[PING][PATCH] Fix race in pthread_mutex_lock while promoting to PTHREAD_MUTEX_ELISION_NP [BZ #23275]

[Stefan Liebler]

PING

On 06/26/2018 08:45 AM, Stefan Liebler wrote:
> PING
> 
> On 06/19/2018 09:45 AM, Stefan Liebler wrote:
>> PING
>>
>> On 06/12/2018 04:24 PM, Stefan Liebler wrote:
>>> Hi,
>>>
>>> The race leads either to pthread_mutex_destroy returning EBUSY or 
>>> triggering an assertion (See description in bugzilla).
>>>
>>> This patch is fixing the race by ensuring that the elision path is 
>>> used in all cases if elision is enabled by the GLIBC_TUNABLES framework.
>>>
>>> The __kind variable in struct __pthread_mutex_s is accessed 
>>> concurrently. Therefore we are now using the atomic macros.
>>>
>>> The new testcase tst-mutex10 is triggering the race on s390x and 
>>> intel. Presumably also on power, but I don't have access to a power 
>>> machine with lock-elision. At least the code for power is the same as 
>>> on the other two architectures. Can somebody test it on power?
>>>
>>> Bye
>>> Stefan
>>>
>>> ChangeLog:
>>>
>>> Â Â Â Â Â [BZ #23275]
>>> Â Â Â Â Â * nptl/tst-mutex10.c: New File.
>>> Â Â Â Â Â * nptl/Makefile (tests): Add tst-mutex10.
>>> Â Â Â Â Â (tst-mutex-ENV): New variable.
>>> Â Â Â Â Â * sysdeps/unix/sysv/linux/s390/force-elision.h: (FORCE_ELISION):
>>> Â Â Â Â Â Ensure that elision path is used if elision is available.
>>> Â Â Â Â Â * sysdeps/unix/sysv/linux/powerpc/force-elision.h
>>> Â Â Â Â Â (FORCE_ELISION): Likewise.
>>> Â Â Â Â Â * sysdeps/unix/sysv/linux/x86/force-elision.h: (FORCE_ELISION):
>>> Â Â Â Â Â Likewise.
>>> Â Â Â Â Â * nptl/pthreadP.h (PTHREAD_MUTEX_TYPE,
>>> Â Â Â Â Â PTHREAD_MUTEX_TYPE_ELISION, PTHREAD_MUTEX_PSHARED):
>>> Â Â Â Â Â Use atomic_load_relaxed.
>>> Â Â Â Â Â * nptl/pthread_mutex_consistent.c (pthread_mutex_consistent):
>>> Â Â Â Â Â Likewise.
>>> Â Â Â Â Â * nptl/pthread_mutex_getprioceiling.c
>>> Â Â Â Â Â (pthread_mutex_getprioceiling): Likewise.
>>> Â Â Â Â Â * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full,
>>> Â Â Â Â Â __pthread_mutex_cond_lock_adjust): Likewise.
>>> Â Â Â Â Â * nptl/pthread_mutex_setprioceiling.c
>>> Â Â Â Â Â (pthread_mutex_setprioceiling): Likewise.
>>> Â Â Â Â Â * nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock):
>>> Â Â Â Â Â Likewise.
>>> Â Â Â Â Â * nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock):
>>> Â Â Â Â Â Likewise.
>>> Â Â Â Â Â * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full):
>>> Â Â Â Â Â Likewise.
>>> Â Â Â Â Â * sysdeps/nptl/bits/thread-shared-types.h
>>> Â Â Â Â Â (struct __pthread_mutex_s): Add comments.
>>> Â Â Â Â Â * nptl/pthread_mutex_destroy.c (__pthread_mutex_destroy):
>>> Â Â Â Â Â Use atomic_load_relaxed and atomic_store_relaxed.
>>> Â Â Â Â Â * nptl/pthread_mutex_init.c (__pthread_mutex_init):
>>> Â Â Â Â Â Use atomic_store_relaxed.
>>
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