Re: [Qemu-devel] [PATCH v2 6/7] iotests: amend QEMU NBD process synchronization

[Roman Kagan <rkagan@virtuozzo.com>]

On Thu, Jun 13, 2019 at 12:59:53PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> 11.06.2019 21:02, Andrey Shinkevich wrote:
> > Processes are dying harder under the Valgring. It results in counting
> > the dying process as a newborn one. Make it sure that old NBD job get
> > finished before starting a new one.
> > 
> > Suggested-by: Roman Kagan <rkagan@virtuozzo.com>
> > Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
> > ---
> >   tests/qemu-iotests/common.nbd | 6 ++++++
> >   1 file changed, 6 insertions(+)
> > 
> > diff --git a/tests/qemu-iotests/common.nbd b/tests/qemu-iotests/common.nbd
> > index 25fc9ff..e3dcc60 100644
> > --- a/tests/qemu-iotests/common.nbd
> > +++ b/tests/qemu-iotests/common.nbd
> > @@ -22,6 +22,7 @@
> >   nbd_unix_socket="${TEST_DIR}/qemu-nbd.sock"
> >   nbd_tcp_addr="127.0.0.1"
> >   nbd_pid_file="${TEST_DIR}/qemu-nbd.pid"
> > +nbd_job_pid=""
> >   
> >   nbd_server_stop()
> >   {
> > @@ -33,6 +34,9 @@ nbd_server_stop()
> >               kill "$NBD_PID"
> >           fi
> >       fi
> 
> Honestly, I don't understand the problem from commit message, but anyway comment
> should be added here, to mark that this is for valgrind... But you don't check for
> VALGRIND enabled.. I it intentional?

It is.  The problem this patch fixes exists regardless of valgrind.
valgrind just makes it easier to notice.  See my reply to the patch
itself.

Roman.

> 
> > +    if [ -n "$nbd_job_pid" ] && kill -s 0 "$nbd_job_pid" 2>/dev/null; then
> > +        wait "$nbd_job_pid"
> > +    fi
> >       rm -f "$nbd_unix_socket"
> >   }
> >   
> > @@ -61,6 +65,7 @@ nbd_server_start_unix_socket()
> >   {
> >       nbd_server_stop
> >       $QEMU_NBD -v -t -k "$nbd_unix_socket" "$@" &
> > +    nbd_job_pid=$!
> >       nbd_server_wait_for_unix_socket $!
> >   }
> >   
> > @@ -105,5 +110,6 @@ nbd_server_start_tcp_socket()
> >   {
> >       nbd_server_stop
> >       $QEMU_NBD -v -t -b $nbd_tcp_addr -p $nbd_tcp_port "$@" &
> > +    nbd_job_pid=$!
> >       nbd_server_wait_for_tcp_socket $!
> >   }
> > 
> 
> 
> -- 
> Best regards,
> Vladimir