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Fix a race in pthread_rwlock caused by simultanoues unlock and cancelation.

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* thread.h (pthread_rwlock::release): New method.
* thread.cc (pthread_rwlock::unlock): Use release to signal
waiting threads.
(pthread_rwlock::rdlock_cleanup): Signal waiting threads after a
cancelation.
(pthread_rwlock::wrlock_cleanup): Ditto.
This commit is contained in:
Thomas Pfaff 2003-04-15 20:14:12 +00:00
parent cfd2c7bea8
commit ffb576fbf2
3 changed files with 24 additions and 7 deletions
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9
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,12 @@
2003-04-15 Thomas Pfaff <tpfaff@gmx.net>
* thread.h (pthread_rwlock::release): New method.
* thread.cc (pthread_rwlock::unlock): Use release to signal
waiting threads.
(pthread_rwlock::rdlock_cleanup): Signal waiting threads after a
cancelation.
(pthread_rwlock::wrlock_cleanup): Ditto.
2003-04-13 Pierre Humblet <pierre.humblet@ieee.org> 2003-04-13 Pierre Humblet <pierre.humblet@ieee.org>
* mkvers.sh: Prefix day with 0 in date only when day < 10. * mkvers.sh: Prefix day with 0 in date only when day < 10.

10
winsup/cygwin/thread.cc
View File

@ -1210,13 +1210,7 @@ pthread_rwlock::unlock ()
delete reader; delete reader;
} }
if (waiting_writers) release ();
{
if (!readers)
cond_writers.unblock (false);
}
else if (waiting_readers)
cond_readers.unblock (true);
DONE: DONE:
mtx.unlock (); mtx.unlock ();
@ -1263,6 +1257,7 @@ pthread_rwlock::rdlock_cleanup (void *arg)
pthread_rwlock *rwlock = (pthread_rwlock *) arg; pthread_rwlock *rwlock = (pthread_rwlock *) arg;
--(rwlock->waiting_readers); --(rwlock->waiting_readers);
rwlock->release ();
rwlock->mtx.unlock (); rwlock->mtx.unlock ();
} }
@ -1272,6 +1267,7 @@ pthread_rwlock::wrlock_cleanup (void *arg)
pthread_rwlock *rwlock = (pthread_rwlock *) arg; pthread_rwlock *rwlock = (pthread_rwlock *) arg;
--(rwlock->waiting_writers); --(rwlock->waiting_writers);
rwlock->release ();
rwlock->mtx.unlock (); rwlock->mtx.unlock ();
} }

12
winsup/cygwin/thread.h
View File

@ -587,6 +587,18 @@ private:
void remove_reader (struct RWLOCK_READER *rd); void remove_reader (struct RWLOCK_READER *rd);
struct RWLOCK_READER *lookup_reader (pthread_t thread); struct RWLOCK_READER *lookup_reader (pthread_t thread);
void release ()
{
if (waiting_writers)
{
if (!readers)
cond_writers.unblock (false);
}
else if (waiting_readers)
cond_readers.unblock (true);
}
static void rdlock_cleanup (void *arg); static void rdlock_cleanup (void *arg);
static void wrlock_cleanup (void *arg); static void wrlock_cleanup (void *arg);