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authorTulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>2016-10-28 18:31:24 -0200
committerTulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>2016-10-28 19:13:21 -0200
commit739e14f9009ff91e4a8d01776e7269fc8cbd0293 (patch)
treeb8819e16088ba37dcc26c7cfa7f1ae486b7e474f /nptl
parentce193f551ec21df85c934626a21730881484dcf0 (diff)
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Document a behavior of an elided pthread_rwlock_unlock
Explain that pthread_rwlock_unlock may crash if called on a lock not
held by the current thread.
Diffstat (limited to 'nptl')
-rw-r--r--nptl/pthread_rwlock_unlock.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/nptl/pthread_rwlock_unlock.c b/nptl/pthread_rwlock_unlock.c
index a6cadd491d..112f748a6b 100644
--- a/nptl/pthread_rwlock_unlock.c
+++ b/nptl/pthread_rwlock_unlock.c
@@ -35,6 +35,10 @@ __pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
 
   LIBC_PROBE (rwlock_unlock, 1, rwlock);
 
+  /* Trying to elide an unlocked lock may crash the process.  This
+     is expected and is compatible with POSIX.1-2008: "results are
+     undefined if the read-write lock rwlock is not held by the
+     calling thread".  */
   if (ELIDE_UNLOCK (rwlock->__data.__writer == 0
 		    && rwlock->__data.__nr_readers == 0))
     return 0;