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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9BBEEC433E9 for ; Thu, 18 Feb 2021 09:40:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57ED964D99 for ; Thu, 18 Feb 2021 09:40:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231970AbhBRJbZ (ORCPT ); Thu, 18 Feb 2021 04:31:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230125AbhBRITr (ORCPT ); Thu, 18 Feb 2021 03:19:47 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2013EC061797 for ; Thu, 18 Feb 2021 00:18:26 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1613636302; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kc+0CbVZpOG9vn6O/gIVFLqAy93zyrZ18F7TF9AbwSY=; b=gEkReXYg1sRyPYtR5Y8SG/zMk7EMILAGB17Xc4yzDL4vvapjJ6l+FX41TZtsxOTWJ9PuAz apz5yWsj2WFa6Pvkl87x/ZDsHFqor5KFLhEdZq1qS/O75GUCb+CV5U39Nv5yag9Ivyen3m /47dfT6H9RRaMqsz84r/PZsSNXqFsz6J0bEOllGB17Pbu1S8GJXGGhTE0pNfQ8Oji0fNn4 wm12PlMyrSBRbHb2tBIqmnuYOpZg7Rg3qubefo9XllnbrH5AlMW/+xPqHs5/LuiVeCMN74 n+dB8n3Vz3d9OgW/OMuPp8hxtcP1K/0bYD1N/Sh4sGSnu/GAJkWfBvTE9BClPA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1613636302; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kc+0CbVZpOG9vn6O/gIVFLqAy93zyrZ18F7TF9AbwSY=; b=Fk2Hbs+zb13O+FshiJj8DI1lXIiEtt0Yhqq4jxjDfVfbvS2nUeA5td3fR4cNiFtTW7H/iM xBZVNe7tzZ4iZWCg== To: Petr Mladek Cc: Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Richard Weinberger Subject: [PATCH printk-rework 10/14] um: synchronize kmsg_dumper Date: Thu, 18 Feb 2021 09:18:13 +0100 Message-Id: <20210218081817.28849-11-john.ogness@linutronix.de> In-Reply-To: <20210218081817.28849-1-john.ogness@linutronix.de> References: <20210218081817.28849-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kmsg_dumper can be called from any context and CPU, possibly from multiple CPUs simultaneously. Since a static buffer is used to retrieve the kernel logs, this buffer must be protected against simultaneous dumping. Cc: Richard Weinberger Signed-off-by: John Ogness Reviewed-by: Petr Mladek --- arch/um/kernel/kmsg_dump.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c index f38349ad00ea..173999422ed8 100644 --- a/arch/um/kernel/kmsg_dump.c +++ b/arch/um/kernel/kmsg_dump.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include #include @@ -9,8 +10,10 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason, struct kmsg_dumper_iter *iter) { + static DEFINE_SPINLOCK(lock); static char line[1024]; struct console *con; + unsigned long flags; size_t len = 0; /* only dump kmsg when no console is available */ @@ -25,11 +28,16 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper, if (con) return; + if (!spin_trylock_irqsave(&lock, flags)) + return; + printf("kmsg_dump:\n"); while (kmsg_dump_get_line(iter, true, line, sizeof(line), &len)) { line[len] = '\0'; printf("%s", line); } + + spin_unlock_irqrestore(&lock, flags); } static struct kmsg_dumper kmsg_dumper = { -- 2.20.1