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cifs: handle cancelled requests better

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Currently, when a request is cancelled via signal, we delete the mid
immediately. If the request was already transmitted however, the client
is still likely to receive a response. When it does, it won't recognize
it however and will pop a printk.

It's also a little dangerous to just delete the mid entry like this. We
may end up reusing that mid. If we do then we could potentially get the
response from the first request confused with the later one.

Prevent the reuse of mids by marking them as cancelled and keeping them
on the pending_mid_q list. If the reply comes in, we'll delete it from
the list then. If it never comes, then we'll delete it at reconnect
or when cifsd comes down.

Reviewed-by: Pavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Jeff Layton 2011-01-28 07:08:28 -05:00 committed by Steve French
parent 58b8a5b45a
commit 1be912dde7
1 changed files with 36 additions and 7 deletions
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43
fs/cifs/transport.c
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@ -579,8 +579,17 @@ SendReceive2(const unsigned int xid, struct cifsSesInfo *ses,
goto out;
rc = wait_for_response(ses->server, midQ);
if (rc != 0)
goto out;
if (rc != 0) {
spin_lock(&GlobalMid_Lock);
if (midQ->midState == MID_REQUEST_SUBMITTED) {
midQ->callback = DeleteMidQEntry;
spin_unlock(&GlobalMid_Lock);
atomic_dec(&ses->server->inFlight);
wake_up(&ses->server->request_q);
return rc;
}
spin_unlock(&GlobalMid_Lock);
}
rc = sync_mid_result(midQ, ses->server);
if (rc != 0) {
@ -724,8 +733,18 @@ SendReceive(const unsigned int xid, struct cifsSesInfo *ses,
goto out;
rc = wait_for_response(ses->server, midQ);
if (rc != 0)
goto out;
if (rc != 0) {
spin_lock(&GlobalMid_Lock);
if (midQ->midState == MID_REQUEST_SUBMITTED) {
/* no longer considered to be "in-flight" */
midQ->callback = DeleteMidQEntry;
spin_unlock(&GlobalMid_Lock);
atomic_dec(&ses->server->inFlight);
wake_up(&ses->server->request_q);
return rc;
}
spin_unlock(&GlobalMid_Lock);
}
rc = sync_mid_result(midQ, ses->server);
if (rc != 0) {
@ -922,10 +941,20 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifsTconInfo *tcon,
}
}
if (wait_for_response(ses->server, midQ) == 0) {
/* We got the response - restart system call. */
rstart = 1;
rc = wait_for_response(ses->server, midQ);
if (rc) {
spin_lock(&GlobalMid_Lock);
if (midQ->midState == MID_REQUEST_SUBMITTED) {
/* no longer considered to be "in-flight" */
midQ->callback = DeleteMidQEntry;
spin_unlock(&GlobalMid_Lock);
return rc;
}
spin_unlock(&GlobalMid_Lock);
}
/* We got the response - restart system call. */
rstart = 1;
}
rc = sync_mid_result(midQ, ses->server);