From: Joe Perches <joe@perches.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Chenggang Wang <wangchenggang@vivo.com>,
linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC PATCH 2/2] init: Allow multi-line output of kernel command line
Date: Tue, 19 May 2020 21:58:53 -0700 [thread overview]
Message-ID: <ae3aff79301c130aa15b3fe0ff801804bb019384.camel@perches.com> (raw)
In-Reply-To: <20200520044127.GB938@jagdpanzerIV.localdomain>
On Wed, 2020-05-20 at 13:41 +0900, Sergey Senozhatsky wrote:
> On (20/05/19 12:42), Joe Perches wrote:
> > +static void __init print_cmdline(char *line)
> > +{
> > +#ifdef CONFIG_PRINTK
> > + const char *prefix = "Kernel command line";
> > + size_t len = strlen(line);
> > +
> > + while (len > PRINTK_LOG_LINE_MAX) {
> > + char *pos = line;
> > + char *last_pos = pos + PRINTK_LOG_LINE_MAX - 1;
> > + char saved_char;
> > + /* Find last space char within the maximum line length */
> > + while ((pos = memchr(pos, ' ', len - (pos - line))) &&
> > + (pos - line) < PRINTK_LOG_LINE_MAX - 1) {
>
> Don't you need to also count in the 'prefix' length?
yup.
> > + last_pos = pos;
> > + }
> > + saved_char = line[last_pos - line];
> > + line[last_pos - line] = 0;
> > + pr_notice("%s: %s\n", prefix, line);
> > + prefix = "Kernel command line (continued)";
> > + line[last_pos - line] = saved_char;
> > + len -= pos - line;
> > + line += pos - line;
> > + }
> > +
> > + pr_notice("%s: %s\n", prefix, line);
> > +#endif
> > +}
>
> I like this in general. And I agree that we better handle this
> externally, on the printk() caller side, so that printk() will
> still have sane limits and won't print a 1G string for example.
>
> I wonder if we need to export PRINTK_LOG_LINE_MAX.
I think a #define works well enough.(
> Maybe we can
> use here something rather random and much shorter instead. E.g.
> 256 chars. Hmm. How
min(some_max like 132/256, PRINTK_LOG_LINE_MAX)
would work.
> many crash/monitoring tools can get confused
> by multiple "Kernel command line" prefixes?
I doubt any as it's an init only function.
next prev parent reply other threads:[~2020-05-20 4:58 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 3:29 [PATCH] init/main.c: Print all command line when boot 王程刚
2020-05-19 3:44 ` Andrew Morton
2020-05-19 5:09 ` Joe Perches
2020-05-19 14:34 ` Arvind Sankar
2020-05-19 19:42 ` [RFC PATCH 0/2] printk/init: multi-line kernel command line logging Joe Perches
2020-05-19 19:42 ` [RFC PATCH 1/2] printk: Move and rename maximum printk output line length defines Joe Perches
2020-05-21 13:49 ` Petr Mladek
2020-05-19 19:42 ` [RFC PATCH 2/2] init: Allow multi-line output of kernel command line Joe Perches
2020-05-20 4:41 ` Sergey Senozhatsky
2020-05-20 4:58 ` Joe Perches [this message]
2020-05-20 12:10 ` Sergey Senozhatsky
2020-05-20 20:36 ` Joe Perches
2020-05-21 1:00 ` Andrew Morton
2020-05-21 2:09 ` Joe Perches
2020-05-21 4:36 ` Sergey Senozhatsky
2020-05-21 4:40 ` Andrew Morton
2020-05-21 12:31 ` Petr Mladek
2020-05-21 15:08 ` Arvind Sankar
2020-05-21 12:48 ` Sergey Senozhatsky
2020-05-21 4:32 ` Sergey Senozhatsky
2020-05-21 13:46 ` Petr Mladek
2020-05-21 15:59 ` Arvind Sankar
2020-05-21 16:09 ` Joe Perches
2020-06-03 8:48 ` [init] d0bcc26c0d: BUG:kernel_hang_in_early-boot_stage,last_printk:early_console_in_setup_code kernel test robot
2020-05-21 18:40 ` [PATCH] printk: Move and rename maximum printk output line length defines Joe Perches
2020-05-25 8:38 ` Sergey Senozhatsky
2020-05-20 14:01 ` [PATCH] init/main.c: Print all command line when boot Masami Hiramatsu
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