From patchwork Tue Oct 24 15:51:38 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Garry X-Patchwork-Id: 10024759 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5C2456035E for ; Tue, 24 Oct 2017 15:07:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4B84328A13 for ; Tue, 24 Oct 2017 15:07:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3FBC228A19; Tue, 24 Oct 2017 15:07:17 +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=-6.9 required=2.0 tests=BAYES_00,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 D3B7628A13 for ; Tue, 24 Oct 2017 15:07:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932403AbdJXPHQ (ORCPT ); Tue, 24 Oct 2017 11:07:16 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:50508 "EHLO huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751398AbdJXPF2 (ORCPT ); Tue, 24 Oct 2017 11:05:28 -0400 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id E7585C3017A17; Tue, 24 Oct 2017 23:05:22 +0800 (CST) Received: from localhost.localdomain (10.67.212.75) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.361.1; Tue, 24 Oct 2017 23:05:17 +0800 From: John Garry To: , CC: , , , , Xiaofei Tan , John Garry Subject: [PATCH 08/19] scsi: hisi_sas: fix the risk of freeing slot twice Date: Tue, 24 Oct 2017 23:51:38 +0800 Message-ID: <1508860309-212397-9-git-send-email-john.garry@huawei.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1508860309-212397-1-git-send-email-john.garry@huawei.com> References: <1508860309-212397-1-git-send-email-john.garry@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.212.75] X-CFilter-Loop: Reflected 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 From: Xiaofei Tan The function hisi_sas_slot_task_free() is used to free the slot and do tidy-up of LLDD resources. The LLDD generally should know the state of a slot and decide when to free it, and it should only be done once. For some scenarios, we really don't know the state, like when TMF timeout. In this case, we check task->lldd_task before calling hisi_sas_slot_task_free(). However, we may miss some scenarios when we should also check task->lldd_task, and it is not SMP safe to check task->lldd_task as we don't protect it within spin lock. This patch is to fix this risk of freeing slot twice, as follows: 1. Check task->lldd_task in the hisi_sas_slot_task_free(), and give up freeing of this time if task->lldd_task is NULL. 2. Set slot->buf to NULL after it is freed. Signed-off-by: Xiaofei Tan Signed-off-by: John Garry --- drivers/scsi/hisi_sas/hisi_sas_main.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c index 2a209e1..6b4dabde 100644 --- a/drivers/scsi/hisi_sas/hisi_sas_main.c +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c @@ -185,13 +185,16 @@ void hisi_sas_slot_task_free(struct hisi_hba *hisi_hba, struct sas_task *task, struct domain_device *device = task->dev; struct hisi_sas_device *sas_dev = device->lldd_dev; + if (!task->lldd_task) + return; + + task->lldd_task = NULL; + if (!sas_protocol_ata(task->task_proto)) if (slot->n_elem) dma_unmap_sg(dev, task->scatter, slot->n_elem, task->data_dir); - task->lldd_task = NULL; - if (sas_dev) atomic64_dec(&sas_dev->running_req); } @@ -199,8 +202,8 @@ void hisi_sas_slot_task_free(struct hisi_hba *hisi_hba, struct sas_task *task, if (slot->buf) dma_pool_free(hisi_hba->buffer_pool, slot->buf, slot->buf_dma); - list_del_init(&slot->entry); + slot->buf = NULL; slot->task = NULL; slot->port = NULL; hisi_sas_slot_index_free(hisi_hba, slot->idx);