linux-kernel - [PATCH] afs: Fix missing timeout reset

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Date:   Tue, 19 Nov 2019 21:00:36 +0000
From:   David Howells <dhowells@...hat.com>
To:     torvalds@...ux-foundation.org
Cc:     dhowells@...hat.com, marc.dionne@...istor.com,
        linux-afs@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] afs: Fix missing timeout reset

In afs_wait_for_call_to_complete(), rather than immediately aborting an
operation if a signal occurs, the code attempts to wait for it to complete,
using a schedule timeout of 2*RTT (or min 2 jiffies) and a check that we're
still receiving relevant packets from the server before we consider
aborting the call.  We may even ping the server to check on the status of
the call.

However, there's a missing timeout reset in the event that we do actually
get a packet to process, such that if we then get a couple of short stalls,
we then time out when progress is actually being made.

Fix this by resetting the timeout any time we get something to process.  If
it's the failure of the call then the call state will get changed and we'll
exit the loop shortly thereafter.

A symptom of this is data fetches and stores failing with EINTR when they
really shouldn't.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@...hat.com>
Reviewed-by: Marc Dionne <marc.dionne@...istor.com>
---

 fs/afs/rxrpc.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 0e5269374ac1..61498d9f06ef 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -637,6 +637,7 @@ long afs_wait_for_call_to_complete(struct afs_call *call,
 			call->need_attention = false;
 			__set_current_state(TASK_RUNNING);
 			afs_deliver_to_call(call);
+			timeout = rtt2;
 			continue;
 		}