From patchwork Wed Apr 5 20:20:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aleksey Makarov X-Patchwork-Id: 96904 Delivered-To: patch@linaro.org Received: by 10.140.89.233 with SMTP id v96csp431628qgd; Wed, 5 Apr 2017 13:20:45 -0700 (PDT) X-Received: by 10.84.169.36 with SMTP id g33mr38819226plb.36.1491423644932; Wed, 05 Apr 2017 13:20:44 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id j64si21478884pge.346.2017.04.05.13.20.44; Wed, 05 Apr 2017 13:20:44 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-serial-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@linaro.org; spf=pass (google.com: best guess record for domain of linux-serial-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-serial-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934075AbdDEUUg (ORCPT + 3 others); Wed, 5 Apr 2017 16:20:36 -0400 Received: from mail-lf0-f49.google.com ([209.85.215.49]:35101 "EHLO mail-lf0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934091AbdDEUUZ (ORCPT ); Wed, 5 Apr 2017 16:20:25 -0400 Received: by mail-lf0-f49.google.com with SMTP id j90so15988542lfk.2 for ; Wed, 05 Apr 2017 13:20:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=GVMqE2lqp+oyrh1zjIZ/EG8hyyeKm2MMxkub+N+sbS0=; b=kixEreOqrtegx/ssrzQzL8psLZ7W4vCO0Xcjn8A0zIZ+PZsvNU1Oz7ayi/pi2LKk2L PkbSFWrAKOhjdZ8ZRRYmgOnbja46Cb2Br00sEyIQ5iLBVtlmKs8QqLbKB5ZDKmeXYzvH pDTAYnXsx5JA/NkZPsT5pL4yZaiPc2BFCXyt0= 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; bh=GVMqE2lqp+oyrh1zjIZ/EG8hyyeKm2MMxkub+N+sbS0=; b=HClYKiTfnDgXi6NLqhjjmXI8z6RCcuDbVTUSLDLQO4MjqoHPTg1Q/52G7Ddi5GtG8p ZdyQFvLlofoN9RaAohVKyvgjdtP8st0QHclOHLs6+X6XTQkNkrX/Skv+homW2+AKOsD7 UUOGnQAzdtkslX7u/62z1SbVNnEFjL80bS2R8SvSzHdq9yB1Sa+bi2RvjmIwpV7Eb+tw M5+sTf/zV7JRkmMGmC8SR6BuOKG6i+NXuRQZF6L/0aOyWHAdHZVgWjBBjDSIsIaM0byO KwS/8OR5I1Hqrl76abJy3bd5MxZ68v7t6SsHSB4K6Y9yiKeTWjmyXh5DQ2cOl0NZ1gSI F7rg== X-Gm-Message-State: AFeK/H2oFwIW+ayMxinUgw0zJvddtYGOPLZXsdnZV6BHfRXWix3/yqQlCjQubfq8luTxdH3N X-Received: by 10.25.160.1 with SMTP id j1mr10620430lfe.44.1491423623852; Wed, 05 Apr 2017 13:20:23 -0700 (PDT) Received: from localhost.localdomain ([77.232.10.184]) by smtp.gmail.com with ESMTPSA id 30sm3878771ljv.62.2017.04.05.13.20.22 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Apr 2017 13:20:22 -0700 (PDT) From: Aleksey Makarov To: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Aleksey Makarov , Sudeep Holla , Greg Kroah-Hartman , Peter Hurley , Jiri Slaby , Robin Murphy , Steven Rostedt , "Nair, Jayachandran" , Sergey Senozhatsky , Petr Mladek Subject: [PATCH v9 3/3] printk: fix double printing with earlycon Date: Wed, 5 Apr 2017 23:20:00 +0300 Message-Id: <20170405202006.18234-1-aleksey.makarov@linaro.org> X-Mailer: git-send-email 2.12.1 In-Reply-To: <20170315102854.1763-1-aleksey.makarov@linaro.org> References: <20170315102854.1763-1-aleksey.makarov@linaro.org> Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org If a console was specified by ACPI SPCR table _and_ command line parameters like "console=ttyAMA0" _and_ "earlycon" were specified, then log messages appear twice. The root cause is that the code traverses the list of specified consoles (the `console_cmdline` array) and stops at the first match. But it may happen that the same console is referred by the elements of this array twice: pl011,mmio,0x87e024000000,115200 -- from SPCR ttyAMA0 -- from command line but in this case `preferred_console` points to the second entry and the flag CON_CONSDEV is not set, so bootconsole is not deregistered. To fix that, introduce an invariant "The last non-braille console is always the preferred one" on the entries of the console_cmdline array. Then traverse it in reverse order to be sure that if the console is preferred then it will be the first matching entry. Introduce variable console_cmdline_cnt that keeps the number of elements of the console_cmdline array (Petr Mladek). It helps to get rid of the loop that searches for the end of this array. Reported-by: Sudeep Holla Signed-off-by: Aleksey Makarov --- v8 -> v9: - Introduce variable console_cmdline_cnt that keeps the number of elements of the console_cmdline array (Petr Mladek). It helps to get rid of the loop that searches for the end of this array. For the record: I think that this console_cmdline_cnt implementation is worse than just a loop that finds the end of the array because 1) we have to support consistency between console_cmdline_cnt and console_cmdline_cnt 2) it makes patch a bit more intrusive v7 -> v8: - add an explanation to the comment how console_cmdline can contain entries referring to the same console - move the body of the function introduced in the previous version to cycle - don't panic() (Sergey Senozhatsky). Don't check this condition because the loop condition guarantees that it holds. - use swap() (Sergey Senozhatsky) v6 -> v7: - return back to v5 - leave the check for already registered entries and add a function that maintains the invariant. v5 -> v6: - drop v5 and continue to work on v4: - introduce _braille_is_braille_console(). It helps to split original loop into three parts: 1) search for braille console, 2) check for preferred_console, 3) match other entries so that these three parts do not intersect. - introduce for_each_console_cmdline() macros to traverse console_cmdline (Petr Mladek) kernel/printk/printk.c | 48 ++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 38 insertions(+), 10 deletions(-) -- 2.12.1 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Reviewed-by: Petr Mladek Acked-by: Sergey Senozhatsky Acked-by: Sergey Senozhatsky diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fd752f0c8ef1..be657af45758 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -269,6 +269,7 @@ static struct console *exclusive_console; #define MAX_CMDLINECONSOLES 8 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; +static int console_cmdline_cnt; static int preferred_console = -1; int console_set_on_cmdline; @@ -1905,12 +1906,26 @@ static int __add_preferred_console(char *name, int idx, char *options, * See if this tty is not yet registered, and * if we have a slot free. */ - for (i = 0, c = console_cmdline; - i < MAX_CMDLINECONSOLES && c->name[0]; - i++, c++) { + for (i = 0, c = console_cmdline; i < console_cmdline_cnt; i++, c++) { if (strcmp(c->name, name) == 0 && c->index == idx) { - if (!brl_options) - preferred_console = i; + + if (brl_options) + return 0; + + /* + * Maintain an invariant that will help to find if + * the matching console is preferred, see + * register_console(): + * + * The last non-braille console is always + * the preferred one. + */ + if (i != console_cmdline_cnt - 1) + swap(console_cmdline[i], + console_cmdline[console_cmdline_cnt - 1]); + + preferred_console = console_cmdline_cnt - 1; + return 0; } } @@ -1923,6 +1938,7 @@ static int __add_preferred_console(char *name, int idx, char *options, braille_set_options(c, brl_options); c->index = idx; + console_cmdline_cnt++; return 0; } /* @@ -2457,12 +2473,24 @@ void register_console(struct console *newcon) } /* - * See if this console matches one we selected on - * the command line. + * See if this console matches one we selected on the command line. + * + * There may be several entries in the console_cmdline array matching + * with the same console, one with newcon->match(), another by + * name/index: + * + * pl011,mmio,0x87e024000000,115200 -- added from SPCR + * ttyAMA0 -- added from command line + * + * Traverse the console_cmdline array in reverse order to be + * sure that if this console is preferred then it will be the first + * matching entry. We use the invariant that is maintained in + * __add_preferred_console(). */ - for (i = 0, c = console_cmdline; - i < MAX_CMDLINECONSOLES && c->name[0]; - i++, c++) { + for (i = console_cmdline_cnt - 1; i >= 0; i--) { + + c = console_cmdline + i; + if (!newcon->match || newcon->match(newcon, c->name, c->index, c->options) != 0) { /* default matching */