From patchwork Tue Nov 13 18:57:11 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 10681391 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 7D76F18F0 for ; Tue, 13 Nov 2018 19:00:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 72F812B38C for ; Tue, 13 Nov 2018 19:00:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 67A122B3EA; Tue, 13 Nov 2018 19:00:53 +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=unavailable 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 0B83F2B3EC for ; Tue, 13 Nov 2018 19:00:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725783AbeKNFAR (ORCPT ); Wed, 14 Nov 2018 00:00:17 -0500 Received: from mga01.intel.com ([192.55.52.88]:64226 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725748AbeKNFAR (ORCPT ); Wed, 14 Nov 2018 00:00:17 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Nov 2018 11:00:51 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,229,1539673200"; d="scan'208";a="96018828" Received: from unknown (HELO localhost.lm.intel.com) ([10.232.112.69]) by FMSMGA003.fm.intel.com with ESMTP; 13 Nov 2018 11:00:51 -0800 From: Keith Busch To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Cc: Keith Busch Subject: [PATCH 1/2] scsi: Do not rely on blk-mq for double completions Date: Tue, 13 Nov 2018 11:57:11 -0700 Message-Id: <20181113185712.10063-1-keith.busch@intel.com> X-Mailer: git-send-email 2.13.6 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 request state to prevent a natural completion and error handling 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 | 17 +++-------------- drivers/scsi/scsi_lib.c | 11 +++++++++++ include/scsi/scsi_cmnd.h | 5 ++++- 3 files changed, 18 insertions(+), 15 deletions(-) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index dd338a8cd275..6156f45c2c80 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -204,6 +204,9 @@ scsi_abort_command(struct scsi_cmnd *scmd) shost->last_reset = jiffies; spin_unlock_irqrestore(shost->host_lock, flags); + if (test_and_set_bit(__SCMD_COMPLETE, &scmd->flags)) + return SUCCESS; + scmd->eh_eflags |= SCSI_EH_ABORT_SCHEDULED; SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd, "abort scheduled\n")); @@ -296,20 +299,6 @@ enum blk_eh_timer_return scsi_times_out(struct request *req) rtn = host->hostt->eh_timed_out(scmd); 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. - * - * 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 (!blk_mq_mark_complete(req)) - return rtn; 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 61babcb269ab..c680171ca201 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1635,8 +1635,18 @@ static blk_status_t scsi_mq_prep_fn(struct request *req) static void scsi_mq_done(struct scsi_cmnd *cmd) { + if (test_and_set_bit(__SCMD_COMPLETE, &cmd->flags)) + return; trace_scsi_dispatch_cmd_done(cmd); blk_mq_complete_request(cmd->request); + +#ifdef CONFIG_FAIL_IO_TIMEOUT + /* + * Clearing complete here serves only to allow the desired recovery to + * escalate on blk_rq_should_fake_timeout()'s error injection. + */ + clear_bit(__SCMD_COMPLETE, &cmd->flags); +#endif } static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx) @@ -1701,6 +1711,7 @@ 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 Tue Nov 13 18:57:12 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 10681393 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 9DCB913BF for ; Tue, 13 Nov 2018 19:00:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 941D62B38C for ; Tue, 13 Nov 2018 19:00:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 882572B3E6; Tue, 13 Nov 2018 19:00:53 +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 2C4762B3B4 for ; Tue, 13 Nov 2018 19:00:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725794AbeKNFAR (ORCPT ); Wed, 14 Nov 2018 00:00:17 -0500 Received: from mga01.intel.com ([192.55.52.88]:64226 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725750AbeKNFAR (ORCPT ); Wed, 14 Nov 2018 00:00:17 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Nov 2018 11:00:51 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,229,1539673200"; d="scan'208";a="96018832" Received: from unknown (HELO localhost.lm.intel.com) ([10.232.112.69]) by FMSMGA003.fm.intel.com with ESMTP; 13 Nov 2018 11:00:51 -0800 From: Keith Busch To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org Cc: Keith Busch Subject: [PATCH 2/2] blk-mq: Simplify request completion state Date: Tue, 13 Nov 2018 11:57:12 -0700 Message-Id: <20181113185712.10063-2-keith.busch@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20181113185712.10063-1-keith.busch@intel.com> References: <20181113185712.10063-1-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 --- 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 03b1af0151ca..6c546a021803 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 e32e9293e5a0..1a857c6e17fa 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -237,20 +237,6 @@ 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.