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[Qemu-devel] [for-2.9 PATCH 2/3] 9pfs: cancel active PDUs in virtfs_rese
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [for-2.9 PATCH 2/3] 9pfs: cancel active PDUs in virtfs_reset() |
Date: |
Fri, 31 Mar 2017 13:27:15 +0200 |
User-agent: |
StGit/0.17.1-20-gc0b1b-dirty |
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 <address@hidden>
---
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);
}