From patchwork Thu Nov 15 17:58:18 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 10684803 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 73F871759 for ; Thu, 15 Nov 2018 18:02:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 658642CEBD for ; Thu, 15 Nov 2018 18:02:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 59FC72CEC4; Thu, 15 Nov 2018 18:02:14 +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 F0ADE2CEC0 for ; Thu, 15 Nov 2018 18:02:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388351AbeKPELB (ORCPT ); Thu, 15 Nov 2018 23:11:01 -0500 Received: from mga05.intel.com ([192.55.52.43]:28722 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726746AbeKPELB (ORCPT ); Thu, 15 Nov 2018 23:11:01 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Nov 2018 10:02:10 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,237,1539673200"; d="scan'208";a="91428166" Received: from unknown (HELO localhost.lm.intel.com) ([10.232.112.69]) by orsmga006.jf.intel.com with ESMTP; 15 Nov 2018 10:02:10 -0800 From: Keith Busch To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Cc: Jens Axboe , Martin Petersen , Bart Van Assche , Keith Busch Subject: [PATCHv3 1/3] blk-mq: Return true if request was completed Date: Thu, 15 Nov 2018 10:58:18 -0700 Message-Id: <20181115175820.13391-2-keith.busch@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20181115175820.13391-1-keith.busch@intel.com> References: <20181115175820.13391-1-keith.busch@intel.com> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP A driver may have internal state to cleanup if we're pretending a request didn't complete. Return 'false' if the command wasn't actually completed due to the timeout error injection, and true otherwise. Signed-off-by: Keith Busch Reviewed-by: Christoph Hellwig --- block/blk-mq.c | 5 +++-- include/linux/blk-mq.h | 2 +- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 352051ea30f7..1fb0f2050d31 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -633,11 +633,12 @@ static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx) * Ends all I/O on a request. It does not handle partial completions. * The actual completion happens out-of-order, through a IPI handler. **/ -void blk_mq_complete_request(struct request *rq) +bool blk_mq_complete_request(struct request *rq) { if (unlikely(blk_should_fake_timeout(rq->q))) - return; + return false; __blk_mq_complete_request(rq); + return true; } EXPORT_SYMBOL(blk_mq_complete_request); diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 929e8abc5535..f0dc26fc86a9 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -298,7 +298,7 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool at_head, bool kick_requeue_list); void blk_mq_kick_requeue_list(struct request_queue *q); void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs); -void blk_mq_complete_request(struct request *rq); +bool blk_mq_complete_request(struct request *rq); bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list, struct bio *bio); bool blk_mq_queue_stopped(struct request_queue *q); From patchwork Thu Nov 15 17:58:19 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 10684795 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 6CA4413BB for ; Thu, 15 Nov 2018 18:02:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5EFE02CEBB for ; Thu, 15 Nov 2018 18:02:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 52D3A2CEC4; Thu, 15 Nov 2018 18:02:13 +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 2E8B62CEBB for ; Thu, 15 Nov 2018 18:02:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388388AbeKPELB (ORCPT ); Thu, 15 Nov 2018 23:11:01 -0500 Received: from mga05.intel.com ([192.55.52.43]:28722 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726453AbeKPELB (ORCPT ); Thu, 15 Nov 2018 23:11:01 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Nov 2018 10:02:11 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,237,1539673200"; d="scan'208";a="91428169" Received: from unknown (HELO localhost.lm.intel.com) ([10.232.112.69]) by orsmga006.jf.intel.com with ESMTP; 15 Nov 2018 10:02:10 -0800 From: Keith Busch To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Cc: Jens Axboe , Martin Petersen , Bart Van Assche , Keith Busch Subject: [PATCHv3 2/3] scsi: Do not rely on blk-mq for double completions Date: Thu, 15 Nov 2018 10:58:19 -0700 Message-Id: <20181115175820.13391-3-keith.busch@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20181115175820.13391-1-keith.busch@intel.com> References: <20181115175820.13391-1-keith.busch@intel.com> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The scsi timeout error handling had been directly updating the block layer's request state to prevent a error handling and a natural completion from completing the same request twice. Fix this layering violation by having scsi control the fate of its commands with scsi owned flags rather than use blk-mq's. Signed-off-by: Keith Busch --- drivers/scsi/scsi_error.c | 22 +++++++++++----------- drivers/scsi/scsi_lib.c | 6 +++++- include/scsi/scsi_cmnd.h | 5 ++++- 3 files changed, 20 insertions(+), 13 deletions(-) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index dd338a8cd275..e92e088f636f 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -297,19 +297,19 @@ enum blk_eh_timer_return scsi_times_out(struct request *req) if (rtn == BLK_EH_DONE) { /* - * For blk-mq, we must set the request state to complete now - * before sending the request to the scsi error handler. This - * will prevent a use-after-free in the event the LLD manages - * to complete the request before the error handler finishes - * processing this timed out request. + * Set the command to complete first in order to prevent a real + * completion from releasing the command while error handling + * is using it. If the command was already completed, then the + * lower level driver beat the timeout handler, and it is safe + * to return without escalating error recovery. * - * If the request was already completed, then the LLD beat the - * time out handler from transferring the request to the scsi - * error handler. In that case we can return immediately as no - * further action is required. + * If timeout handling lost the race to a real completion, the + * block layer may ignore that due to a fake timeout injection, + * so return RESET_TIMER to allow error handling another shot + * at this command. */ - if (!blk_mq_mark_complete(req)) - return rtn; + if (test_and_set_bit(__SCMD_COMPLETE, &scmd->flags)) + return BLK_EH_RESET_TIMER; if (scsi_abort_command(scmd) != SUCCESS) { set_host_byte(scmd, DID_TIME_OUT); scsi_eh_scmd_add(scmd); diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 5d83a162d03b..c1d5e4e36125 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1635,8 +1635,11 @@ static blk_status_t scsi_mq_prep_fn(struct request *req) static void scsi_mq_done(struct scsi_cmnd *cmd) { + if (unlikely(test_and_set_bit(__SCMD_COMPLETE, &cmd->flags))) + return; trace_scsi_dispatch_cmd_done(cmd); - blk_mq_complete_request(cmd->request); + if (unlikely(!blk_mq_complete_request(cmd->request))) + clear_bit(__SCMD_COMPLETE, &cmd->flags); } static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx) @@ -1701,6 +1704,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, goto out_dec_host_busy; req->rq_flags |= RQF_DONTPREP; } else { + cmd->flags &= ~SCMD_COMPLETE; blk_mq_start_request(req); } diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index d6fd2aba0380..ded7c7194a28 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -58,6 +58,9 @@ struct scsi_pointer { #define SCMD_TAGGED (1 << 0) #define SCMD_UNCHECKED_ISA_DMA (1 << 1) #define SCMD_INITIALIZED (1 << 2) + +#define __SCMD_COMPLETE 3 +#define SCMD_COMPLETE (1 << __SCMD_COMPLETE) /* flags preserved across unprep / reprep */ #define SCMD_PRESERVED_FLAGS (SCMD_UNCHECKED_ISA_DMA | SCMD_INITIALIZED) @@ -144,7 +147,7 @@ struct scsi_cmnd { * to be at an address < 16Mb). */ int result; /* Status code from lower level driver */ - int flags; /* Command flags */ + unsigned long flags; /* Command flags */ unsigned char tag; /* SCSI-II queued command tag */ }; From patchwork Thu Nov 15 17:58:20 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 10684797 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 AA29B1759 for ; Thu, 15 Nov 2018 18:02:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9B7D22CEC0 for ; Thu, 15 Nov 2018 18:02:13 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8F8402CEC4; Thu, 15 Nov 2018 18:02:13 +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 1CBF52CEC1 for ; Thu, 15 Nov 2018 18:02:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388585AbeKPELC (ORCPT ); Thu, 15 Nov 2018 23:11:02 -0500 Received: from mga05.intel.com ([192.55.52.43]:28722 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726453AbeKPELB (ORCPT ); Thu, 15 Nov 2018 23:11:01 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Nov 2018 10:02:11 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,237,1539673200"; d="scan'208";a="91428173" Received: from unknown (HELO localhost.lm.intel.com) ([10.232.112.69]) by orsmga006.jf.intel.com with ESMTP; 15 Nov 2018 10:02:11 -0800 From: Keith Busch To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Cc: Jens Axboe , Martin Petersen , Bart Van Assche , Keith Busch Subject: [PATCHv3 3/3] blk-mq: Simplify request completion state Date: Thu, 15 Nov 2018 10:58:20 -0700 Message-Id: <20181115175820.13391-4-keith.busch@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20181115175820.13391-1-keith.busch@intel.com> References: <20181115175820.13391-1-keith.busch@intel.com> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There are no more users relying on blk-mq request states to prevent double completions, so replace the relatively expensive cmpxchg operation with WRITE_ONCE. Signed-off-by: Keith Busch Reviewed-by: Christoph Hellwig --- block/blk-mq.c | 4 +--- include/linux/blk-mq.h | 14 -------------- 2 files changed, 1 insertion(+), 17 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 1fb0f2050d31..ce769132cfbe 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -568,9 +568,7 @@ static void __blk_mq_complete_request(struct request *rq) bool shared = false; int cpu; - if (!blk_mq_mark_complete(rq)) - return; - + WRITE_ONCE(rq->state, MQ_RQ_COMPLETE); /* * Most of single queue controllers, there is only one irq vector * for handling IO completion, and the only irq's affinity is set diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index f0dc26fc86a9..9b5528fcdd45 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -329,20 +329,6 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q); unsigned int blk_mq_rq_cpu(struct request *rq); -/** - * blk_mq_mark_complete() - Set request state to complete - * @rq: request to set to complete state - * - * Returns true if request state was successfully set to complete. If - * successful, the caller is responsibile for seeing this request is ended, as - * blk_mq_complete_request will not work again. - */ -static inline bool blk_mq_mark_complete(struct request *rq) -{ - return cmpxchg(&rq->state, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE) == - MQ_RQ_IN_FLIGHT; -} - /* * Driver command data is immediately after the request. So subtract request * size to get back to the original request, add request size to get the PDU.