From patchwork Thu Aug 30 00:13:00 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ronnie Sahlberg X-Patchwork-Id: 10581093 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 08E845A4 for ; Thu, 30 Aug 2018 00:13:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EE0C428627 for ; Thu, 30 Aug 2018 00:13:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E261C28676; Thu, 30 Aug 2018 00:13:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8EB2828627 for ; Thu, 30 Aug 2018 00:13:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725836AbeH3EMl (ORCPT ); Thu, 30 Aug 2018 00:12:41 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47114 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725834AbeH3EMl (ORCPT ); Thu, 30 Aug 2018 00:12:41 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4D0F540241C0; Thu, 30 Aug 2018 00:13:17 +0000 (UTC) Received: from test1135.test.redhat.com (vpn2-54-77.bne.redhat.com [10.64.54.77]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5A8512026E18; Thu, 30 Aug 2018 00:13:16 +0000 (UTC) From: Ronnie Sahlberg To: linux-cifs Cc: Steve French Subject: [PATCH 2/2] cifs: only wake the thread for the very last PDU in a compound Date: Thu, 30 Aug 2018 10:13:00 +1000 Message-Id: <20180830001300.28082-3-lsahlber@redhat.com> In-Reply-To: <20180830001300.28082-1-lsahlber@redhat.com> References: <20180830001300.28082-1-lsahlber@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 30 Aug 2018 00:13:17 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Thu, 30 Aug 2018 00:13:17 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'lsahlber@redhat.com' RCPT:'' Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP For compounded PDUs we whould only wake the waiting thread for the very last PDU of the compound. We do this so that we are guaranteed that the demultiplex_thread will not process or access any of those MIDs any more once the send/recv thread starts processing. Else there is a race where at the end of the send/recv processing we will try to delete all the mids of the compound. If the multiplex thread still has other mids to process at this point for this compound this can lead to an oops. Signed-off-by: Ronnie Sahlberg Reviewed-by: Pavel Shilovsky --- fs/cifs/transport.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 9cc9a127749e..b48f43963da6 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -773,6 +773,11 @@ cifs_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst) return mid; } +static void +cifs_noop_callback(struct mid_q_entry *mid) +{ +} + int compound_send_recv(const unsigned int xid, struct cifs_ses *ses, const int flags, const int num_rqst, struct smb_rqst *rqst, @@ -827,8 +832,13 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, } midQ[i]->mid_state = MID_REQUEST_SUBMITTED; + /* + * We don't invoke the callback compounds unless it is the last + * request. + */ + if (i < num_rqst - 1) + midQ[i]->callback = cifs_noop_callback; } - cifs_in_send_inc(ses->server); rc = smb_send_rqst(ses->server, num_rqst, rqst, flags); cifs_in_send_dec(ses->server); @@ -909,6 +919,12 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, midQ[i]->resp_buf = NULL; } out: + /* + * This will dequeue all mids. After this it is important that the + * demultiplex_thread will not process any of these mids any futher. + * This is prevented above by using a noop callback that will not + * wake this thread except for the very last PDU. + */ for (i = 0; i < num_rqst; i++) cifs_delete_mid(midQ[i]); add_credits(ses->server, credits, optype);