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 F11C7C43217 for ; Tue, 26 Apr 2022 19:03:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351686AbiDZTGv (ORCPT ); Tue, 26 Apr 2022 15:06:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353888AbiDZTGP (ORCPT ); Tue, 26 Apr 2022 15:06:15 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 051A91999C6; Tue, 26 Apr 2022 12:03:05 -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 ams.source.kernel.org (Postfix) with ESMTPS id A6C92B82250; Tue, 26 Apr 2022 19:03:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50567C385B3; Tue, 26 Apr 2022 19:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1650999782; bh=O726eevFd4aa9bv4B67BLbuQbMjvTTVMMcyh219BVxE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mopUpv9RaVceM87dOZlg+cy0dRZYR21ZRO8jsiyYnLOaa2kgIj/1pf0JbzOLNZMi8 VXSa02/JXo13AbrQPusaBd+msXXnsqXOlICuuY85Mi7AANrxffXB4Jm6iym7e2Bhoq p1xDUTXDRZZ6cRlB1EEqXvYJMA2GcSenN9tkQ7Dfoppu6Kj8iTP9t++CX4uCBYMhWs WhCTQ8llQYB0qrYW6nxFb/f6b4teVSQsS4ZHd92FZXA8HnxmgOPSaEhanteTFqcwtU Mzy1iLm6J7HS7U6QImcnV+m2+Y3qQfOJklIgzUpht5w2AENt50eJYBoMYdlpREcI8u kDwCLr9VmzmJA== 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 4.14 4/5] drivers: net: hippi: Fix deadlock in rr_close() Date: Tue, 26 Apr 2022 15:02:55 -0400 Message-Id: <20220426190258.2351902-4-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220426190258.2351902-1-sashal@kernel.org> References: <20220426190258.2351902-1-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: stable@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 40ef4aeb0ef0..3a73ac03fb2b 100644 --- a/drivers/net/hippi/rrunner.c +++ b/drivers/net/hippi/rrunner.c @@ -1354,7 +1354,9 @@ 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