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

[Stefan Liebler <stli@linux.ibm.com>]

PING

On 07/03/2018 08:28 AM, Stefan Liebler wrote:
> 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:
>>>>
>>>>      [BZ #23275]
>>>>      * nptl/tst-mutex10.c: New File.
>>>>      * nptl/Makefile (tests): Add tst-mutex10.
>>>>      (tst-mutex-ENV): New variable.
>>>>      * sysdeps/unix/sysv/linux/s390/force-elision.h: (FORCE_ELISION):
>>>>      Ensure that elision path is used if elision is available.
>>>>      * sysdeps/unix/sysv/linux/powerpc/force-elision.h
>>>>      (FORCE_ELISION): Likewise.
>>>>      * sysdeps/unix/sysv/linux/x86/force-elision.h: (FORCE_ELISION):
>>>>      Likewise.
>>>>      * nptl/pthreadP.h (PTHREAD_MUTEX_TYPE,
>>>>      PTHREAD_MUTEX_TYPE_ELISION, PTHREAD_MUTEX_PSHARED):
>>>>      Use atomic_load_relaxed.
>>>>      * nptl/pthread_mutex_consistent.c (pthread_mutex_consistent):
>>>>      Likewise.
>>>>      * nptl/pthread_mutex_getprioceiling.c
>>>>      (pthread_mutex_getprioceiling): Likewise.
>>>>      * nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full,
>>>>      __pthread_mutex_cond_lock_adjust): Likewise.
>>>>      * nptl/pthread_mutex_setprioceiling.c
>>>>      (pthread_mutex_setprioceiling): Likewise.
>>>>      * nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock):
>>>>      Likewise.
>>>>      * nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock):
>>>>      Likewise.
>>>>      * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full):
>>>>      Likewise.
>>>>      * sysdeps/nptl/bits/thread-shared-types.h
>>>>      (struct __pthread_mutex_s): Add comments.
>>>>      * nptl/pthread_mutex_destroy.c (__pthread_mutex_destroy):
>>>>      Use atomic_load_relaxed and atomic_store_relaxed.
>>>>      * nptl/pthread_mutex_init.c (__pthread_mutex_init):
>>>>      Use atomic_store_relaxed.
>>>
>>
>