From patchwork Sun Apr 23 08:24:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mirsad Todorovac X-Patchwork-Id: 13221233 X-Patchwork-Delegate: johannes@sipsolutions.net 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 4E2BDC77B73 for ; Sun, 23 Apr 2023 08:40:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229774AbjDWIkb (ORCPT ); Sun, 23 Apr 2023 04:40:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbjDWIka (ORCPT ); Sun, 23 Apr 2023 04:40:30 -0400 Received: from domac.alu.hr (domac.alu.unizg.hr [161.53.235.3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5A6D1BC2; Sun, 23 Apr 2023 01:40:28 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by domac.alu.hr (Postfix) with ESMTP id CD7696015E; Sun, 23 Apr 2023 10:40:24 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=alu.unizg.hr; s=mail; t=1682239225; bh=NrrlTJuO2WOxeh84ut/e47TmcJC+8c5WzWqQwG1PyZM=; h=From:To:Cc:Subject:Date:From; b=wGp+Td+o+UT/S6x13KMiwr0evq+FpgQ35SnO8axIUu1KndCG36ab4g5H1X4Epe3X5 6iOrEGvFXGj9f7rf24cu1DQAZILmvknxsGVUI0Zxlc14EjNvaGVEWorFC9toty2Ptq EwE8KW2hnmkpIYqu1n+HTfz5YeyvhvOCE1UCzuPxH3/SvbKzCao5yTWqJbJ3OqoVOE ta1429MrqTlEilYvh5OCUJWYispnfe8OKkB/ZALFSRhdXiPWTBGzma4uoS+VheP5/j pu0wqE0xul5MA3/5vJ14wr3Hc//4rURDTsgGsiwM6bl24cooj3dRi/yQ1ZhflHlH2v DMUTbw9U2/6cA== X-Virus-Scanned: Debian amavisd-new at domac.alu.hr Received: from domac.alu.hr ([127.0.0.1]) by localhost (domac.alu.hr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 2RCTnkPxMSfa; Sun, 23 Apr 2023 10:40:22 +0200 (CEST) Received: by domac.alu.hr (Postfix, from userid 1014) id 3B93C6015F; Sun, 23 Apr 2023 10:40:22 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=alu.unizg.hr; s=mail; t=1682239222; bh=NrrlTJuO2WOxeh84ut/e47TmcJC+8c5WzWqQwG1PyZM=; h=From:To:Cc:Subject:Date:From; b=h6uu9H21cv/CQb7i/w6iaZiCtnHDd6k/JZ+kg3zkyo1LktTCzrRay48eAqqhjYPQ6 RAQf+ap1wI8HeWv8va3hg/gja8U0bd+SpzUc1mwbr36D1q4DO51T7VG9qNA74jzASw k7FpCRsZYQEMzpAwLz8Asf/vIGPtUvKOxOUPLZJUtqdxQ7KjzNbOlgf7eREPpR6ntb Flg8d1UDCPNnoh2bVgZzp4cwO0KLOUaNFb30Cp6iwKZffA0XPcvYAsOvBkDlNUDgCR DgEGflKgN0lXN0aY4Mt5Koh/SIFr6/FMc1SzHnfwBS/fJLDaW6X5PvgsITHiV7zJRB vvby6RT8r9xkQ== From: Mirsad Goran Todorovac To: Johannes Berg , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Johannes Berg , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Mirsad Goran Todorovac , Alexander Wetzel Subject: [PATCH RFC v1 1/1] net: mac80211: fortify the spinlock against deadlock in interrupt Date: Sun, 23 Apr 2023 10:24:05 +0200 Message-Id: <20230423082403.49143-1-mirsad.todorovac@alu.unizg.hr> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org In the function ieee80211_tx_dequeue() there is a locking sequence: begin: spin_lock(&local->queue_stop_reason_lock); q_stopped = local->queue_stop_reasons[q]; spin_unlock(&local->queue_stop_reason_lock); However small the chance (increased by ftracetest), an asynchronous interrupt can occur in between of spin_lock() and spin_unlock(), and the interrupt routine will attempt to lock the same &local->queue_stop_reason_lock again. This is the only remaining spin_lock() on local->queue_stop_reason_lock that did not disable interrupts and could have possibly caused the deadlock on the same CPU (core). This will cause a costly reset of the CPU and wifi device or an altogether hang in the single CPU and single core scenario. This is the probable reproduce of the deadlock: Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: Possible unsafe locking scenario: Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: CPU0 Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: ---- Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: lock(&local->queue_stop_reason_lock); Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: lock(&local->queue_stop_reason_lock); Apr 10 00:58:33 marvin-IdeaPad-3-15ITL6 kernel: *** DEADLOCK *** Fixes: 4444bc2116ae Link: https://lore.kernel.org/all/1f58a0d1-d2b9-d851-73c3-93fcc607501c@alu.unizg.hr/ Cc: Alexander Wetzel Signed-off-by: Mirsad Goran Todorovac --- net/mac80211/tx.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 7699fb410670..45cb8e7bcc61 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -3781,6 +3781,7 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, ieee80211_tx_result r; struct ieee80211_vif *vif = txq->vif; int q = vif->hw_queue[txq->ac]; + unsigned long flags; bool q_stopped; WARN_ON_ONCE(softirq_count() == 0); @@ -3789,9 +3790,9 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, return NULL; begin: - spin_lock(&local->queue_stop_reason_lock); + spin_lock_irqsave(&local->queue_stop_reason_lock, flags); q_stopped = local->queue_stop_reasons[q]; - spin_unlock(&local->queue_stop_reason_lock); + spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags); if (unlikely(q_stopped)) { /* mark for waking later */