rpm/rpm-4.4.2-rpmsq-deadlock.patch

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2006-01-31 16:20:31 +00:00
--- rpm-4.4.2/rpmio/rpmsq.c.deadlock 2005-07-13 06:47:03.000000000 -0400
+++ rpm-4.4.2/rpmio/rpmsq.c 2006-01-30 21:00:13.000000000 -0500
@@ -218,7 +218,6 @@
sq->id = ME();
ret = pthread_mutex_init(&sq->mutex, NULL);
- ret = pthread_cond_init(&sq->cond, NULL);
insque(elem, (prev != NULL ? prev : rpmsqQueue));
ret = sigrelse(SIGCHLD);
}
@@ -240,8 +239,11 @@
ret = sighold (SIGCHLD);
if (ret == 0) {
remque(elem);
- ret = pthread_cond_destroy(&sq->cond);
- ret = pthread_mutex_destroy(&sq->mutex);
+
+ /* Unlock the mutex and then destroy it */
+ if((ret = pthread_mutex_unlock(&sq->mutex)) == 0)
+ ret = pthread_mutex_destroy(&sq->mutex);
+
sq->id = NULL;
/*@-bounds@*/
if (sq->pipes[1]) ret = close(sq->pipes[1]);
@@ -315,11 +317,20 @@
sq != NULL && sq != rpmsqQueue;
sq = sq->q_forw)
{
+ int ret;
+
if (sq->child != reaped)
/*@innercontinue@*/ continue;
sq->reaped = reaped;
sq->status = status;
- (void) pthread_cond_signal(&sq->cond);
+
+ /* Unlock the mutex. The waiter will then be able to
+ * aquire the lock.
+ *
+ * XXX: jbj, wtd, if this fails?
+ */
+ ret = pthread_mutex_unlock(&sq->mutex);
+
/*@innerbreak@*/ break;
}
}
@@ -391,6 +402,7 @@
{
pid_t pid;
int xx;
+ int nothreads = 0; /* XXX: Shouldn't this be a global? */
if (sq->reaper) {
xx = rpmsqInsert(sq, NULL);
@@ -405,6 +417,24 @@
xx = sighold(SIGCHLD);
+ /*
+ * Initialize the cond var mutex. We have to aquire the lock we
+ * use for the condition before we fork. Otherwise it is possible for
+ * the child to exit, we get sigchild and the sig handler to send
+ * the condition signal before we are waiting on the condition.
+ */
+ if (!nothreads) {
+ if(pthread_mutex_lock(&sq->mutex)) {
+ /* Yack we did not get the lock, lets just give up */
+/*@-bounds@*/
+ xx = close(sq->pipes[0]);
+ xx = close(sq->pipes[1]);
+ sq->pipes[0] = sq->pipes[1] = -1;
+/*@=bounds@*/
+ goto out;
+ }
+ }
+
pid = fork();
if (pid < (pid_t) 0) { /* fork failed. */
/*@-bounds@*/
@@ -462,10 +492,6 @@
/* Protect sq->reaped from handler changes. */
ret = sighold(SIGCHLD);
- /* Initialize the cond var mutex. */
- if (!nothreads)
- ret = pthread_mutex_lock(&sq->mutex);
-
/* Start the child, linux often runs child before parent. */
/*@-bounds@*/
if (sq->pipes[0] >= 0)
@@ -486,7 +512,13 @@
ret = sigpause(SIGCHLD);
else {
xx = sigrelse(SIGCHLD);
- ret = pthread_cond_wait(&sq->cond, &sq->mutex);
+
+ /*
+ * We start before the fork with this mutex locked;
+ * The only one that unlocks this the signal handler.
+ * So if we get the lock the child has been reaped.
+ */
+ ret = pthread_mutex_lock(&sq->mutex);
xx = sighold(SIGCHLD);
}
}
@@ -495,9 +527,6 @@
/* Accumulate stopwatch time spent waiting, potential performance gain. */
sq->ms_scriptlets += rpmswExit(&sq->op, -1)/1000;
- /* Tear down cond var mutex, our child has been reaped. */
- if (!nothreads)
- xx = pthread_mutex_unlock(&sq->mutex);
xx = sigrelse(SIGCHLD);
#ifdef _RPMSQ_DEBUG