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authorStefan Hajnoczi <stefanha@redhat.com>2019-10-03 11:01:03 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2019-10-14 09:48:01 +0100
commit69de48445a0d6169f1e2a6c5bfab994e1c810e33 (patch)
tree3b47dc751f350d2361f5bbd4fccc271088f0e04f /tests/iothread.c
parent98b2e3c9ab3abfe476a2b02f8f51813edb90e72d (diff)
test-bdrv-drain: fix iothread_join() hang
tests/test-bdrv-drain can hang in tests/iothread.c:iothread_run(): while (!atomic_read(&iothread->stopping)) { aio_poll(iothread->ctx, true); } The iothread_join() function works as follows: void iothread_join(IOThread *iothread) { iothread->stopping = true; aio_notify(iothread->ctx); qemu_thread_join(&iothread->thread); If iothread_run() checks iothread->stopping before the iothread_join() thread sets stopping to true, then aio_notify() may be optimized away and iothread_run() hangs forever in aio_poll(). The correct way to change iothread->stopping is from a BH that executes within iothread_run(). This ensures that iothread->stopping is checked after we set it to true. This was already fixed for ./iothread.c (note this is a different source file!) by commit 2362a28ea11c145e1a13ae79342d76dc118a72a6 ("iothread: fix iothread_stop() race condition"), but not for tests/iothread.c. Fixes: 0c330a734b51c177ab8488932ac3b0c4d63a718a ("aio: introduce aio_co_schedule and aio_co_wake") Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20191003100103.331-1-stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'tests/iothread.c')
-rw-r--r--tests/iothread.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/tests/iothread.c b/tests/iothread.c
index 777d9eea46..13c9fdcd8d 100644
--- a/tests/iothread.c
+++ b/tests/iothread.c
@@ -55,10 +55,16 @@ static void *iothread_run(void *opaque)
return NULL;
}
-void iothread_join(IOThread *iothread)
+static void iothread_stop_bh(void *opaque)
{
+ IOThread *iothread = opaque;
+
iothread->stopping = true;
- aio_notify(iothread->ctx);
+}
+
+void iothread_join(IOThread *iothread)
+{
+ aio_bh_schedule_oneshot(iothread->ctx, iothread_stop_bh, iothread);
qemu_thread_join(&iothread->thread);
qemu_cond_destroy(&iothread->init_done_cond);
qemu_mutex_destroy(&iothread->init_done_lock);