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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 E6A26C65C20 for ; Mon, 8 Oct 2018 18:33:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B342320C0A for ; Mon, 8 Oct 2018 18:33:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="kVgRZX18" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B342320C0A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726933AbeJIBqN (ORCPT ); Mon, 8 Oct 2018 21:46:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:56182 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726391AbeJIBqN (ORCPT ); Mon, 8 Oct 2018 21:46:13 -0400 Received: from localhost (ip-213-127-77-176.ip.prioritytelecom.net [213.127.77.176]) (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 B145F2089D; Mon, 8 Oct 2018 18:33:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1539023590; bh=vxvRQq3cD+axuUcFX7ss//OHiCmuIA/I+7r33TPi24Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kVgRZX18fz9LjVmsWbUu4nEXiVuVpfHM+Uo7LJuyMu2wozWzGdW4CdkGFygO3TAEf 5JWaYEcK1Fn7A0cWJFWjrjX3sQ/Sc9XH1h+JvX2B6oHIe4TNgAL0/3hnpNk4mtCw7d h3T91IV9kS++cIpNW9dR1pOIGemipCAbLyvzTOtY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bart Van Assche , "Martin K. Petersen" , James Bottomley , Sasha Levin Subject: [PATCH 4.4 018/113] scsi: klist: Make it safe to use klists in atomic context Date: Mon, 8 Oct 2018 20:30:19 +0200 Message-Id: <20181008175531.738764632@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20181008175530.864641368@linuxfoundation.org> References: <20181008175530.864641368@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bart Van Assche [ Upstream commit 624fa7790f80575a4ec28fbdb2034097dc18d051 ] In the scsi_transport_srp implementation it cannot be avoided to iterate over a klist from atomic context when using the legacy block layer instead of blk-mq. Hence this patch that makes it safe to use klists in atomic context. This patch avoids that lockdep reports the following: WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&k->k_lock)->rlock); local_irq_disable(); lock(&(&q->__queue_lock)->rlock); lock(&(&k->k_lock)->rlock); lock(&(&q->__queue_lock)->rlock); stack backtrace: Workqueue: kblockd blk_timeout_work Call Trace: dump_stack+0xa4/0xf5 check_usage+0x6e6/0x700 __lock_acquire+0x185d/0x1b50 lock_acquire+0xd2/0x260 _raw_spin_lock+0x32/0x50 klist_next+0x47/0x190 device_for_each_child+0x8e/0x100 srp_timed_out+0xaf/0x1d0 [scsi_transport_srp] scsi_times_out+0xd4/0x410 [scsi_mod] blk_rq_timed_out+0x36/0x70 blk_timeout_work+0x1b5/0x220 process_one_work+0x4fe/0xad0 worker_thread+0x63/0x5a0 kthread+0x1c1/0x1e0 ret_from_fork+0x24/0x30 See also commit c9ddf73476ff ("scsi: scsi_transport_srp: Fix shost to rport translation"). Signed-off-by: Bart Van Assche Cc: Martin K. Petersen Cc: James Bottomley Acked-by: Greg Kroah-Hartman Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- lib/klist.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/lib/klist.c +++ b/lib/klist.c @@ -336,8 +336,9 @@ struct klist_node *klist_prev(struct kli void (*put)(struct klist_node *) = i->i_klist->put; struct klist_node *last = i->i_cur; struct klist_node *prev; + unsigned long flags; - spin_lock(&i->i_klist->k_lock); + spin_lock_irqsave(&i->i_klist->k_lock, flags); if (last) { prev = to_klist_node(last->n_node.prev); @@ -356,7 +357,7 @@ struct klist_node *klist_prev(struct kli prev = to_klist_node(prev->n_node.prev); } - spin_unlock(&i->i_klist->k_lock); + spin_unlock_irqrestore(&i->i_klist->k_lock, flags); if (put && last) put(last); @@ -377,8 +378,9 @@ struct klist_node *klist_next(struct kli void (*put)(struct klist_node *) = i->i_klist->put; struct klist_node *last = i->i_cur; struct klist_node *next; + unsigned long flags; - spin_lock(&i->i_klist->k_lock); + spin_lock_irqsave(&i->i_klist->k_lock, flags); if (last) { next = to_klist_node(last->n_node.next); @@ -397,7 +399,7 @@ struct klist_node *klist_next(struct kli next = to_klist_node(next->n_node.next); } - spin_unlock(&i->i_klist->k_lock); + spin_unlock_irqrestore(&i->i_klist->k_lock, flags); if (put && last) put(last);