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0729e19614
kernel-ark/kernel
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Darren Hart 0729e19614 futex: Fix wakeup race by setting TASK_INTERRUPTIBLE before queue_me() 
PI futexes do not use the same plist_node_empty() test for wakeup.
It was possible for the waiter (in futex_wait_requeue_pi()) to set
TASK_INTERRUPTIBLE after the waker assigned the rtmutex to the
waiter. The waiter would then note the plist was not empty and call
schedule(). The task would not be found by any subsequeuent futex
wakeups, resulting in a userspace hang.

By moving the setting of TASK_INTERRUPTIBLE to before the call to
queue_me(), the race with the waker is eliminated. Since we no
longer call get_user() from within queue_me(), there is no need to
delay the setting of TASK_INTERRUPTIBLE until after the call to
queue_me().

The FUTEX_LOCK_PI operation is not affected as futex_lock_pi()
relies entirely on the rtmutex code to handle schedule() and
wakeup.  The requeue PI code is affected because the waiter starts
as a non-PI waiter and is woken on a PI futex.

Remove the crusty old comment about holding spinlocks() across
get_user() as we no longer do that. Correct the locking statement
with a description of why the test is performed.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Dinakar Guniguntala <dino@in.ibm.com>
Cc: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <20090922053038.8717.97838.stgit@Aeon>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-22 10:37:44 +02:00
..
gcov powerpc: Enable GCOV 2009-08-20 10:29:28 +10:00
irq Merge branch 'irq-threaded-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-11 13:21:31 -07:00
power vt: remove power stuff from kernel/power 2009-09-19 13:13:25 -07:00
time Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 09:15:24 -07:00
trace Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-21 09:06:17 -07:00
.gitignore
acct.c bsdacct: switch credentials for writing to the accounting file 2009-08-24 11:33:40 +10:00
async.c async: Fix lack of boot-time console due to insufficient synchronization 2009-06-08 12:31:53 -07:00
audit_tree.c Fix rule eviction order for AUDIT_DIR 2009-06-24 00:02:38 -04:00
audit_watch.c Audit: clean up all op= output to include string quoting 2009-06-24 00:00:52 -04:00
audit.c Fix rule eviction order for AUDIT_DIR 2009-06-24 00:02:38 -04:00
audit.h Fix rule eviction order for AUDIT_DIR 2009-06-24 00:02:38 -04:00
auditfilter.c Audit: clean up all op= output to include string quoting 2009-06-24 00:00:52 -04:00
auditsc.c Fix rule eviction order for AUDIT_DIR 2009-06-24 00:02:38 -04:00
backtracetest.c
bounds.c
capability.c
cgroup_debug.c
cgroup_freezer.c
cgroup.c writeback: add name to backing_dev_info 2009-09-11 09:20:26 +02:00
compat.c signals: implement sys_rt_tgsigqueueinfo 2009-04-30 19:24:24 +02:00
configs.c
cpu.c Merge branch 'x86-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-15 09:19:38 -07:00
cpuset.c cpuset,mm: update tasks' mems_allowed in time 2009-06-16 19:47:31 -07:00
cred-internals.h
cred.c CRED: Allow put_cred() to cope with a NULL groups list 2009-09-15 09:10:57 +10:00
delayacct.c headers: taskstats_kern.h trim 2009-09-18 09:48:52 -07:00
dma.c
exec_domain.c
exit.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-11 13:20:18 -07:00
extable.c
fork.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-11 13:20:18 -07:00
freezer.c sched: fix nr_uninterruptible accounting of frozen tasks really 2009-07-18 14:19:53 +02:00
futex_compat.c futex: Fix compat_futex to be same as futex for REQUEUE_PI 2009-08-10 15:41:12 +02:00
futex.c futex: Fix wakeup race by setting TASK_INTERRUPTIBLE before queue_me() 2009-09-22 10:37:44 +02:00
groups.c groups: move code to kernel/groups.c 2009-06-16 19:47:48 -07:00
hrtimer.c Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 09:15:24 -07:00
hung_task.c
itimer.c
kallsyms.c kernel/kallsyms.c: replace deprecated __initcall with device_initcall and fix whitespace 2009-06-09 22:37:52 +02:00
Kconfig.freezer
Kconfig.hz
Kconfig.preempt
kexec.c kexec: fix omitting offset in extended crashkernel syntax 2009-07-29 19:10:34 -07:00
kfifo.c kfifo: Use "const" definitions 2009-09-19 13:13:17 -07:00
kgdb.c sysrq, intel_fb: fix sysrq g collision 2009-05-15 07:56:24 -05:00
kmod.c Merge branch 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-11 13:24:03 -07:00
kprobes.c Merge branch 'linus' into tracing/core 2009-08-11 14:19:09 +02:00
ksysfs.c
kthread.c sched: Keep kthreads at default priority 2009-09-09 17:30:06 +02:00
latencytop.c
lockdep_internals.h lockdep: BFS cleanup 2009-07-24 10:53:29 +02:00
lockdep_proc.c Merge commit 'v2.6.31-rc8' into core/locking 2009-08-31 18:05:25 +02:00
lockdep_states.h
lockdep.c lockdep: Remove recursion stattistics 2009-08-29 13:22:36 +02:00
Makefile tracing: Remove markers 2009-09-18 21:22:08 +02:00
module.c tracing: Remove markers 2009-09-18 21:22:08 +02:00
mutex-debug.c
mutex-debug.h
mutex.c Merge branch 'linus' into perfcounters/core 2009-06-11 17:55:42 +02:00
mutex.h
notifier.c
ns_cgroup.c
nsproxy.c nsproxy: extract create_nsproxy() 2009-06-18 13:03:56 -07:00
panic.c trace: stop tracer in oops_enter() 2009-07-24 15:30:45 -04:00
params.c module_param: allow 'bool' module_params to be bool, not just int. 2009-06-12 21:46:58 +09:30
perf_counter.c perf_counter: Fix perf_copy_attr() pointer arithmetic 2009-09-19 19:32:55 +02:00
pid_namespace.c pidns: rewrite copy_pid_ns() 2009-06-18 13:03:55 -07:00
pid.c kmemleak: Remove alloc_bootmem annotations introduced in the past 2009-07-09 17:07:02 +01:00
pm_qos_params.c
posix-cpu-timers.c posix_cpu_timers_exit_group(): Do not use thread_group_cputimer() 2009-08-08 18:30:25 +02:00
posix-timers.c time: Introduce CLOCK_REALTIME_COARSE 2009-08-21 21:43:46 +02:00
printk.c cleanup console_print() 2009-09-14 17:41:42 -07:00
profile.c kernel/profile.c: Switch /proc/irq/prof_cpu_mask to seq_file 2009-09-20 20:15:40 +02:00
ptrace.c Merge branch 'master' into next 2009-07-14 00:30:40 +10:00
rcupdate.c rcu: Fix whitespace inconsistencies 2009-09-19 08:53:22 +02:00
rcutorture.c rcu: Fix whitespace inconsistencies 2009-09-19 08:53:22 +02:00
rcutree_plugin.h rcu: Fix whitespace inconsistencies 2009-09-19 08:53:22 +02:00
rcutree_trace.c rcu: Fix whitespace inconsistencies 2009-09-19 08:53:22 +02:00
rcutree.c rcu: Fix whitespace inconsistencies 2009-09-19 08:53:22 +02:00
rcutree.h rcu: Fix whitespace inconsistencies 2009-09-19 08:53:22 +02:00
relay.c
res_counter.c memcg: add interface to reset limits 2009-06-18 13:03:48 -07:00
resource.c kernel/resource.c: fix sign extension in reserve_setup() 2009-06-30 18:56:00 -07:00
rtmutex_common.h
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c rtmutex: Avoid deadlock in rt_mutex_start_proxy_lock() 2009-08-06 05:50:21 +02:00
rtmutex.h
rwsem.c
sched_clock.c sched_clock: Make it NMI safe 2009-09-18 20:47:30 +02:00
sched_cpupri.c sched: Add new prio to cpupri before removing old prio 2009-08-02 14:26:09 +02:00
sched_cpupri.h
sched_debug.c sched: Add new wakeup preemption mode: WAKEUP_RUNNING 2009-09-17 10:17:25 +02:00
sched_fair.c Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-21 09:06:17 -07:00
sched_features.h sched: Add new wakeup preemption mode: WAKEUP_RUNNING 2009-09-17 10:17:25 +02:00
sched_idletask.c sched: Simplify sys_sched_rr_get_interval() system call 2009-09-21 09:53:55 +02:00
sched_rt.c sched: Simplify sys_sched_rr_get_interval() system call 2009-09-21 09:53:55 +02:00
sched_stats.h
sched.c sched: Simplify sys_sched_rr_get_interval() system call 2009-09-21 09:53:55 +02:00
seccomp.c
semaphore.c
signal.c do_sigaltstack: small cleanups 2009-08-01 11:18:56 -07:00
slow-work.c slow-work: use round_jiffies() for thread pool's cull and OOM timers 2009-06-16 19:47:49 -07:00
smp.c Merge branch 'x86/urgent' into x86/pat 2009-08-26 17:24:28 -07:00
softirq.c softirq: add BLOCK_IOPOLL to softirq_to_name 2009-09-17 15:53:44 -04:00
softlockup.c
spinlock.c locking: Allow arch-inlined spinlocks 2009-08-31 18:08:50 +02:00
srcu.c
stacktrace.c
stop_machine.c
sys_ni.c
sys.c groups: move code to kernel/groups.c 2009-06-16 19:47:48 -07:00
sysctl_check.c
sysctl.c block: fix linkage problem with blk_iopoll and !CONFIG_BLOCK 2009-09-15 21:53:11 +02:00
taskstats.c genetlink: make netns aware 2009-07-12 14:03:27 -07:00
test_kprobes.c
time.c time: Prevent 32 bit overflow with set_normalized_timespec() 2009-09-15 10:17:30 +02:00
timeconst.pl
timer.c Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-18 09:15:24 -07:00
tracepoint.c tracing: Don't trace kernel thread syscalls 2009-08-26 21:29:52 +02:00
tsacct.c
uid16.c
up.c
user_namespace.c
user.c sched: delayed cleanup of user_struct 2009-06-15 21:30:23 -07:00
utsname_sysctl.c
utsname.c utsns: extract creeate_uts_ns() 2009-06-18 13:03:55 -07:00
wait.c locking, sched: Give waitqueue spinlocks their own lockdep classes 2009-08-10 14:43:09 +02:00
workqueue.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-11 13:23:18 -07:00