diff options
| author | Leonid Lisovskiy <lly.dev@gmail.com> | 2016-05-29 10:06:55 +0300 |
|---|---|---|
| committer | Waldemar Brodkorb <wbx@uclibc-ng.org> | 2016-05-31 21:00:13 +0200 |
| commit | 361f679c652647cdea4d5a66999a4b96c1653576 (patch) | |
| tree | 3c647ca4d3594e0598bc7d624a2f8ccf8ddbbfa0 /libpthread/linuxthreads | |
| parent | 8b28fc50a3891f823531aa276008e1b1b17e0a79 (diff) | |
linuxthreads.old: Fix segfault when pthread_mutex_unlock() called against unlocked NORMAL mutex.
Althought, it is undefined behavior, there is no reason for segfault.
Program received signal SIGSEGV, Segmentation fault.
__pthread_unlock (lock=lock@entry=0x804b03c <lock+16>)
at libpthread/linuxthreads.old/spinlock.c:231
231 (&lock->__status, oldstatus, (long)(thr->p_nextlock) & ~1L))
It occurs only on platforms which has HAS_COMPARE_AND_SWAP defined.
Restore glibc commit fbaf6e72d6 "spinlock.c (__pthread_unlock): Don't crash if
called for an untaken mutex." behavior, broken later by commit 4ad1d0cfbf.
Signed-off-by: Leonid Lisovskiy <lly.dev@gmail.com>
Diffstat (limited to 'libpthread/linuxthreads')
| -rw-r--r-- | libpthread/linuxthreads/spinlock.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/libpthread/linuxthreads/spinlock.c b/libpthread/linuxthreads/spinlock.c index 80aeda529..ce970029e 100644 --- a/libpthread/linuxthreads/spinlock.c +++ b/libpthread/linuxthreads/spinlock.c @@ -188,10 +188,16 @@ int __pthread_unlock(struct _pthread_fastlock * lock) WRITE_MEMORY_BARRIER(); again: - while ((oldstatus = lock->__status) == 1) { - if (__compare_and_swap_with_release_semantics(&lock->__status, + oldstatus = lock->__status; + if (oldstatus == 0 || oldstatus == 1) { + /* No threads are waiting for this lock. Please note that we also + enter this case if the lock is not taken at all. If this wouldn't + be done here we would crash further down. */ + if (! __compare_and_swap_with_release_semantics(&lock->__status, oldstatus, 0)) - return 0; + goto again; + + return 0; } /* Find thread in waiting queue with maximal priority */ |