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Occasionally, the alertpipe loses its nonblocking status, so detect and correct

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that situation before it causes a deadlock.  (Reported and tested by ctooley
via #asterisk-dev)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@122130 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Tilghman Lesher
2008-06-12 15:11:30 +00:00
parent 50449140e8
commit 4767c11e8b
1 changed files with 26 additions and 3 deletions
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29
main/channel.c
View File

@@ -758,6 +758,7 @@ struct ast_channel *ast_channel_alloc(int needqueue, int state, const char *cid_
if (needqueue) {
if (pipe(tmp->alertpipe)) {
ast_log(LOG_WARNING, "Channel allocation failed: Can't create alert pipe!\n");
alertpipe_failed:
#ifdef HAVE_ZAPTEL
if (tmp->timingfd > -1)
close(tmp->timingfd);
@@ -768,9 +769,19 @@ struct ast_channel *ast_channel_alloc(int needqueue, int state, const char *cid_
return NULL;
} else {
flags = fcntl(tmp->alertpipe[0], F_GETFL);
fcntl(tmp->alertpipe[0], F_SETFL, flags | O_NONBLOCK);
if (fcntl(tmp->alertpipe[0], F_SETFL, flags | O_NONBLOCK) < 0) {
ast_log(LOG_WARNING, "Channel allocation failed: Unable to set alertpipe nonblocking! (%d: %s)\n", errno, strerror(errno));
close(tmp->alertpipe[0]);
close(tmp->alertpipe[1]);
goto alertpipe_failed;
}
flags = fcntl(tmp->alertpipe[1], F_GETFL);
fcntl(tmp->alertpipe[1], F_SETFL, flags | O_NONBLOCK);
if (fcntl(tmp->alertpipe[1], F_SETFL, flags | O_NONBLOCK) < 0) {
ast_log(LOG_WARNING, "Channel allocation failed: Unable to set alertpipe nonblocking! (%d: %s)\n", errno, strerror(errno));
close(tmp->alertpipe[0]);
close(tmp->alertpipe[1]);
goto alertpipe_failed;
}
}
} else /* Make sure we've got it done right if they don't */
tmp->alertpipe[0] = tmp->alertpipe[1] = -1;
@@ -1994,8 +2005,20 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
/* Read and ignore anything on the alertpipe, but read only
one sizeof(blah) per frame that we send from it */
if (chan->alertpipe[0] > -1)
if (chan->alertpipe[0] > -1) {
int flags = fcntl(chan->alertpipe[0], F_GETFL);
/* For some odd reason, the alertpipe occasionally loses nonblocking status,
* which immediately causes a deadlock scenario. Detect and prevent this. */
if ((flags & O_NONBLOCK) == 0) {
ast_log(LOG_ERROR, "Alertpipe on channel %s lost O_NONBLOCK?!!\n", chan->name);
if (fcntl(chan->alertpipe[0], F_SETFL, flags | O_NONBLOCK) < 0) {
ast_log(LOG_WARNING, "Unable to set alertpipe nonblocking! (%d: %s)\n", errno, strerror(errno));
f = &ast_null_frame;
goto done;
}
}
read(chan->alertpipe[0], &blah, sizeof(blah));
}
#ifdef HAVE_ZAPTEL
if (chan->timingfd > -1 && chan->fdno == AST_TIMING_FD && ast_test_flag(chan, AST_FLAG_EXCEPTION)) {