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

[Stefan Liebler <stli at linux dot ibm dot com>]

PING
On 07/23/2018 08:42 AM, Stefan Liebler wrote:
> PING
> Please have a look at the patch posted here:
> https://www.sourceware.org/ml/libc-alpha/2018-06/msg00246.html
>
> On 07/16/2018 01:56 PM, Stefan Liebler wrote:
> > PING
> >
> > On 07/10/2018 08:33 AM, Stefan Liebler wrote:
> > > 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.