From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932401AbdJXPHP (ORCPT ); Tue, 24 Oct 2017 11:07:15 -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 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 Content-Type: text/plain X-Originating-IP: [10.67.212.75] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); -- 1.9.1