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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 D5E00C2D0A3 for ; Mon, 9 Nov 2020 12:59:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99C0B20684 for ; Mon, 9 Nov 2020 12:59:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604926759; bh=+DuDdVpjTF8qkkCWdGV1GlLIMkWVkV/LL5kQv0N/2Ig=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=llevrrpH6UFvNbU2sp5GZZykZO16751xEUWwbO/u09MWQQv16Y4hbsttnSB6I8xqR BiC0MomMrk1ou/JJ4m4xQhxmvCqjA1icXcqLTu+7/3vbcuuCRnDw4+po7S0qvR1K/4 KFm7ox2kcfQvNAtsvpexpFIPTtrawn4JbMwR6C4A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730311AbgKIM7S (ORCPT ); Mon, 9 Nov 2020 07:59:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:53296 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729853AbgKIM7G (ORCPT ); Mon, 9 Nov 2020 07:59:06 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0AC9720897; Mon, 9 Nov 2020 12:59:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604926745; bh=+DuDdVpjTF8qkkCWdGV1GlLIMkWVkV/LL5kQv0N/2Ig=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wpYzmqWSOJWtAD4l1qI02iPYu/6tPvw++Y3HInC6yR6s7cuJAygEE3JwOAiqK88R8 U1LvIgZOJbMSkN6T0p/dmPcaRm9l2p9dSR93r0GUIf2nFYZ7g9V/A/vCUfq8RaY4Do 9HJCBB+Z4o3eidNARPReN5lQqxKlqVB2l+soLJeo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christoph Hellwig , "Ewan D. Milne" , Hannes Reinecke , Bart Van Assche , Lee Duncan , Ming Lei , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 4.4 75/86] scsi: core: Dont start concurrent async scan on same host Date: Mon, 9 Nov 2020 13:55:22 +0100 Message-Id: <20201109125024.393473614@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125020.852643676@linuxfoundation.org> References: <20201109125020.852643676@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 3e2288af56bc3..647a057a9b6cc 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1710,15 +1710,16 @@ 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); @@ -1729,7 +1730,6 @@ 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); @@ -1744,6 +1744,7 @@ 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