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android_kernel_google_msm/kernel
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Thomas Gleixner 307e2e09be rtmutex: Detect changes in the pi lock chain 
commit 8208498438 upstream.

When we walk the lock chain, we drop all locks after each step. So the
lock chain can change under us before we reacquire the locks. That's
harmless in principle as we just follow the wrong lock path. But it
can lead to a false positive in the dead lock detection logic:

T0 holds L0
T0 blocks on L1 held by T1
T1 blocks on L2 held by T2
T2 blocks on L3 held by T3
T4 blocks on L4 held by T4

Now we walk the chain

lock T1 -> lock L2 -> adjust L2 -> unlock T1 ->
     lock T2 ->  adjust T2 ->  drop locks

T2 times out and blocks on L0

Now we continue:

lock T2 -> lock L0 -> deadlock detected, but it's not a deadlock at all.

Brad tried to work around that in the deadlock detection logic itself,
but the more I looked at it the less I liked it, because it's crystal
ball magic after the fact.

We actually can detect a chain change very simple:

lock T1 -> lock L2 -> adjust L2 -> unlock T1 -> lock T2 -> adjust T2 ->

     next_lock = T2->pi_blocked_on->lock;

drop locks

T2 times out and blocks on L0

Now we continue:

lock T2 ->

     if (next_lock != T2->pi_blocked_on->lock)
     	   return;

So if we detect that T2 is now blocked on a different lock we stop the
chain walk. That's also correct in the following scenario:

lock T1 -> lock L2 -> adjust L2 -> unlock T1 -> lock T2 -> adjust T2 ->

     next_lock = T2->pi_blocked_on->lock;

drop locks

T3 times out and drops L3
T2 acquires L3 and blocks on L4 now

Now we continue:

lock T2 ->

     if (next_lock != T2->pi_blocked_on->lock)
     	   return;

We don't have to follow up the chain at that point, because T2
propagated our priority up to T4 already.

[ Folded a cleanup patch from peterz ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Brad Mouring <bmouring@ni.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140605152801.930031935@linutronix.de
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-17 15:39:50 -07:00
..
debug kdb,vt_console: Fix missed data due to pager overruns 2012-10-21 09:27:59 -07:00
events perf: Fix race in removing an event 2014-06-11 12:04:11 -07:00
gcov
irq genirq: Sanitize spurious interrupt detection of threaded irqs 2014-06-30 20:01:33 -07:00
power PM / Hibernate: Hibernate/thaw fixes/improvements 2014-02-20 10:45:33 -08:00
sched sched: Fix hotplug vs. set_cpus_allowed_ptr() 2014-06-11 12:04:11 -07:00
time nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off 2014-06-26 15:10:29 -04:00
trace tracing: Remove ftrace_stop/start() from reading the trace file 2014-07-17 15:39:50 -07:00
.gitignore
acct.c Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-08 12:19:57 -08:00
async.c Fix a dead loop in async_synchronize_full() 2012-10-02 10:30:35 -07:00
audit.c audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE 2014-04-14 06:44:15 -07:00
audit.h audit: remove AUDIT_SETUP_CONTEXT as it isn't used 2012-01-17 16:16:57 -05:00
audit_tree.c kernel/audit_tree.c: tree will leak memory when failure occurs in audit_trim_trees() 2013-05-11 13:48:14 -07:00
audit_watch.c
auditfilter.c audit: allow interfield comparison in audit rules 2012-01-17 16:17:01 -05:00
auditsc.c auditsc: audit_krule mask accesses need bounds checking 2014-06-16 13:45:46 -07:00
backtracetest.c
bounds.c
capability.c Revert "capabitlies: ns_capable can use the cap helpers rather than lsm call" 2012-01-17 10:19:41 -08:00
cgroup.c cgroup: cgroup_subsys->fork() should be called after the task is added to css_set 2014-03-11 16:10:03 -07:00
cgroup_freezer.c cgroup: cgroup_subsys->fork() should be called after the task is added to css_set 2014-03-11 16:10:03 -07:00
compat.c compat: Fix RT signal mask corruption via sigprocmask 2012-05-10 08:58:33 -07:00
configs.c
cpu.c sched: Fix hotplug vs. set_cpus_allowed_ptr() 2014-06-11 12:04:11 -07:00
cpu_pm.c
cpuset.c cpuset,mempolicy: fix sleeping function called from invalid context 2014-07-17 15:39:49 -07:00
crash_dump.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
cred.c cred: copy_process() should clear child->replacement_session_keyring 2012-04-11 08:20:11 -07:00
delayacct.c
dma.c Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
elfcore.c
exec_domain.c
exit.c wait: fix reparent_leader() vs EXIT_DEAD->EXIT_ZOMBIE race 2014-04-26 17:13:20 -07:00
extable.c
fork.c tracing: Fix syscall_*regfunc() vs copy_process() race 2014-07-06 18:49:20 -07:00
freezer.c PM / Freezer: Remove references to TIF_FREEZE in comments 2012-03-04 23:08:54 +01:00
futex.c futex: Make lookup_pi_state more robust 2014-06-07 16:02:16 -07:00
futex_compat.c futex: Revert "futex: Mark get_robust_list as deprecated" 2013-02-28 06:59:01 -08:00
groups.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
hrtimer.c hrtimer: Set expiry time before switch_hrtimer_base() 2014-06-07 16:02:01 -07:00
hung_task.c hung_task: fix the broken rcu_lock_break() logic 2012-03-05 15:49:42 -08:00
irq_work.c irq_work: fix compile failure on tile from missing include 2012-04-13 13:15:16 -04:00
itimer.c itimer: Use printk_once instead of WARN_ONCE 2012-04-10 11:00:30 +02:00
jump_label.c static keys: Inline the static_key_enabled() function 2012-02-28 20:01:08 +01:00
kallsyms.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage 2012-03-23 13:18:57 +01:00
Kconfig.preempt locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage 2012-03-23 13:18:57 +01:00
kexec.c Merge branch 'akpm' (Andrew's patch-bomb) 2012-03-28 17:19:28 -07:00
kfifo.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
kmod.c usermodehelper: check subprocess_info->path != NULL 2013-05-19 10:54:50 -07:00
kprobes.c kprobes: return proper error code from register_kprobe() 2012-03-05 15:49:42 -08:00
ksysfs.c kernel: ksysfs.c is implicitly using stat.h 2011-10-31 09:20:13 -04:00
kthread.c kthread_worker: reimplement flush_kthread_work() to allow freeing the work item being executed 2012-10-02 10:30:40 -07:00
latencytop.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
lockdep.c lockdep: Add CPU-idle/offline warning to lockdep-RCU splat 2012-02-21 09:06:06 -08:00
lockdep_internals.h
lockdep_proc.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
lockdep_states.h
Makefile sysctl: Move the implementation into fs/proc/proc_sysctl.c 2012-01-24 16:37:54 -08:00
module.c ftrace/module: Hardcode ftrace_module_init() call into load_module() 2014-06-07 16:02:00 -07:00
mutex-debug.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mutex-debug.h
mutex.c sched/rt: Use schedule_preempt_disabled() 2012-03-01 10:28:03 +01:00
mutex.h
notifier.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
nsproxy.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
padata.c padata: Fix cpu hotplug 2012-03-29 19:52:46 +08:00
panic.c panic: fix a possible deadlock in panic() 2013-04-12 09:38:47 -07:00
params.c params: <level>_initcall-like kernel parameters 2012-03-26 12:50:51 +10:30
pid.c vfs: fix panic in __d_lookup() with high dentry hashtable counts 2012-02-13 20:45:38 -05:00
pid_namespace.c pidns: add reboot_pid_ns() to handle the reboot syscall 2012-03-28 17:14:36 -07:00
posix-cpu-timers.c posix-cpu-timers: Fix nanosleep task_struct leak 2013-02-28 06:58:59 -08:00
posix-timers.c posix-timer: Don't call idr_find() with out-of-range ID 2013-03-04 06:06:38 +08:00
printk.c printk: Fix rq->lock vs logbuf_lock unlock lock inversion 2014-04-14 06:44:16 -07:00
profile.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
ptrace.c exec/ptrace: fix get_dumpable() incorrect tests 2013-11-29 10:50:34 -08:00
range.c range: fix bogus misuse of module.h to get printk() 2011-10-31 09:20:11 -04:00
rcu.h rcu: Allow nesting of rcu_idle_enter() and rcu_idle_exit() 2012-02-21 09:06:12 -08:00
rcupdate.c rcu: Check for illegal use of RCU from offlined CPUs 2012-02-21 09:06:03 -08:00
rcutiny.c rcu: Add RCU_NONIDLE() for idle-loop RCU read-side critical sections 2012-02-21 09:06:13 -08:00
rcutiny_plugin.h rcu: Simplify unboosting checks 2012-02-21 09:03:43 -08:00
rcutorture.c PTR_ERR should be called before its argument is cleared. 2012-02-21 09:06:10 -08:00
rcutree.c rcu: Fix batch-limit size problem 2012-12-17 10:37:46 -08:00
rcutree.h rcu: Rework detection of use of RCU by offline CPUs 2012-02-21 09:06:07 -08:00
rcutree_plugin.h rcu: Hold off RCU_FAST_NO_HZ after timer posted 2012-02-21 09:42:30 -08:00
rcutree_trace.c rcu: Rework detection of use of RCU by offline CPUs 2012-02-21 09:06:07 -08:00
relay.c splice: fix racy pipe->buffers uses 2012-07-16 09:04:42 -07:00
res_counter.c net: introduce res_counter_charge_nofail() for socket allocations 2012-01-22 15:08:46 -05:00
resource.c kernel/resource.c: fix stack overflow in __reserve_region_with_split() 2013-02-14 10:48:53 -08:00
rtmutex-debug.c lockdep, rtmutex, bug: Show taint flags on error 2011-12-06 08:16:49 +01:00
rtmutex-debug.h
rtmutex-tester.c rtmutex-tester: convert sysdev_class to a regular subsystem 2011-12-14 14:54:22 -08:00
rtmutex.c rtmutex: Detect changes in the pi lock chain 2014-07-17 15:39:50 -07:00
rtmutex.h
rtmutex_common.h
rwsem.c Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
seccomp.c seccomp: audit abnormal end to a process due to seccomp 2012-01-17 16:16:55 -05:00
semaphore.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
signal.c kernel/signal.c: stop info leak via the tkill and the tgkill syscalls 2013-04-25 21:19:54 -07:00
smp.c smp: Fix SMP function call empty cpu mask race 2013-02-03 18:24:42 -06:00
softirq.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-20 10:32:09 -07:00
spinlock.c locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage 2012-03-23 13:18:57 +01:00
srcu.c rcu: Call out dangers of expedited RCU primitives 2012-02-21 09:06:08 -08:00
stacktrace.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
stop_machine.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
sys.c reboot: rigrate shutdown/reboot to boot cpu 2013-06-20 11:58:45 -07:00
sys_ni.c Cross Memory Attach 2011-10-31 17:30:44 -07:00
sysctl.c hung_task: check the value of "sysctl_hung_task_timeout_sec" 2014-05-06 07:51:45 -07:00
sysctl_binary.c sysctl: fix null checking in bin_dn_node_address() 2013-03-04 06:06:41 +08:00
taskstats.c
test_kprobes.c
time.c time: Remove bogus comments 2012-03-15 18:17:55 -07:00
timeconst.pl timeconst.pl: Eliminate Perl warning 2013-02-28 06:58:58 -08:00
timer.c timer: Prevent overflow in apply_slack 2014-06-07 16:02:00 -07:00
tracepoint.c tracepoint: Do not waste memory on mods with no tracepoints 2014-05-18 05:25:56 -07:00
tsacct.c [S390] cputime: add sparse checking and cleanup 2011-12-15 14:56:19 +01:00
uid16.c
up.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user-return-notifier.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
user_namespace.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
utsname.c kernel: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
utsname_sysctl.c Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux 2011-11-06 19:44:47 -08:00
wait.c lockdep/waitqueues: Add better annotation 2011-12-21 10:07:39 +01:00
watchdog.c watchdog: using u64 in get_sample_period() 2012-12-03 11:47:17 -08:00
workqueue.c workqueue: cond_resched() after processing each work item 2014-04-14 06:44:16 -07:00
workqueue_sched.h