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BUG#24507 (rpl_log.test crash slave):

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The problem was located to lie inside current NPTL pthread_exit() 
implementation. Race conditions in this code can lead to segmentation
fault. Hovewer, this can happen only in a race between first thread 
calling pthread_exit() and other threads. 

Workaround implemented in this patch spawns a dummy thread, which
exits immediately, during thread lib initialization. This will exclude
segment violations when further threads exit.
This commit is contained in:
rafal@quant.(none)
2006-12-08 11:41:12 +01:00
parent 3406fcea39
commit 5d7af856f7
2 changed files with 59 additions and 0 deletions
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20
include/my_pthread.h
View File

@ -31,6 +31,26 @@ extern "C" {
#define EXTERNC #define EXTERNC
#endif /* __cplusplus */ #endif /* __cplusplus */
/*
BUG#24507: Race conditions inside current NPTL pthread_exit() implementation.
If macro NPTL_PTHREAD_EXIT_HACK is defined then a hack described in the bug
report will be implemented inside my_thread_global_init() in my_thr_init.c.
This amounts to spawning a dummy thread which does nothing but executes
pthread_exit(0).
This bug is fixed in version 2.5 of glibc library.
TODO: Remove this code when fixed versions of glibc6 are in common use.
*/
#if defined(TARGET_OS_LINUX) && defined(HAVE_NPTL) &&
defined(__GLIBC__) && ( __GLIBC__ < 2 || __GLIBC__ == 2 && __GLIBC_MINOR__ < 5 )
#define NPTL_PTHREAD_EXIT_BUG 1
#endif
#if defined(__WIN__) || defined(OS2) #if defined(__WIN__) || defined(OS2)
#ifdef OS2 #ifdef OS2

39
mysys/my_thr_init.c
View File

@ -44,6 +44,23 @@ pthread_mutexattr_t my_fast_mutexattr;
pthread_mutexattr_t my_errorcheck_mutexattr; pthread_mutexattr_t my_errorcheck_mutexattr;
#endif #endif
#ifdef NPTL_PTHREAD_EXIT_BUG /* see my_pthread.h */
/*
Dummy thread spawned in my_thread_global_init() below to avoid
race conditions in NPTL pthread_exit code.
*/
static
pthread_handler_t nptl_pthread_exit_hack_handler(void *arg)
{
/* Do nothing! */
pthread_exit(0);
return 0;
}
#endif
/* /*
initialize thread environment initialize thread environment
@ -63,6 +80,28 @@ my_bool my_thread_global_init(void)
return 1; return 1;
} }
#ifdef NPTL_PTHREAD_EXIT_BUG
/*
BUG#24507: Race conditions inside current NPTL pthread_exit() implementation.
To avoid a possible segmentation fault during concurrent executions of
pthread_exit(), a dummy thread is spawned which initializes internal variables
of pthread lib. See bug description for thoroughfull explanation.
TODO: Remove this code when fixed versions of glibc6 are in common use.
*/
pthread_t dummy_thread;
pthread_attr_t dummy_thread_attr;
pthread_attr_init(&dummy_thread_attr);
pthread_attr_setdetachstate(&dummy_thread_attr,PTHREAD_CREATE_DETACHED);
pthread_create(&dummy_thread,&dummy_thread_attr,nptl_pthread_exit_hack_handler,NULL);
#endif
#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP #ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
/* /*
Set mutex type to "fast" a.k.a "adaptive" Set mutex type to "fast" a.k.a "adaptive"