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authorUlrich Drepper <drepper@redhat.com>2006-08-13 01:56:09 +0000
committerUlrich Drepper <drepper@redhat.com>2006-08-13 01:56:09 +0000
commit22bb134c318365dbac664e46c193538c14bf3c42 (patch)
tree6ec10e5142ec9266baf7c0cca31bf7e766804263 /nptl/pthread_join.c
parent4c3f81d07ae921bb58def1f34c8758a77989b219 (diff)
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[BZ #2843]
2006-08-12 Ulrich Drepper <drepper@redhat.com> [BZ #2843] * pthread_join.c (pthread_join): Account for self being canceled when checking for deadlocks. * tst-join5.c: Cleanups. Allow to be used in tst-join6. (tf1): Don't print anything after pthread_join returns, this would be another cancellation point. (tf2): Likewise. * tst-join6.c: New file. * Makefile (tests): Add tst-join6.
Diffstat (limited to 'nptl/pthread_join.c')
-rw-r--r--nptl/pthread_join.c78
1 files changed, 42 insertions, 36 deletions
diff --git a/nptl/pthread_join.c b/nptl/pthread_join.c
index 70dc81a..c88d85b 100644
--- a/nptl/pthread_join.c
+++ b/nptl/pthread_join.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002, 2003, 2005 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003, 2005, 2006 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
@@ -27,7 +27,11 @@
static void
cleanup (void *arg)
{
- *(void **) arg = NULL;
+ /* If we already changed the waiter ID, reset it. The call cannot
+ fail for any reason but the thread not having done that yet so
+ there is no reason for a loop. */
+ atomic_compare_and_exchange_bool_acq ((struct pthread **) arg, NULL,
+ THREAD_SELF);
}
@@ -36,7 +40,6 @@ pthread_join (threadid, thread_return)
pthread_t threadid;
void **thread_return;
{
- struct pthread *self;
struct pthread *pd = (struct pthread *) threadid;
/* Make sure the descriptor is valid. */
@@ -49,12 +52,23 @@ pthread_join (threadid, thread_return)
/* We cannot wait for the thread. */
return EINVAL;
- self = THREAD_SELF;
- if (pd == self
- || (self->joinid == pd
- && (pd->cancelhandling
- & (CANCELING_BITMASK | CANCELED_BITMASK | EXITING_BITMASK
- | TERMINATED_BITMASK)) == 0))
+ struct pthread *self = THREAD_SELF;
+ int result = 0;
+
+ /* During the wait we change to asynchronous cancellation. If we
+ are canceled the thread we are waiting for must be marked as
+ un-wait-ed for again. */
+ pthread_cleanup_push (cleanup, &pd->joinid);
+
+ /* Switch to asynchronous cancellation. */
+ int oldtype = CANCEL_ASYNC ();
+
+ if ((pd == self
+ || (self->joinid == pd
+ && (pd->cancelhandling
+ & (CANCELING_BITMASK | CANCELED_BITMASK | EXITING_BITMASK
+ | TERMINATED_BITMASK)) == 0))
+ && !CANCEL_ENABLED_AND_CANCELED (self->cancelhandling))
/* This is a deadlock situation. The threads are waiting for each
other to finish. Note that this is a "may" error. To be 100%
sure we catch this error we would have to lock the data
@@ -62,28 +76,17 @@ pthread_join (threadid, thread_return)
two threads are really caught in this situation they will
deadlock. It is the programmer's problem to figure this
out. */
- return EDEADLK;
-
+ result = EDEADLK;
/* Wait for the thread to finish. If it is already locked something
is wrong. There can only be one waiter. */
- if (__builtin_expect (atomic_compare_and_exchange_bool_acq (&pd->joinid,
- self,
- NULL), 0))
+ else if (__builtin_expect (atomic_compare_and_exchange_bool_acq (&pd->joinid,
+ self,
+ NULL), 0))
/* There is already somebody waiting for the thread. */
- return EINVAL;
-
-
- /* During the wait we change to asynchronous cancellation. If we
- are cancelled the thread we are waiting for must be marked as
- un-wait-ed for again. */
- pthread_cleanup_push (cleanup, &pd->joinid);
-
- /* Switch to asynchronous cancellation. */
- int oldtype = CANCEL_ASYNC ();
-
-
- /* Wait for the child. */
- lll_wait_tid (pd->tid);
+ result = EINVAL;
+ else
+ /* Wait for the child. */
+ lll_wait_tid (pd->tid);
/* Restore cancellation mode. */
@@ -93,16 +96,19 @@ pthread_join (threadid, thread_return)
pthread_cleanup_pop (0);
- /* We mark the thread as terminated and as joined. */
- pd->tid = -1;
+ if (__builtin_expect (result == 0, 1))
+ {
+ /* We mark the thread as terminated and as joined. */
+ pd->tid = -1;
- /* Store the return value if the caller is interested. */
- if (thread_return != NULL)
- *thread_return = pd->result;
+ /* Store the return value if the caller is interested. */
+ if (thread_return != NULL)
+ *thread_return = pd->result;
- /* Free the TCB. */
- __free_tcb (pd);
+ /* Free the TCB. */
+ __free_tcb (pd);
+ }
- return 0;
+ return result;
}