On 14/04/2016 12:20, Denis V. Lunev wrote:
> From: Pavel Butsykin <pbutsy...@virtuozzo.com>
>
> From time to time qemu-nbd is crashing on the following assert:
> assert(state == TERMINATING);
> nbd_export_closed
> nbd_export_put
> main
> and the state at the moment of the crash is evaluated to TERMINATE.
>
> During shutdown process of the client the nbd_client_thread thread sends
> SIGTERM signal and the main thread calls the nbd_client_closed callback.
> If the SIGTERM callback will be executed after change the state to
> TERMINATING, then the state will once again be TERMINATE.
>
> To solve the issue, we must change the state to TERMINATE only if the state
> is RUNNING. In the other case we are shutting down already.
>
> Signed-off-by: Pavel Butsykin <pbutsy...@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <d...@openvz.org>
> CC: Paolo Bonzini <pbonz...@redhat.com>
> ---
> qemu-nbd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/qemu-nbd.c b/qemu-nbd.c
> index ca4a724..956013f 100644
> --- a/qemu-nbd.c
> +++ b/qemu-nbd.c
> @@ -213,7 +213,7 @@ static int find_partition(BlockBackend *blk, int
> partition,
>
> static void termsig_handler(int signum)
> {
> - state = TERMINATE;
> + atomic_cmpxchg(&state, RUNNING, TERMINATE);
Just a simple "if" is enough (the rest of the file is not using any of
atomic{mb_,}{read,set}.
I'm not able to send further pull requests for 2.6, can the block
maintainers help?
Paolo
> qemu_notify_event();
> }
>
>
