
provisions N+3 kthreads.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Update documentation, as suggested by Josh Triplett. ]
torture_rwlock_read_unlock_irq() must use read_unlock_irqrestore()
instead of write_unlock_irqrestore().
Use read_unlock_irqrestore() instead of write_unlock_irqrestore().
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
If, at the time __rcu_process_callbacks() is invoked, there are callbacks
in Tiny RCU's callback list, but none of them are ready to be invoked,
the current list-management code will knit the non-ready callbacks out
of the list. This can result in hangs and possibly worse. This commit
therefore inserts a check for there being no callbacks that can be
invoked immediately.
This bug is unlikely to occur -- you have to get a new callback between
the time rcu_sched_qs() or rcu_bh_qs() was called, but before we get to
__rcu_process_callbacks(). It was detected by the addition of RCU-bh
testing to rcutorture, which in turn was instigated by Iftekhar Ahmed's
mutation testing. Although this bug was made much more likely by
915e8a4fe4 (rcu: Remove fastpath from __rcu_process_callbacks()), this
did not cause the bug, but rather made it much more probable. That
said, it takes more than 40 hours of rcutorture testing, on average,
for this bug to appear, so this fix cannot be considered an emergency.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
The Tiny RCU counterparts to rcu_idle_enter(), rcu_idle_exit(),
rcu_irq_enter(), and rcu_irq_exit() are empty functions, but each has
EXPORT_SYMBOL_GPL(), which needlessly consumes extra memory, especially
in kernels built with module support. This commit therefore moves these
functions to static inlines in rcutiny.h, removing the need for exports.
This won't affect the size of the tiniest kernels, which are likely
built without module support, but might help semi-tiny kernels that
might include module support.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit applies some warning-omission micro-optimizations to RCU's
various extended-quiescent-state functions, which are on the kernel/user
hotpath for CONFIG_NO_HZ_FULL=y.
Reported-by: Rik van Riel <riel@redhat.com>
Reported by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit updates the initialization of the kthread_prio boot parameter
so that RCU will build even when CONFIG_RCU_KTHREAD_PRIO is undefined.
The kthread_prio boot parameter is set to CONFIG_RCU_KTHREAD_PRIO if
that is defined, otherwise to 1 if CONFIG_RCU_BOOST is defined and
to zero otherwise. This commit then makes CONFIG_RCU_KTHREAD_PRIO
depend on CONFIG_RCU_EXPERT, so that Kconfig users won't be asked about
CONFIG_RCU_KTHREAD_PRIO unless they want to be.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
This commit introduces an RCU_FANOUT_LEAF C-preprocessor macro so
that RCU will build even when CONFIG_RCU_FANOUT_LEAF is undefined.
The RCU_FANOUT_LEAF macro is set to the value of CONFIG_RCU_FANOUT_LEAF
when defined, otherwise it is set to 32 for 32-bit systems and 64 for
64-bit systems. This commit then makes CONFIG_RCU_FANOUT_LEAF depend
on CONFIG_RCU_EXPERT, so that Kconfig users won't be asked about
CONFIG_RCU_FANOUT_LEAF unless they want to be.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
This commit introduces an RCU_FANOUT C-preprocessor macro so that RCU will
build even when CONFIG_RCU_FANOUT is undefined. The RCU_FANOUT macro is
set to the value of CONFIG_RCU_FANOUT when defined, otherwise it is set
to 32 for 32-bit systems and 64 for 64-bit systems. This commit then
makes CONFIG_RCU_FANOUT depend on CONFIG_RCU_EXPERT, so that Kconfig
users won't be asked about CONFIG_RCU_FANOUT unless they want to be.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
The purpose of this commit is to make it easier to verify that RCU's
combining tree is set up correctly, which is useful to have when making
changes in how that tree is initialized.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
[ paulmck: Fold fix found by Fengguang's 0-day test robot. ]
The CONFIG_RCU_FANOUT_EXACT Kconfig parameter is used primarily (and
perhaps only) by rcutorture to verify that RCU works correctly in specific
rcu_node combining-tree configurations. It therefore does not make
much sense have this as a question to people attempting to configure
their kernels. So this commit creates an rcutree.rcu_fanout_exact=
boot parameter that rcutorture can use, and eliminates the original
CONFIG_RCU_FANOUT_EXACT Kconfig parameter.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Grace-period scans of the rcu_node combining tree normally
proceed quite quickly, so that it is very difficult to reproduce
races against them. This commit therefore allows grace-period
pre-initialization and cleanup to be artificially slowed down,
increasing race-reproduction probability. A pair of pairs of new
Kconfig parameters are provided, RCU_TORTURE_TEST_SLOW_PREINIT to
enable the slowing down of propagating CPU-hotplug changes up the
combining tree along with RCU_TORTURE_TEST_SLOW_PREINIT_DELAY to
specify the delay in jiffies, and RCU_TORTURE_TEST_SLOW_CLEANUP
to enable the slowing down of the end-of-grace-period cleanup scan
along with RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY to specify the delay
in jiffies. Boot-time parameters named rcutree.gp_preinit_delay and
rcutree.gp_cleanup_delay allow these delays to be specified at boot time.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Because gcc doesn't realize that rcu_num_lvls must be strictly greater
than zero, some versions give a spurious warning about levelcnt[0] being
uninitialized in rcu_init_one(). This commit updates the condition on
the pre-existing panic() in order to educate gcc on this point.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, the larger the gp_init_delay boot parameter, the slower
rcutorture will sequence through grace periods. This commit avoids this
issue by decreasing the probability of slowing initialization of a given
grace period as the degree of slowness increases.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
We removed __cpuinit support (leaving no-op stubs) quite some time ago.
However a new instance was added in commit 00df35f991
("cpu: Defer smpboot kthread unparking until CPU known to scheduler")
Since we want to clobber the stubs soon, get this removed now.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit 00df35f991 (cpu: Defer smpboot kthread unparking until CPU known
to scheduler) put the online path's call to smpboot_unpark_threads()
into a CPU-hotplug notifier. This commit places the offline-failure
paths call into the same notifier for the sake of uniformity.
Note that it is not currently possible to place the offline path's call to
smpboot_park_threads() into an existing notifier because the CPU_DYING
notifiers run in a restricted environment, and the CPU_UP_PREPARE
notifiers run too soon.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcu_data structure's ->rcu_qs_ctr_snap field is initialized at
CPU-online time from the current CPU's element of the per-CPU rcu_qs_ctr
variable. Unfortunately, this is at CPU_UP_PREPARE time, so has nothing
to do with the CPU being onlined. This commit therefore initializes
this variable from the incoming CPU's element of rcu_qs_ctr.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Because offline CPUs are propagated up the rcu_node tree's ->qsmaskinit
bits just before each grace period starts, the ->qsmaskinit bit cannot
be clear when the corresponding ->qsmask bit is set. Furthermore, this
condition used to correspond to a CPU that was on its way offline, and
making RCU's notion of an offline CPU more precise has eliminated this
situation. This commit therefore removes the now-redundant offline
check from force_qs_rnp().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Because force_qs_rnp() is invoked only from the force-quiescent-state
code which runs only in the context of the grace-period kthread, a grace
period must always be in progress throughout force_qs_rnp()'s execution.
This commit therefore removes the rcu_gp_in_progress() check and the
associated dead code.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tasks are no longer migrated away from a given rcu_node structure
when all CPUs corresponding to that rcu_node structure have gone offline.
This means that rcu_read_unlock_special() no longer needs to loop
retrying rcu_node ->lock acquisition because the current task is
guaranteed to stay put.
This commit takes a small and paranoid step towards relying on this
guarantee by placing a WARN_ON_ONCE() just after the early exit from
the lock-acquisition loop.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit removes a HOTPLUG_CPU #ifdef, replacing it with
IS_ENABLED()-protected return statements. This relies on the
optimizer to remove any resulting dead code.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
rcu_cpu_has_callbacks() is declared int. The current declaration was introduced
in commit c0f4dfd4f9 (rcu: Make RCU_FAST_NO_HZ take advantage of numbered
callbacks). But it is actually returning bool and as the function description
states " * Return true if the specified CPU has any callback....", this probably
should be a bool as all (3) call-sites currently treat it as bool.
Type-checking coccinelle spatches are being used to locate type mismatches
between function signatures and return values in this case this produced:
./kernel/rcu/tree.c:3538 WARNING: return of wrong type
int != bool,
Patch was compile tested with x86_64_defconfig (implies CONFIG_TREE_RCU=y)
Patch is against 4.1-rc3 (localversion-next is -next-20150511) and fixes
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
rcu_bh_data, rcu_sched_data and rcu_preempt_data are never used outside
kernel/rcu/tree.c and thus can be made static.
Doing so fixes a section mismatch warning reported by clang when
building LLVMLinux with -Wsection, because these variables were declared
in .data..percpu and defined in .data..percpu..shared_aligned since
commit 11bbb235c2 ("rcu: Use DEFINE_PER_CPU_SHARED_ALIGNED for
rcu_data").
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Currently, synchronize_sched_expedited() will call synchronize_sched()
if there is danger of counter wrap. But if configuration says to
always do expedited grace periods, synchronize_sched() will just
call synchronize_sched_expedited() right back again. In theory,
the old expedited operations will complete, the counters will
get back in synch, and the recursion will end. But we could
easily run out of stack long before that time. This commit
therefore makes synchronize_sched_expedited() invoke the underlying
wait_rcu_gp(call_rcu_sched) instead of synchronize_sched(), the same as
all the other calls out from synchronize_sched_expedited().
This bug was introduced by commit 1924bcb025 (Avoid counter wrap in
synchronize_sched_expedited()).
Reported-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The current formulation of control dependencies fails on DEC Alpha,
which does not respect dependencies of any kind unless an explicit
memory barrier is provided. This means that the current fomulation of
control dependencies fails on Alpha. This commit therefore creates a
READ_ONCE_CTRL() that has the same overhead on non-Alpha systems, but
causes Alpha to produce the needed ordering. This commit also applies
READ_ONCE_CTRL() to the one known use of control dependencies.
Use of READ_ONCE_CTRL() also has the beneficial effect of adding a bit
of self-documentation to control dependencies.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit adds grace number and command-flags information to the
"kthread starved" message that is sometimes printed out as part of
RCU CPU stall warnings. This message is caused by the corresponding
RCU grace-period kthread not having run for at least two seconds, and
this added information can be helpful when debugging.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The first item list_for_each_entry_continue(alist) iterates over is
alist->next, rather than alist itself. Consequently,
rcu_print_detail_task_stall_rnp() skips the task referenced by gp_tasks.
Use gp_tasks->prev as the argument to list_for_each_entry_continue()
instead.
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Use the normal return values for bool functions
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcu_gp_kthread_wake() refuses to do a wakeup unless at least
one of the ->gp_flags bits are set, which normally will not be the
case when the last quiescent state is reported. This results in
up to a 3-jiffy delay given default Kconfig settings. This commit
therefore has rcu_report_qs_rsp() set RCU_GP_FLAG_FQS before invoking
rcu_gp_kthread_wake() in order to force a more immediate wakeup at
grace-period end, thus reducing grace-period latencies.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit converts several CONFIG_RCU_NOCB_CPU_ALL #ifdefs to
instead use IS_ENABLED(). This change should help avoid hiding
code from compiler diagnostics.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit creates an immutable rcu_data_p pointer that references
rcu_preempt_data for TREE_PREEMPT_RCU builds and that references
rcu_sched_data for TREE_RCU builds. This rcu_data_p pointer will enable
more code to move from #ifdef to IS_ENABLED().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds a "const" tag to the declarations of rcu_state_p,
which should allow the compiler to generate better code and also to
catch erroneous assignments to this variable.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit removes a few RCU_BOOST #ifdefs, replacing them with
IS_ENABLED()-protected return statements. This relies on the
optimizer to remove any resulting dead code. There are several other
RCU_BOOST #ifdefs, however these rely on some per-CPU variables that
are available only under RCU_BOOST. These might be converted later,
if the simplification proves to outweigh the increase in memory footprint.
One hoped-for advantage is more easily locating compiler errors in
obscure combinations of Kconfig parameters.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <linux-rt-users@vger.kernel.org>
It would be good to move more code from #ifdef to IS_ENABLED(), but
that does not work if the body of the IS_ENABLED() "if" statement
references a variable (such as rcu_preempt_state) that does not
exist if the IS_ENABLED() Kconfig variable is not set. This commit
therefore substitutes *rcu_state_p for all uses of rcu_preempt_state
in kernel/rcu/tree_preempt.h, which should enable elimination of
a few #ifdefs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE()
and WRITE_ONCE() APIs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updated to include kernel/torture.c as suggested by Jason Low. ]
PMUs that don't support hardware scatter tables require big contiguous
chunks of memory and a PMI to switch between them. However, in overwrite
using a PMI for this purpose adds extra overhead that the users would
like to avoid. Thus, in overwrite mode for such PMUs we can only allow
one contiguous chunk for the entire requested buffer.
This patch changes the behavior accordingly, so that if the buddy allocator
fails to come up with a single high-order chunk for the entire requested
buffer, the allocation will fail.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@infradead.org
Cc: adrian.hunter@intel.com
Cc: hpa@zytor.com
Link: http://lkml.kernel.org/r/1432308626-18845-2-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
there is a race between perf_event_free_bpf_prog() and free_trace_kprobe():
__free_event()
event->destroy(event)
tp_perf_event_destroy()
perf_trace_destroy()
perf_trace_event_unreg()
which is dropping event->tp_event->perf_refcount and allows to proceed in:
unregister_trace_kprobe()
unregister_kprobe_event()
trace_remove_event_call()
probe_remove_event_call()
free_trace_kprobe()
while __free_event does:
call_rcu(&event->rcu_head, free_event_rcu);
free_event_rcu()
perf_event_free_bpf_prog()
To fix the race simply move perf_event_free_bpf_prog() before
event->destroy(), since event->tp_event is still valid at that point.
Note, perf_trace_destroy() is not racing with trace_remove_event_call()
since they both grab event_mutex.
Reported-by: Wang Nan <wangnan0@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lizefan@huawei.com
Cc: pi3orama@163.com
Fixes: 2541517c32 ("tracing, perf: Implement BPF programs attached to kprobes")
Link: http://lkml.kernel.org/r/1431717321-28772-1-git-send-email-ast@plumgrid.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is no point in calling suspend/resume for unused clockevents as
they are already stopped and disabled.
This is really important for AT91 as the hardware is a trainwreck and
takes ages to synchronize.
Reported-by: Sylvain Rochet <sylvain.rochet@finsecur.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1421399151-26800-1-git-send-email-alexandre.belloni@free-electrons.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull timer fix from Thomas Gleixner:
"One more fix from the timer departement:
- Handle division of negative nanosecond values proper on 32bit.
A recent cleanup wrecked the sign handling of the dividend and
dropped the check for negative divisors"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ktime: Fix ktime_divns to do signed division
Pull block fixes from Jens Axboe:
"Three small fixes that have been picked up the last few weeks.
Specifically:
- Fix a memory corruption issue in NVMe with malignant user
constructed request. From Christoph.
- Kill (now) unused blk_queue_bio(), dm was changed to not need this
anymore. From Mike Snitzer.
- Always use blk_schedule_flush_plug() from the io_schedule() path
when flushing a plug, fixing a !TASK_RUNNING warning with md. From
Shaohua"
* 'for-linus' of git://git.kernel.dk/linux-block:
sched: always use blk_schedule_flush_plug in io_schedule_out
nvme: fix kernel memory corruption with short INQUIRY buffers
block: remove export for blk_queue_bio
Now that we have a read_boot_clock64() function available on every
architecture, and converted all the users to it, it's time to remove
the (now unused) read_boot_clock() completely from the kernel.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
[jstultz: Minor commit message tweak suggested by Ingo]
Signed-off-by: John Stultz <john.stultz@linaro.org>
The timer_start event now shows whether the timer is
deferrable in case of a low-res timer. The debug_activate
function now includes a deferrable flag while calling
the trace_timer_start event.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
[jstultz: Fixed minor whitespace and grammer tweaks
pointed out by Ingo]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Ingo suggested that the timekeeping debugging variables
recently added should not be global, and should be tied
to the timekeeper's read_base.
Thus this patch implements that suggestion.
This version is different from the earlier versions
as it keeps the variables in the timekeeper structure
rather then in the tkr.
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This patch series introduces a new function
u32 ktime_get_resolution_ns(void)
which allows to clean up some driver code.
In particular the IIO subsystem has a function to provide timestamps for
events but no means to get their resolution. So currently the dht11 driver
tries to guess the resolution in a rather messy and convoluted way. We
can do much better with the new code.
This API is not designed to be exposed to user space.
This has been tested on i386, sunxi and mxs.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Harald Geyer <harald@ccbib.org>
[jstultz: Tweaked to make it build after upstream changes]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Invalid values may overflow later, leading to undefined behaviour when
multiplied by 60 to get the amount of seconds.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
If no_irq_chip is used for wake up (e.g. gpio-keys with a simple GPIO
controller), the following warning is printed on resume from s2ram:
WANING: CPU: 0 PID: 1046 at kernel/irq/manage.c:537 irq_set_irq_wake+0x9c/0xf8()
Unbalanced IRQ 113 wake disable
This happens because no_irq_chip does not implement
irq_chip.irq_set_wake(), causing set_irq_wake_real() to return -ENXIO,
and irq_set_irq_wake() to reset the wake_depth to zero.
Set IRQCHIP_SKIP_SET_WAKE to indicate that irq_chip.irq_set_wake() is
not implemented.
Cfr. commit 10a50f1ab5 ("genirq: Set IRQCHIP_SKIP_SET_WAKE flag
for dummy_irq_chip").
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Roger Quadros <rogerq@ti.com>
Cc: Gregory Clement <gregory.clement@free-electrons.com>
Link: http://lkml.kernel.org/r/1432281529-23325-1-git-send-email-geert%2Brenesas@glider.be
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
klp_for_each_object and klp_for_each_func are now used all over the
code. One need not think what is the proper condition to check in the
for loop now.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Make kobj variable (of type struct kobject) statically allocated in
klp_object structure. It will allow us to move in the func-object-patch
hierarchy through kobject links.
The only reason to have it dynamic was to not have empty release
callback in the code. However we have empty callbacks for function and
patch in the code now, so it is no longer valid and the advantage of
static allocation is clear.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Commit ab992dc38f ("watchdog: Fix merge 'conflict'") has introduced an
obvious deadlock because of a typo. watchdog_proc_mutex should be
unlocked on exit.
Thanks to Miroslav Benes who was staring at the code with me and noticed
this.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Duh-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To avoid getting spurious interrupts on a tickless CPU, clockevent
device can now be stopped by switching to ONESHOT_STOPPED state.
The natural place for handling this transition is tick_program_event().
On 'expires == KTIME_MAX', we skip programming the event and so we need
to fix such call sites as well, to always call tick_program_event()
irrespective of the expires value.
Once the clockevent device is required again, check if it was earlier
put into ONESHOT_STOPPED state. If yes, switch its state to ONESHOT
before programming its event.
To make sure we haven't missed any corner case, add a WARN() for the
case where we try to reprogram clockevent device while we aren't
configured in ONESHOT_STOPPED state.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/5146b07be7f0bc497e0ebae036590ec2fa73e540.1428031396.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When no timers/hrtimers are pending, the expiry time is set to a
special value: 'KTIME_MAX'. This normally happens with
NO_HZ_{IDLE|FULL} in both LOWRES/HIGHRES modes.
When 'expiry == KTIME_MAX', we either cancel the 'tick-sched' hrtimer
(NOHZ_MODE_HIGHRES) or skip reprogramming clockevent device
(NOHZ_MODE_LOWRES). But, the clockevent device is already
reprogrammed from the tick-handler for next tick.
As the clock event device is programmed in ONESHOT mode it will at
least fire one more time (unnecessarily). Timers on few
implementations (like arm_arch_timer, etc.) only support PERIODIC mode
and their drivers emulate ONESHOT over that. Which means that on these
platforms we will get spurious interrupts periodically (at last
programmed interval rate, normally tick rate).
In order to avoid spurious interrupts, the clockevent device should be
stopped or its interrupts should be masked.
A simple (yet hacky) solution to get this fixed could be: update
hrtimer_force_reprogram() to always reprogram clockevent device and
update clockevent drivers to STOP generating events (or delay it to
max time) when 'expires' is set to KTIME_MAX. But the drawback here is
that every clockevent driver has to be hacked for this particular case
and its very easy for new ones to miss this.
However, Thomas suggested to add an optional state ONESHOT_STOPPED to
solve this problem: lkml.org/lkml/2014/5/9/508.
This patch adds support for ONESHOT_STOPPED state in clockevents
core. It will only be available to drivers that implement the
state-specific callbacks instead of the legacy ->set_mode() callback.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/b8b383a03ac07b13312c16850b5106b82e4245b5.1428031396.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
With Posted-Interrupts support in Intel CPU and IOMMU, an external
interrupt from assigned-devices could be directly delivered to a
virtual CPU in a virtual machine. Instead of hacking KVM and Intel
IOMMU drivers, we propose a platform independent interface to target
an interrupt to a specific virtual CPU in a virtual machine, or set
virtual CPU affinity for an interrupt.
By adopting this new interface and the hierarchy irqdomain, we could
easily support posted-interrupts on Intel platforms, and also provide
flexible enough interfaces for other platforms to support similar
features.
Here is the usage scenario for this interface:
Guest update MSI/MSI-X interrupt configuration
-->QEMU and KVM handle this
-->KVM call this interface (passing posted interrupts descriptor
and guest vector)
-->irq core will transfer the control to IOMMU
-->IOMMU will do the real work of updating IRTE (IRTE has new
format for VT-d Posted-Interrupts)
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Feng Wu <feng.wu@intel.com>
Link: http://lkml.kernel.org/r/1432026437-16560-2-git-send-email-feng.wu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
