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[PULL,01/17] vl.c/exit: pause cpus before closing block devices

Message ID 1501604245-33460-2-git-send-email-pbonzini@redhat.com
State New
Headers show

Commit Message

Paolo Bonzini Aug. 1, 2017, 4:17 p.m. UTC 
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

There's a rare exit seg if the guest is accessing
IO during exit.
It's always hitting the atomic_inc(&bs->in_flight) with a NULL
bs. This was added recently in 99723548  but I don't see it
as the cause.

Flip vl.c around so we pause the cpus before closing the block devices,
that way we shouldn't have anything trying to access them when
they're gone.

This was originally Red Hat bz https://bugzilla.redhat.com/show_bug.cgi?id=1451015

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reported-by: Cong Li <coli@redhat.com>

--
This is a very rare race, I'll leave it running in a loop to see if
we hit anything else and to check this really fixes it.

I do worry if there are other cases that can trigger this - e.g.
hot-unplug or ejecting a CD.

Message-Id: <20170713190116.21608-1-dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 vl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox

Patch

diff --git a/vl.c b/vl.c
index fb6b2ef..dd803fc 100644
--- a/vl.c
+++ b/vl.c
@@ -4787,8 +4787,8 @@  int main(int argc, char **argv, char **envp)
     replay_disable_events();
     iothread_stop_all();
 
-    bdrv_close_all();
     pause_all_vcpus();
+    bdrv_close_all();
     res_free();
 
     /* vhost-user must be cleaned up before chardevs.  */