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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D1D8C433EF for ; Tue, 26 Apr 2022 19:03:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354001AbiDZTGo (ORCPT ); Tue, 26 Apr 2022 15:06:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353865AbiDZTGL (ORCPT ); Tue, 26 Apr 2022 15:06:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB12519ADAE; Tue, 26 Apr 2022 12:02:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 66E40619BA; Tue, 26 Apr 2022 19:02:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AADA6C385A0; Tue, 26 Apr 2022 19:02:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1650999775; bh=V8YUgaezTT2Bmh9ZPpBjU6t2I/wCUUmu7gMVP/8UlnY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pux6l/DKgYOTB03pI3NpyyNit+/E6evd4+2faSCtkUeq7WqosORQiIKRxc1O+qIeN 5HkmHWu6EJCnMDpxglZ+cKk51gLZKEINVgffADET+vV0uzm9BSsOuXnM+kVvnPntB4 2Sgz+W74F0v9HKBbQO4j3hxLPxmdMMtOqmQPo9lU2/BaCdsa3C7Iq3acwQJ7KcwEq8 jX52qMCdBtupV6+KklR+e3YlVfbqySS6Ty+kISaCU6tIHi51MjqXhqdaU3m47Zqjr8 jI1LTBy3JMiGgVKn+XIvD3ChuVHPRu5Bs3aKHiKqmohhfqZQ9WocPCegMH5WgBE4Mi qxBHsEOVBCsCQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Duoming Zhou , Paolo Abeni , Sasha Levin , jes@trained-monkey.org, davem@davemloft.net, kuba@kernel.org, linux-hippi@sunsite.dk, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 5/6] drivers: net: hippi: Fix deadlock in rr_close() Date: Tue, 26 Apr 2022 15:02:48 -0400 Message-Id: <20220426190251.2351817-5-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220426190251.2351817-1-sashal@kernel.org> References: <20220426190251.2351817-1-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: netdev@vger.kernel.org From: Duoming Zhou [ Upstream commit bc6de2878429e85c1f1afaa566f7b5abb2243eef ] There is a deadlock in rr_close(), which is shown below: (Thread 1) | (Thread 2) | rr_open() rr_close() | add_timer() spin_lock_irqsave() //(1) | (wait a time) ... | rr_timer() del_timer_sync() | spin_lock_irqsave() //(2) (wait timer to stop) | ... We hold rrpriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need rrpriv->lock in position (2) of thread 2. As a result, rr_close() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_irqsave(), which could let timer handler to obtain the needed lock. Signed-off-by: Duoming Zhou Link: https://lore.kernel.org/r/20220417125519.82618-1-duoming@zju.edu.cn Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- drivers/net/hippi/rrunner.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/hippi/rrunner.c b/drivers/net/hippi/rrunner.c index 2a8c33abb363..a24c55a6c79a 100644 --- a/drivers/net/hippi/rrunner.c +++ b/drivers/net/hippi/rrunner.c @@ -1352,7 +1352,9 @@ static int rr_close(struct net_device *dev) rrpriv->fw_running = 0; + spin_unlock_irqrestore(&rrpriv->lock, flags); del_timer_sync(&rrpriv->timer); + spin_lock_irqsave(&rrpriv->lock, flags); writel(0, ®s->TxPi); writel(0, ®s->IpRxPi); -- 2.35.1