From: Pavel Shilovsky pshilov@microsoft.com
commit 7b71843fa7028475b052107664cbe120156a2cfc upstream.
When an OPEN command is cancelled we mark a mid as cancelled and let the demultiplex thread process it by closing an open handle. The problem is there is a race between a system call thread and the demultiplex thread and there may be a situation when the mid has been already processed before it is set as cancelled.
Fix this by processing cancelled requests when mids are being destroyed which means that there is only one thread referencing a particular mid. Also set mids as cancelled unconditionally on their state.
Cc: Stable stable@vger.kernel.org Tested-by: Frank Sorenson sorenson@redhat.com Reviewed-by: Ronnie Sahlberg lsahlber@redhat.com Signed-off-by: Pavel Shilovsky pshilov@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cifs/connect.c | 6 ------ fs/cifs/transport.c | 10 ++++++++-- 2 files changed, 8 insertions(+), 8 deletions(-)
--- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -1222,12 +1222,6 @@ next_pdu: for (i = 0; i < num_mids; i++) { if (mids[i] != NULL) { mids[i]->resp_buf_size = server->pdu_size; - if ((mids[i]->mid_flags & MID_WAIT_CANCELLED) && - mids[i]->mid_state == MID_RESPONSE_RECEIVED && - server->ops->handle_cancelled_mid) - server->ops->handle_cancelled_mid( - mids[i]->resp_buf, - server);
if (!mids[i]->multiRsp || mids[i]->multiEnd) mids[i]->callback(mids[i]); --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -93,8 +93,14 @@ static void _cifs_mid_q_entry_release(st __u16 smb_cmd = le16_to_cpu(midEntry->command); unsigned long now; unsigned long roundtrip_time; - struct TCP_Server_Info *server = midEntry->server; #endif + struct TCP_Server_Info *server = midEntry->server; + + if (midEntry->resp_buf && (midEntry->mid_flags & MID_WAIT_CANCELLED) && + midEntry->mid_state == MID_RESPONSE_RECEIVED && + server->ops->handle_cancelled_mid) + server->ops->handle_cancelled_mid(midEntry->resp_buf, server); + midEntry->mid_state = MID_FREE; atomic_dec(&midCount); if (midEntry->large_buf) @@ -1122,8 +1128,8 @@ compound_send_recv(const unsigned int xi midQ[i]->mid, le16_to_cpu(midQ[i]->command)); send_cancel(server, &rqst[i], midQ[i]); spin_lock(&GlobalMid_Lock); + midQ[i]->mid_flags |= MID_WAIT_CANCELLED; if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) { - midQ[i]->mid_flags |= MID_WAIT_CANCELLED; midQ[i]->callback = cifs_cancelled_callback; cancelled_mid[i] = true; credits[i].value = 0;