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Sebastian Andrzej Siewior e708d7ad80 perf: Do poll_wait() before checking condition in perf_poll() 
One should first enqueue to the waitqueue and then check for the
condition. If the condition gets true after mutex_unlock() but before
poll_wait() then we lose it and would have wait for another wakeup.

This has been like this since v2.6.31-rc1 commit c7138f37f9 ("perf_counter:
fix perf_poll()"). Before that it was slightly worse. I guess we get enough
wakeups so if we miss here one it doesn't really matter. It is still a
bad example.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1407159068-1478-1-git-send-email-bigeasy@linutronix.de
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-08-13 07:51:11 +02:00
..
debug kernel/printk: use symbolic defines for console loglevels 2014-06-04 16:54:17 -07:00
events perf: Do poll_wait() before checking condition in perf_poll() 2014-08-13 07:51:11 +02:00
gcov gcov: add support for GCC 4.9 2014-06-10 15:34:46 -07:00
irq genirq: Fix memory leak when calling irq_free_hwirqs() 2014-07-05 21:42:08 +02:00
locking arch, locking: Ciao arch_mutex_cpu_relax() 2014-07-17 12:32:47 +02:00
power This pull request has a lot of work done. The main thing is the changes 2014-08-04 11:50:00 -07:00
printk kernel/printk/printk.c: revert "printk: enable interrupts before calling console_trylock_for_printk()" 2014-07-03 09:21:54 -07:00
rcu Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-04 15:55:08 -07:00
sched Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-04 16:23:30 -07:00
time Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-04 16:23:30 -07:00
trace Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-04 16:09:53 -07:00
.gitignore Ignore generated file kernel/x509_certificate_list 2013-12-10 18:21:34 +00:00
acct.c ipc, kernel: clear whitespace 2014-06-06 16:08:14 -07:00
async.c
audit_tree.c inotify: Fix reporting of cookies for inotify events 2014-02-18 11:17:17 +01:00
audit_watch.c inotify: Fix reporting of cookies for inotify events 2014-02-18 11:17:17 +01:00
audit.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
audit.h audit: Use struct net not pid_t to remember the network namespce to reply in 2014-03-20 10:10:53 -04:00
auditfilter.c Merge git://git.infradead.org/users/eparis/audit 2014-04-12 12:38:53 -07:00
auditsc.c auditsc: audit_krule mask accesses need bounds checking 2014-06-10 08:44:40 -07:00
backtracetest.c kernel/backtracetest.c: replace no level printk by pr_info() 2014-06-04 16:54:14 -07:00
bounds.c mm: do not allocate page->ptl dynamically, if spinlock_t fits to long 2013-12-20 12:25:45 -08:00
capability.c fs,userns: Change inode_capable to capable_wrt_inode_uidgid 2014-06-10 13:57:22 -07:00
cgroup_freezer.c cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes 2014-07-15 11:05:09 -04:00
cgroup.c Merge branch 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-08-04 10:11:28 -07:00
compat.c kernel/compat.c: use sizeof() instead of sizeof 2014-06-04 16:54:19 -07:00
configs.c
context_tracking.c x86/kprobes: Fix build errors and blacklist context_track_user 2014-06-14 09:07:44 +02:00
cpu_pm.c
cpu.c sched: Rework check_for_tasks() 2014-07-05 11:17:45 +02:00
cpuset.c Merge branch 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-08-04 10:11:28 -07:00
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c kernel/exec_domain.c: code clean-up 2014-06-04 16:54:15 -07:00
exit.c signals: mv {dis,}allow_signal() from sched.h/exit.c to signal.[ch] 2014-06-06 16:08:11 -07:00
extable.c asmlinkage: Make main_extable_sort_needed visible 2014-02-13 18:13:22 -08:00
fork.c Linux 3.16-rc5 2014-07-16 15:10:07 +02:00
freezer.c libata, freezer: avoid block device removal while system is frozen 2013-12-19 13:50:32 -05:00
futex_compat.c compat: Get rid of (get|put)_compat_time(val|spec) 2014-02-02 14:09:12 -08:00
futex.c futex: Simplify futex_lock_pi_atomic() and make it more robust 2014-06-21 22:26:24 +02:00
groups.c kernel/groups.c: remove return value of set_groups 2014-04-03 16:21:05 -07:00
hrtimer.c Merge branch 'perf/urgent' into perf/core, to resolve conflict and to prepare for new patches 2014-06-06 07:55:06 +02:00
hung_task.c kernel/hung_task.c: convert simple_strtoul to kstrtouint 2014-06-04 16:54:15 -07:00
irq_work.c irq_work: Remove BUG_ON in irq_work_run() 2014-07-05 11:17:26 +02:00
itimer.c
jump_label.c
kallsyms.c kernel: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:36:11 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/rwsem: Add CONFIG_RWSEM_SPIN_ON_OWNER 2014-07-16 14:57:13 +02:00
Kconfig.preempt
kexec.c kexec: fix build error when hugetlbfs is disabled 2014-07-30 20:09:37 -07:00
kmod.c signals: change wait_for_helper() to use kernel_sigaction() 2014-06-06 16:08:12 -07:00
kprobes.c kprobes: Skip kretprobe hit in NMI context to avoid deadlock 2014-08-08 10:38:04 +02:00
ksysfs.c kobject: Make support for uevent_helper optional. 2014-04-25 12:00:49 -07:00
kthread.c kthread_work: wake up worker only when the worker is idle 2014-07-28 14:07:52 -04:00
latencytop.c kernel/latencytop.c: convert seq_printf to seq_puts 2014-06-04 16:54:15 -07:00
Makefile Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-03-31 14:13:25 -07:00
module_signing.c
module-internal.h
module.c crypto: fips - only panic on bad/missing crypto mod signatures 2014-07-03 21:38:32 +08:00
notifier.c kprobes, notifier: Use NOKPROBE_SYMBOL macro in notifier 2014-04-24 10:26:39 +02:00
nsproxy.c
padata.c padata: Fix wrong usage of rcu_dereference() 2013-12-05 21:28:42 +08:00
panic.c kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers 2014-06-06 16:08:12 -07:00
params.c param: hand arguments after -- straight to init 2014-04-28 11:48:34 +09:30
pid_namespace.c pid_namespace: pidns_get() should check task_active_pid_ns() != NULL 2014-04-02 16:20:21 -07:00
pid.c
posix-cpu-timers.c posix-timers: Convert abuses of BUG_ON to WARN_ON 2013-12-09 16:56:29 +01:00
posix-timers.c
profile.c kernel/profile.c: use static const char instead of static char 2014-06-06 16:08:13 -07:00
ptrace.c sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
range.c
reboot.c kernel/reboot.c: convert simple_strtoul to kstrtoint 2014-06-04 16:54:15 -07:00
relay.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-04-12 14:49:50 -07:00
res_counter.c kernel/res_counter.c: replace simple_strtoull by kstrtoull 2014-06-04 16:54:15 -07:00
resource.c resources: Clarify sanity check message 2014-05-23 10:47:21 -06:00
seccomp.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
signal.c signal: Explain local_irq_save() call 2014-07-09 09:14:33 -07:00
smp.c Linux 3.16-rc5 2014-07-16 15:10:07 +02:00
smpboot.c
smpboot.h
softirq.c Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu 2014-05-22 11:36:10 +02:00
stacktrace.c
stop_machine.c kernel/stop_machine.c: kernel-doc warning fix 2014-06-04 16:54:15 -07:00
sys_ni.c sys_sgetmask/sys_ssetmask: add CONFIG_SGETMASK_SYSCALL 2014-06-04 16:54:14 -07:00
sys.c sched: Consolidate open coded implementations of nice level frobbing into nice_to_rlimit() and rlimit_to_nice() 2014-05-22 11:16:36 +02:00
sysctl_binary.c
sysctl.c kernel/watchdog.c: print traces for all cpus on lockup detection 2014-06-23 16:47:44 -07:00
system_certificates.S KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
system_keyring.c KEYS: correct alignment of system_certificate_list content in assembly file 2013-12-10 18:25:28 +00:00
task_work.c
taskstats.c
test_kprobes.c
time.c
timeconst.bc
timer.c timer: Prevent overflow in apply_slack 2014-04-30 13:46:17 +02:00
torture.c torture: Avoid format string leak to thead name 2014-07-07 10:12:56 -07:00
tracepoint.c tracing: syscall_regfunc() should not skip kernel threads 2014-06-21 00:15:26 -04:00
tsacct.c
uid16.c
up.c smp: Rename __smp_call_function_single() to smp_call_function_single_async() 2014-02-24 14:47:15 -08:00
user_namespace.c kernel/user_namespace.c: kernel-doc/checkpatch fixes 2014-06-06 16:08:13 -07:00
user-return-notifier.c
user.c kernel/user.c: drop unused field 'files' from user_struct 2014-06-04 16:54:16 -07:00
utsname_sysctl.c sysctl: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
utsname.c
watchdog.c kernel/watchdog.c: print traces for all cpus on lockup detection 2014-06-23 16:47:44 -07:00
workqueue_internal.h workqueue: rename manager_mutex to attach_mutex 2014-05-20 10:59:32 -04:00
workqueue.c Merge branch 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2014-08-04 10:09:27 -07:00