From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E66BBC00A89 for ; Tue, 3 Nov 2020 01:23:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B20F2063A for ; Tue, 3 Nov 2020 01:23:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604366586; bh=3cwa2+oW48qbbKajQym3cjbPzZISxKfmoExe6aZKujk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=PON5Z9FZzKAKIF1cDSn3pw8GxKTFrcwIA7t6lxoeECGZktZKuSX9s5sehSLat7F1Y 7roFFmIP1NG2z5u2WDt7YbtrvSalYdrzRgWsWrQg7L3jkr4jsO7woYIvoYbSMLBI8P PJztrp3X9z2Ou5tWnmMGLxZVn68rnFd+yRt2R350= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727982AbgKCBXF (ORCPT ); Mon, 2 Nov 2020 20:23:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:35938 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728223AbgKCBUt (ORCPT ); Mon, 2 Nov 2020 20:20:49 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 194B422400; Tue, 3 Nov 2020 01:20:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604366449; bh=3cwa2+oW48qbbKajQym3cjbPzZISxKfmoExe6aZKujk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=n821X1d07vJ0M8NP3BZW0Ys8udRQ5yScEDf9aV1i6o3wJAww1l2vB7UrP99XCM1sJ 77P7jvbwzDtxf2rHOYn94Ulyi6CUgmq1jr+Bn907YFC6lvMSTqnmLz8Aeo9Kgbo1TH 3XSOP16QNzBil2XJvo5Ce3TPWYCOej3wRRlFEcL0= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ming Lei , Christoph Hellwig , "Ewan D . Milne" , Hannes Reinecke , Bart Van Assche , Lee Duncan , "Martin K . Petersen" , Sasha Levin , linux-scsi@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 07/11] scsi: core: Don't start concurrent async scan on same host Date: Mon, 2 Nov 2020 20:20:35 -0500 Message-Id: <20201103012039.183672-7-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201103012039.183672-1-sashal@kernel.org> References: <20201103012039.183672-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ming Lei [ Upstream commit 831e3405c2a344018a18fcc2665acc5a38c3a707 ] The current scanning mechanism is supposed to fall back to a synchronous host scan if an asynchronous scan is in progress. However, this rule isn't strictly respected, scsi_prep_async_scan() doesn't hold scan_mutex when checking shost->async_scan. When scsi_scan_host() is called concurrently, two async scans on same host can be started and a hang in do_scan_async() is observed. Fixes this issue by checking & setting shost->async_scan atomically with shost->scan_mutex. Link: https://lore.kernel.org/r/20201010032539.426615-1-ming.lei@redhat.com Cc: Christoph Hellwig Cc: Ewan D. Milne Cc: Hannes Reinecke Cc: Bart Van Assche Reviewed-by: Lee Duncan Reviewed-by: Bart Van Assche Signed-off-by: Ming Lei Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- drivers/scsi/scsi_scan.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 9a7e3a3bd5ce8..009a5b2aa3d02 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1722,15 +1722,16 @@ static void scsi_sysfs_add_devices(struct Scsi_Host *shost) */ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) { - struct async_scan_data *data; + struct async_scan_data *data = NULL; unsigned long flags; if (strncmp(scsi_scan_type, "sync", 4) == 0) return NULL; + mutex_lock(&shost->scan_mutex); if (shost->async_scan) { shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__); - return NULL; + goto err; } data = kmalloc(sizeof(*data), GFP_KERNEL); @@ -1741,7 +1742,6 @@ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) goto err; init_completion(&data->prev_finished); - mutex_lock(&shost->scan_mutex); spin_lock_irqsave(shost->host_lock, flags); shost->async_scan = 1; spin_unlock_irqrestore(shost->host_lock, flags); @@ -1756,6 +1756,7 @@ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) return data; err: + mutex_unlock(&shost->scan_mutex); kfree(data); return NULL; } -- 2.27.0