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=-15.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,INVALID_DATE_TZ_ABSURD,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 ECCA5C4338F for ; Tue, 3 Aug 2021 13:13:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D239860EFD for ; Tue, 3 Aug 2021 13:13:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236446AbhHCNNq (ORCPT ); Tue, 3 Aug 2021 09:13:46 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:56292 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236324AbhHCNNU (ORCPT ); Tue, 3 Aug 2021 09:13:20 -0400 From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1627996387; 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=xAgt43961jyij8yurqAZzMzspZ62E9WGA/zMDz6s0Qw=; b=YpPWs3o/B08aeOu2jZY5CcU8eMJIzia50ZUSkZ/lljJApVZApvJvxFCjM9HD1tup/y6yD3 1mqq2hQTMEyZpivHFcbjLndetNDr01ZLTx51xYG8+DWxX4H6j+vENOSYsx73oK+qs8Xqm1 /y84n45T2NHu0gArNlLAt8xIw2rRITjlNumNhCKAzNtNtvn5f4v6uKgbYQ+7pzQ7ez1nkL IvBy4DpkFnJO9CKGfLwUQYCUyyTyDIkvuZpZ4NUknW3dus4t5g3/bJfPrCzrktDssURZNg Hh0Q2F+rnnFDJRwDtV3im5RWA1QFD/HjZqrFcdf71xi3Ao4siI4dKwEnloFksA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1627996387; 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=xAgt43961jyij8yurqAZzMzspZ62E9WGA/zMDz6s0Qw=; b=MCZ7OS/cK1rdoa45XNCSrdVh34SJf6UBPkwX7KPK88AHKgr7SUDhadj+wmCwcKhrWAa/DG 4JjP66cVvCzqf8DA== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Jason Wessel , Daniel Thompson , Douglas Anderson , Sumit Garg , Cengiz Can , kgdb-bugreport@lists.sourceforge.net Subject: [PATCH printk v1 09/10] kdb: if available, only use atomic consoles for output mirroring Date: Tue, 3 Aug 2021 15:19:00 +0206 Message-Id: <20210803131301.5588-10-john.ogness@linutronix.de> In-Reply-To: <20210803131301.5588-1-john.ogness@linutronix.de> References: <20210803131301.5588-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently kdb uses the @oops_in_progress hack to mirror kdb output to all active consoles from NMI context. Ignoring locks is unsafe. Now that an NMI-safe atomic interface is available for consoles, use only that interface to mirror kdb output if such a console is available. Signed-off-by: John Ogness --- kernel/debug/kdb/kdb_io.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index 6735ac36b718..871b89d6294b 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -544,6 +544,7 @@ static int kdb_search_string(char *searched, char *searchfor) static void kdb_msg_write(const char *msg, int msg_len) { + bool atomic_console_available; struct console *c; const char *cp; int len; @@ -559,11 +560,26 @@ static void kdb_msg_write(const char *msg, int msg_len) cp++; } + atomic_console_available = have_atomic_console(); + for_each_console(c) { if (!(c->flags & CON_ENABLED)) continue; if (c == dbg_io_ops->cons) continue; + + /* + * If any atomic consoles are available, only atomic + * consoles are used. + */ + if (atomic_console_available) { + if (c->write_atomic) { + c->write_atomic(c, msg, msg_len); + touch_nmi_watchdog(); + } + continue; + } + /* * Set oops_in_progress to encourage the console drivers to * disregard their internal spin locks: in the current calling -- 2.20.1