xfs_repair: clear pthread_t when pthread_create fails

pf_queuing_worker and pf_create_prefetch_thread both try to handle
thread creation failure gracefully, but assume that pthread_create
doesn't modify the pthread_t when it fails.

From the pthread_create man page:
On  success,  pthread_create() returns 0; on error, it returns an error
number, and the contents of *thread are undefined.

In fact, glibc's pthread_create writes the pthread_t value before
calling clone().  When we join the created threads in
cleanup_inode_prefetch and the cleanup stage of pf_queuing_worker, we
assume that if the pthread_t is nonzero that it's a valid thread handle
and end up crashing in pthread_join.

This patch zeros out the handle after pthread_create failure.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/repair/prefetch.c b/repair/prefetch.c
index ff506061389eeb06ca72db0a37466fcbab4e399a..044fab2e537bb77bde2d2e9cc50f1f4089a0c198 100644 (file)
--- a/repair/prefetch.c
+++ b/repair/prefetch.c
@@ -703,6 +703,7 @@ pf_queuing_worker(
                if (err != 0) {
                        do_warn(_("failed to create prefetch thread: %s\n"),
                                strerror(err));
+                       args->io_threads[i] = 0;
                        if (i == 0) {
                                pf_start_processing(args);
                                return NULL;
@@ -816,6 +817,7 @@ pf_create_prefetch_thread(
        if (err != 0) {
                do_warn(_("failed to create prefetch thread: %s\n"),
                        strerror(err));
+               args->queuing_thread = 0;
                cleanup_inode_prefetch(args);
        }