Re: [Qemu-devel] [PATCH] nbd-client: fix hang after server closes connection

[Stefan Hajnoczi <stefanha@redhat.com>]

On Mon, Aug 21, 2017 at 05:15:39PM +0100, Stefan Hajnoczi wrote:
> Commit 72b6ffc76653214b69a94a7b1643ff80df134486 ("nbd-client: Fix
> regression when server sends garbage") improved NBD client behavior when
> the connection enters a broken state.
> 
> The following still does not behave as expected:
> 
>   $ qemu-nbd -p 1234 -x drive0 -f qcow2 test.qcow2
>   $ qemu-system-x86_64 -M accel=kvm -m 1G \
>         -drive if=virtio,id=drive0,file=nbd://localhost:1234/drive0,format=raw
>   $ pkill qemu-nbd
>   (qemu) quit
>   ...hang...
> 
> QEMU should be able to quit even when the connection was previously
> closed by the NBD server.  Currently the nbd_read_reply_entry()
> coroutine terminates without letting in-flight requests know that the
> connection is dead.
> 
> This patch flags the connection as dead so in-flight requests can
> complete.
> 
> Reported-by: Longxiang Lyu <lolyu@redhat.com>
> Cc: Eric Blake <eblake@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  block/nbd-client.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)

This patch is superceded by "[PATCH] nbd-client: avoid spurious
qio_channel_yield() re-entry".

Stefan