SOURCES: rpm-bug-146549.patch (NEW) - lockup fix

[glen]

Author: glen                         Date: Wed Apr 26 22:04:59 2006 GMT
Module: SOURCES                       Tag: HEAD
---- Log message:
- lockup fix

---- Files affected:
SOURCES:
   rpm-bug-146549.patch (NONE -> 1.1)  (NEW)

---- Diffs:

================================================================
Index: SOURCES/rpm-bug-146549.patch
diff -u /dev/null SOURCES/rpm-bug-146549.patch:1.1
--- /dev/null	Thu Apr 27 00:04:59 2006
+++ SOURCES/rpm-bug-146549.patch	Thu Apr 27 00:04:54 2006
@@ -0,0 +1,117 @@
+https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=146549
+
+--- rpm-4.4.2/rpmio/rpmsq.c.deadlock	2005-07-13 12:47:03.000000000 +0200
++++ rpm-4.4.2/rpmio/rpmsq.c	2005-08-19 14:47:53.000000000 +0200
+@@ -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
================================================================