From deab4c9f543f27347a99fe5ce3e59077ccf0c338 Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Thu, 21 Nov 2019 11:35:14 -0800 Subject: [PATCH 2/3] CIFS: Do not miss cancelled OPEN responses BugLink: https://bugs.launchpad.net/bugs/1918714 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 Tested-by: Frank Sorenson Reviewed-by: Ronnie Sahlberg Signed-off-by: Pavel Shilovsky Signed-off-by: Steve French (backported from commit 7b71843fa7028475b052107664cbe120156a2cfc) [ fs/cifs/transport.c has changed significantly, I pieced in the intended changes to the old function DeleteMidQEntry() ] Signed-off-by: Tim Gardner --- fs/cifs/connect.c | 7 ------- fs/cifs/transport.c | 9 ++++++++- 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index c96b9d60f625..7f8a65d325b8 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -996,13 +996,6 @@ cifs_demultiplex_thread(void *p) server->lstrp = jiffies; if (mid_entry != NULL) { - if ((mid_entry->mid_flags & MID_WAIT_CANCELLED) && - mid_entry->mid_state == MID_RESPONSE_RECEIVED && - server->ops->handle_cancelled_mid) - server->ops->handle_cancelled_mid( - mid_entry->resp_buf, - server); - if (!mid_entry->multiRsp || mid_entry->multiEnd) mid_entry->callback(mid_entry); diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 22d421054303..143b2de71dec 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -100,6 +100,13 @@ DeleteMidQEntry(struct mid_q_entry *midEntry) __le16 command = midEntry->server->vals->lock_cmd; unsigned long now; #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) @@ -768,8 +775,8 @@ cifs_send_recv(const unsigned int xid, struct cifs_ses *ses, cifs_dbg(FYI, "Cancelling wait for mid %llu\n", midQ->mid); send_cancel(ses->server, rqst, midQ); spin_lock(&GlobalMid_Lock); + midQ->mid_flags |= MID_WAIT_CANCELLED; if (midQ->mid_state == MID_REQUEST_SUBMITTED) { - midQ->mid_flags |= MID_WAIT_CANCELLED; midQ->callback = DeleteMidQEntry; spin_unlock(&GlobalMid_Lock); add_credits(ses->server, 1, optype); -- 2.17.1