From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752995AbdDJSAm (ORCPT ); Mon, 10 Apr 2017 14:00:42 -0400 Received: from mail-lf0-f52.google.com ([209.85.215.52]:33997 "EHLO mail-lf0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752205AbdDJSAk (ORCPT ); Mon, 10 Apr 2017 14:00:40 -0400 Subject: Re: [PATCH v9 3/3] printk: fix double printing with earlycon To: Petr Mladek Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Sudeep Holla , Greg Kroah-Hartman , Peter Hurley , Jiri Slaby , Robin Murphy , Steven Rostedt , "Nair, Jayachandran" , Sergey Senozhatsky References: <20170315102854.1763-1-aleksey.makarov@linaro.org> <20170405202006.18234-1-aleksey.makarov@linaro.org> <20170410142214.GA3452@pathway.suse.cz> From: Aleksey Makarov Message-ID: <0514db53-4f8b-fa08-f461-902de85777ee@linaro.org> Date: Mon, 10 Apr 2017 21:00:35 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.0 MIME-Version: 1.0 In-Reply-To: <20170410142214.GA3452@pathway.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/10/2017 05:22 PM, Petr Mladek wrote: > On Wed 2017-04-05 23:20:00, Aleksey Makarov wrote: >> 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 > > This version looks fine to me. Just a small nitpick below. > Anyway: > > Reviewed-by: Petr Mladek Thank you for review. Can you (or anybody else) ACK it? I am going to resend the whole series without those empty lines. May I add your Acked-by:? Thank you Aleksey Makarov >> 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; >> + > > This extra new line is non-standard and looks slightly weird to me. > I just point it out. I personally do not mind ;-) > > >> + 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; >> } >> } >> @@ -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--) { >> + > > Same here. > >> + c = console_cmdline + i; >> + >> if (!newcon->match || >> newcon->match(newcon, c->name, c->index, c->options) != 0) { >> /* default matching */ > > Best Regards, > Petr >