> -----Original Message-----
> From: Greg Kurz [mailto:gr...@kaod.org]
> Sent: Friday, March 31, 2017 7:27 PM
> To: qemu-devel@nongnu.org
> Cc: Eric Blake; 李强; Greg Kurz
> Subject: [for-2.9 PATCH 2/3] 9pfs: cancel active PDUs in virtfs_reset()
>
> According to the 9P spec [1], the version operation should abort any
> outstanding I/O and clunk all fids, so that a new session may be started in a
> clean state.
>
> The current code tries to clunk and free fids, but it doesn't wait for active
> PDUs
> to complete. This can cause an I/O to actually complete after the new session
> has begun, and confuse the client.
>
> This patch modifies virtfs_reset() so that it explicitely cancels and waits
> for
> inflight requests to terminate. All fids should thus be unreferenced and
> ready to
> be freed. Let's make it clear with a an assertion.
>
> [1] http://man.cat-v.org/plan_9/5/version
>
> Signed-off-by: Greg Kurz <gr...@kaod.org>
> ---
Reviewed-by: Li Qiang <liqiang...@360.cn>
> hw/9pfs/9p.c | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index cc109367b030..86ed9065c4e2
> 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -536,9 +536,29 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu)
> {
> V9fsState *s = pdu->s;
> V9fsFidState *fidp;
> + bool done = false;
> +
> + /* Drain any outstanding I/O */
> + while (!done) {
> + V9fsPDU *cancel_pdu;
> +
> + done = true;
> + QLIST_FOREACH(cancel_pdu, &s->active_list, next) {
> + if (cancel_pdu != pdu) {
> + done = false;
> + cancel_pdu->cancelled = 1;
> + qemu_co_queue_wait(&cancel_pdu->complete, NULL);
> + cancel_pdu->cancelled = 0;
> + pdu_free(cancel_pdu);
> + break;
> + }
> + }
> + }
>
> /* Free all fids */
> while (s->fid_list) {
> + assert(!fidp->ref);
> +
> /* Get fid */
> fidp = s->fid_list;
> fidp->ref++;
> @@ -670,7 +690,7 @@ static void coroutine_fn pdu_complete(V9fsPDU *pdu,
> ssize_t len)
>
> pdu_push_and_notify(pdu);
>
> - /* Now wakeup anybody waiting in flush for this request */
> + /* Now wakeup anybody waiting in flush or reset for this request */
> if (!qemu_co_queue_next(&pdu->complete)) {
> pdu_free(pdu);
> }
