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2002-05-02 Robert Collins <rbtcollins@hotmail.com>

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* thread.cc (__pthread_cond_dowait): Fix a race on signalling from a
        thread woken by the same condition variable it's signalling on. Thanks
        to Michael Beach for the report and test case.
This commit is contained in:
Robert Collins 2002-05-02 11:26:22 +00:00
parent 4c956a7c0f
commit 37143995da
2 changed files with 14 additions and 5 deletions
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7
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,9 @@
2002-05-02 Robert Collins <rbtcollins@hotmail.com>
* thread.cc (__pthread_cond_dowait): Fix a race on signalling from a
thread woken by the same condition variable it's signalling on. Thanks
to Michael Beach for the report and test case.
2002-05-02 Christopher Faylor <cgf@redhat.com> 2002-05-02 Christopher Faylor <cgf@redhat.com>
* path.h (pathconv_arg): Add PC_POSIX. * path.h (pathconv_arg): Add PC_POSIX.
@ -44,6 +50,7 @@ Wed May 1 16:06:02 2002 Jason Tishler <jason@tishler.net>
* include/cygwin/types.h: Include <sys/sysmacros.h>. * include/cygwin/types.h: Include <sys/sysmacros.h>.
>>>>>>> 1.1179
Wed Apr 17 11:27:04 2002 Jason Tishler <jason@tishler.net> Wed Apr 17 11:27:04 2002 Jason Tishler <jason@tishler.net>
* security.cc (get_lsa_srv_inf): Prevent extraneous backslashes for * security.cc (get_lsa_srv_inf): Prevent extraneous backslashes for

12
winsup/cygwin/thread.cc
View File

@ -1791,20 +1791,22 @@ __pthread_cond_dowait (pthread_cond_t *cond, pthread_mutex_t *mutex,
InterlockedIncrement (&((*themutex)->condwaits)); InterlockedIncrement (&((*themutex)->condwaits));
if (pthread_mutex_unlock (&(*cond)->cond_access)) if (pthread_mutex_unlock (&(*cond)->cond_access))
system_printf ("Failed to unlock condition variable access mutex, this %p", *cond); system_printf ("Failed to unlock condition variable access mutex, this %p", *cond);
/* At this point calls to Signal will progress evebn if we aren' yet waiting
* However, the loop there should allow us to get scheduled and call wait,
* and have them call PulseEvent again if we dont' respond.
*/
rv = (*cond)->TimedWait (waitlength); rv = (*cond)->TimedWait (waitlength);
/* this may allow a race on the mutex acquisition and waits.. /* this may allow a race on the mutex acquisition and waits..
* But doing this within the cond access mutex creates a different race * But doing this within the cond access mutex creates a different race
*/ */
bool last = false; InterlockedDecrement (&((*cond)->waiting));
if (InterlockedDecrement (&((*cond)->waiting)) == 0)
last = true;
/* Tell Signal that we have been released */ /* Tell Signal that we have been released */
InterlockedDecrement (&((*cond)->ExitingWait)); InterlockedDecrement (&((*cond)->ExitingWait));
(*themutex)->Lock (); (*themutex)->Lock ();
if (last == true)
(*cond)->mutex = NULL;
if (pthread_mutex_lock (&(*cond)->cond_access)) if (pthread_mutex_lock (&(*cond)->cond_access))
system_printf ("Failed to lock condition variable access mutex, this %p", *cond); system_printf ("Failed to lock condition variable access mutex, this %p", *cond);
if ((*cond)->waiting == 0)
(*cond)->mutex = NULL;
InterlockedDecrement (&((*themutex)->condwaits)); InterlockedDecrement (&((*themutex)->condwaits));
if (pthread_mutex_unlock (&(*cond)->cond_access)) if (pthread_mutex_unlock (&(*cond)->cond_access))
system_printf ("Failed to unlock condition variable access mutex, this %p", *cond); system_printf ("Failed to unlock condition variable access mutex, this %p", *cond);