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=ham 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 CA535C388F7 for ; Mon, 9 Nov 2020 13:36:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7737D206B2 for ; Mon, 9 Nov 2020 13:36:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604928999; bh=SCX2Bvt7RIbKtlNwma4O1ggwwDDo9Fw7byanKlpDy2E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=RVfBl9f7JbXoTELzL0a92cTzwOno91H29whU4znbZItACeEuFtnZtG+xgC3BQ9PyH ukLNbZaQQatwHHLTfzA/Lso3fcCXw8qS+qs97HiFqmsPd2aSi9NUPAN7sBwYmPAUsj lGYE09z24vvDwmb12DKMJ/uBCvf6TDiEQSd4kA6U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732292AbgKINg2 (ORCPT ); Mon, 9 Nov 2020 08:36:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:57668 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729661AbgKINEp (ORCPT ); Mon, 9 Nov 2020 08:04:45 -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 79D8F20663; Mon, 9 Nov 2020 13:04:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927085; bh=SCX2Bvt7RIbKtlNwma4O1ggwwDDo9Fw7byanKlpDy2E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ds8ATcy1wa7G5IPRuADtBrAPTmgMLuMx4q5Wphjq4iWgyfbCI+uRbN6WHEczrTFRp AT7CI/8CHkyTRForw4GooTn2rUhQSSAseHrERrMQDVlrw25XG/+fEDhD748kMzTHva OACxblIBlq5BlZIcKl40v8itGRhmVqVYjk7qt6LA= 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 4.9 105/117] scsi: core: Dont start concurrent async scan on same host Date: Mon, 9 Nov 2020 13:55:31 +0100 Message-Id: <20201109125030.680000430@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125025.630721781@linuxfoundation.org> References: <20201109125025.630721781@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 67f6f134abc44..397deb69c6595 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1734,15 +1734,16 @@ 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); @@ -1753,7 +1754,6 @@ 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); @@ -1768,6 +1768,7 @@ 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