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=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 B6457C10F12 for ; Tue, 16 Apr 2019 01:20:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7062A20854 for ; Tue, 16 Apr 2019 01:20:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YraGu5a0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728337AbfDPBUX (ORCPT ); Mon, 15 Apr 2019 21:20:23 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:35577 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726527AbfDPBUU (ORCPT ); Mon, 15 Apr 2019 21:20:20 -0400 Received: by mail-pf1-f193.google.com with SMTP id t21so9517378pfh.2; Mon, 15 Apr 2019 18:20:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=MfB1avXudyIW6ugF85fX9+AhvoJyhOP6GmQo/+b/zaw=; b=YraGu5a0rGf0WHR1VG7WZcHz57F5UWKxXVvvTwkbIYuMgUEYp/YosCisnnOpHBpsv4 zywx8QsaXJZgZOuTDwboj0mqeFy2tS3YxEBzYoj5UgUdESvaDCTchZEphVugzKWphey/ jNmXlO3Ptw4nNZ0x4EB0trccgyae4I2MJg7zsv3b7IfLbUsQoXaPPk2Gc40W3XZhc5kX 7PpAqaj0VO1TFATCR/2A9p7dT8HjyEx09lAz+5pvzheRSEVPNxO5wiefBXJ4cP+XtMG+ JiHqfub04Q31h8esDfkrUIXNWZiPtMe/ZXX80vaboy/ICdTaSqPysYSC24ZMXL36c3b/ eLhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=MfB1avXudyIW6ugF85fX9+AhvoJyhOP6GmQo/+b/zaw=; b=jTAUQVSweY61Erko0e9RKJBDMRIM+QIl6r2jini362emDVvC+bj781xLJ+7ofrDA+U NfaFBmQdn4n9JFvE23m7xU1K1zJUyNzT6J0DkPo7vtvplTvXaZPpsuAfsyOOMDNO0ZhE p6osL7OtSnQ68jBJGqMBHDmjZOELY0ZaTRpKIo5kBsrpB2cjRKbUKzKvtlaAB+wBAQga ugqGGvpR82zxkdrD0AIGo4RobRzAbLRoPa4fvf53fy4xZUppEIY9JfvWyXIm7TQIobWj xXvEyvFVM9X5x77VxWEQl80u3SpfbbcYhDQqLRfG2rXzrX62GLGwg76qSfpQ9zYgUqU0 +Vbg== X-Gm-Message-State: APjAAAXATJtBNspgI5VwbKVVa2R4Aj+r5TVo/NaV/MukjLzRBwlHzVwm 5wENoLGrSrjaxZsj9wXG3inlhAnj X-Google-Smtp-Source: APXvYqwCgVKQhfQc+0TsM81Po8JlbBbj5+CbuvgrjZuZwTDrb4jivDryI4UQGHdCabFFL+Hu82dejQ== X-Received: by 2002:aa7:8e0d:: with SMTP id c13mr42306778pfr.193.1555377619551; Mon, 15 Apr 2019 18:20:19 -0700 (PDT) Received: from tw-172-25-31-76.office.twttr.net ([8.25.197.24]) by smtp.gmail.com with ESMTPSA id a85sm64206995pfa.166.2019.04.15.18.20.17 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 15 Apr 2019 18:20:18 -0700 (PDT) From: Cong Wang To: linux-kernel@vger.kernel.org Cc: linux-edac@vger.kernel.org, Cong Wang , Tony Luck , Borislav Petkov , Thomas Gleixner Subject: [PATCH 2/2] ras: close the race condition with timer Date: Mon, 15 Apr 2019 18:20:01 -0700 Message-Id: <20190416012001.5338-2-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190416012001.5338-1-xiyou.wangcong@gmail.com> References: <20190416012001.5338-1-xiyou.wangcong@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cec_timer_fn() is a timer callback which reads ce_arr.array[] and updates its decay values. Elements could be added to or removed from this global array in parallel, although the array itself will not grow or shrink. del_lru_elem_unlocked() uses FULL_COUNT() as a key to find a right element to remove, which could be affected by the parallel timer. Fix this by converting the mutex to a spinlock and holding it inside the timer. Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector") Cc: Tony Luck Cc: Borislav Petkov Cc: Thomas Gleixner Signed-off-by: Cong Wang --- drivers/ras/cec.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c index 61332c9aab5a..a82c9d08d47a 100644 --- a/drivers/ras/cec.c +++ b/drivers/ras/cec.c @@ -117,7 +117,7 @@ static struct ce_array { }; } ce_arr; -static DEFINE_MUTEX(ce_mutex); +static DEFINE_SPINLOCK(ce_lock); static u64 dfs_pfn; /* Amount of errors after which we offline */ @@ -171,7 +171,9 @@ static void cec_mod_timer(struct timer_list *t, unsigned long interval) static void cec_timer_fn(struct timer_list *unused) { + spin_lock(&ce_lock); do_spring_cleaning(&ce_arr); + spin_unlock(&ce_lock); cec_mod_timer(&cec_timer, timer_interval); } @@ -265,9 +267,9 @@ static u64 __maybe_unused del_lru_elem(void) if (!ca->n) return 0; - mutex_lock(&ce_mutex); + spin_lock_bh(&ce_lock); pfn = del_lru_elem_unlocked(ca); - mutex_unlock(&ce_mutex); + spin_unlock_bh(&ce_lock); return pfn; } @@ -288,7 +290,7 @@ int cec_add_elem(u64 pfn) ca->ces_entered++; - mutex_lock(&ce_mutex); + spin_lock_bh(&ce_lock); if (ca->n == MAX_ELEMS) WARN_ON(!del_lru_elem_unlocked(ca)); @@ -349,7 +351,7 @@ int cec_add_elem(u64 pfn) do_spring_cleaning(ca); unlock: - mutex_unlock(&ce_mutex); + spin_unlock_bh(&ce_lock); return ret; } @@ -406,7 +408,7 @@ static int array_dump(struct seq_file *m, void *v) u64 prev = 0; int i; - mutex_lock(&ce_mutex); + spin_lock_bh(&ce_lock); seq_printf(m, "{ n: %d\n", ca->n); for (i = 0; i < ca->n; i++) { @@ -431,7 +433,7 @@ static int array_dump(struct seq_file *m, void *v) seq_printf(m, "Action threshold: %d\n", count_threshold); - mutex_unlock(&ce_mutex); + spin_unlock_bh(&ce_lock); return 0; } -- 2.20.1