LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Potapenko <glider@google.com>,
	Dmitriy Vyukov <dvyukov@google.com>,
	kbuild test robot <fengguang.wu@intel.com>,
	syzkaller <syzkaller@googlegroups.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [PATCH] printk: inject caller information into the body of message
Date: Fri, 14 Sep 2018 19:37:21 +0900
Message-ID: <49d22738-17ad-410a-be0a-d27d76ba9f37@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20180914065728.GA515@jagdpanzerIV>

On 2018/09/14 15:57, Sergey Senozhatsky wrote:
> On (09/13/18 23:28), Sergey Senozhatsky wrote:
>> Not that I see any problems with pr_line_flush(). But can drop it, sure.
>> pr_line() is a replacement for pr_cont() and as such it's not for multi-line
>> buffering.
> 
> OK, attached.
> Let me know if anything needs to improved (including broken English).
> Will we keep in the printk tree or shall I send a formal patch to Andrew?



> @@ -20,6 +20,9 @@
>   * Annotation for a "continued" line of log printout (only done after a
>   * line that had no enclosing \n). Only to be used by core/arch code
>   * during early bootup (a continued line is not SMP-safe otherwise).
> + *
> + * Please consider pr_line()/vpr_line() functions for SMP-safe continued
> + * line printing.

I think the advantage is not limited to SMP-safeness. Reducing the frequency of
calling printk() will reduce overhead. Also, latency for netconsole will be
reduced by sending a whole line in one printk().



> +/**
> + * DEFINE_PR_LINE - define a new pr_line variable
> + * @lev:	printk() log level
> + * @name:	variable name
> + *
> + * Defines a new pr_line varialbe, which would use an implicit

s/varialbe/variable/ .

> + * stack buffer of size __PR_LINE_BUF_SZ.
> + */
> +#define DEFINE_PR_LINE(lev, name)				\
> +	char		__line_##name[__PR_LINE_BUF_SZ];	\
> +	struct pr_line	name = {				\
> +		.sb	= __SEQ_BUF_INITIALIZER(__line_##name,	\
> +					__PR_LINE_BUF_SZ),	\
> +		.level	= lev,					\
> +	}

Want a note that

  static DEFINE_PR_LINE(lev, name);

won't make "name" variable "static" ?



> +/**
> + * DEFINE_PR_LINE_BUF - define a new pr_line variable
> + * @lev:	printk() log level
> + * @name:	variable name
> + * @buf:	external buffer
> + * @sz:	external buffer size
> + *
> + * Defines a new pr_line variable, which would use an external
> + * buffer for printk line.
> + */
> +#define DEFINE_PR_LINE_BUF(lev, name, buf, sz)			\
> +	struct pr_line	name = {				\
> +		.sb	= __SEQ_BUF_INITIALIZER(buf, (sz)),	\
> +		.level	= lev,					\
> +	}
> +

I would use this one for the OOM killer. 80 bytes is too short.

  static char oom_print_buf[1024];
  DEFINE_PR_LINE_BUF(level, oom_print_buf);



> @@ -131,4 +187,8 @@ extern int
>  seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
>  #endif
>  
> +extern __printf(2, 0)
> +int vpr_line(struct pr_line *pl, const char *fmt, va_list args);
> +extern __printf(2, 3)
> +int pr_line(struct pr_line *pl, const char *fmt, ...);

Do we want to mark "asmlinkage" like printk() ?

> @@ -324,3 +324,60 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
>  	s->readpos += cnt;
>  	return cnt;
>  }
> +
> +/**
> + * vpr_line - Append data to the printk() line buffer
> + * @pl: the pr_line descriptor

s/descriptor/structure/ ?

> + * @fmt: printf format string
> + * @args: va_list of arguments from a printf() type function
> + *
> + * Writes a vnprintf() format into the printk() pr_line buffer.

s/vnprintf/vprintf/ ?


  reply index

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <201804232233.CIC65675.OJSOMFQOFFHVtL@I-love.SAKURA.ne.jp>
     [not found] ` <CACT4Y+boyw_Qy=y-iTnsKZrtTgF0Hk3nHN_xtqUdX4etgiYDQw@mail.gmail.com>
2018-04-24  1:33   ` printk feature for syzbot? Sergey Senozhatsky
2018-04-24 14:40     ` Steven Rostedt
2018-04-26 10:06     ` Petr Mladek
2018-05-10  4:22       ` Sergey Senozhatsky
2018-05-10 11:30         ` Petr Mladek
2018-05-10 12:11           ` Sergey Senozhatsky
2018-05-10 14:22             ` Steven Rostedt
2018-05-10 14:50         ` Tetsuo Handa
2018-05-11  1:45           ` Sergey Senozhatsky
     [not found]             ` <201805110238.w4B2cIGH079602@www262.sakura.ne.jp>
2018-05-11  6:21               ` Sergey Senozhatsky
2018-05-11  9:17                 ` Dmitry Vyukov
2018-05-11  9:50                   ` Sergey Senozhatsky
2018-05-11 11:58                     ` [PATCH] printk: inject caller information into the body of message Tetsuo Handa
2018-05-17 11:21                       ` Sergey Senozhatsky
2018-05-17 11:52                         ` Sergey Senozhatsky
2018-05-18 12:15                         ` Petr Mladek
2018-05-18 12:25                           ` Dmitry Vyukov
2018-05-18 12:54                             ` Petr Mladek
2018-05-18 13:08                               ` Dmitry Vyukov
2018-05-24  2:21                                 ` Sergey Senozhatsky
2018-05-23 10:19                           ` Tetsuo Handa
2018-05-24  2:14                           ` Sergey Senozhatsky
2018-05-26  6:36                             ` Dmitry Vyukov
2018-06-20  5:44                               ` Dmitry Vyukov
2018-06-20  8:31                                 ` Sergey Senozhatsky
2018-06-20  8:45                                   ` Dmitry Vyukov
2018-06-20  9:06                                     ` Sergey Senozhatsky
2018-06-20  9:18                                       ` Sergey Senozhatsky
2018-06-20  9:31                                         ` Dmitry Vyukov
2018-06-20 11:07                                           ` Sergey Senozhatsky
2018-06-20 11:32                                             ` Dmitry Vyukov
2018-06-20 13:06                                               ` Sergey Senozhatsky
2018-06-22 13:06                                                 ` Tetsuo Handa
2018-06-25  1:41                                                   ` Sergey Senozhatsky
2018-06-25  9:36                                                     ` Dmitry Vyukov
2018-06-27 10:29                                                       ` Tetsuo Handa
2018-09-10 11:20                                                 ` Alexander Potapenko
2018-09-12  6:53                                                   ` Sergey Senozhatsky
2018-09-12 16:05                                                     ` Steven Rostedt
2018-09-13  7:12                                                       ` Sergey Senozhatsky
2018-09-13 12:26                                                         ` Petr Mladek
2018-09-13 14:28                                                           ` Sergey Senozhatsky
2018-09-14  1:22                                                             ` Steven Rostedt
2018-09-14  2:15                                                               ` Sergey Senozhatsky
2018-09-14  6:57                                                             ` Sergey Senozhatsky
2018-09-14 10:37                                                               ` Tetsuo Handa [this message]
2018-09-14 11:50                                                                 ` Sergey Senozhatsky
2018-09-14 12:03                                                                   ` Tetsuo Handa
2018-09-14 12:22                                                                     ` Sergey Senozhatsky
2018-09-19 11:02                                                                       ` Tetsuo Handa
2018-09-24  8:11                                                                         ` Tetsuo Handa
2018-09-27 16:10                                                                           ` Tetsuo Handa
2018-09-28  9:02                                                                             ` Sergey Senozhatsky
2018-09-28  9:09                                                                           ` Sergey Senozhatsky
2018-09-28 11:01                                                                             ` Tetsuo Handa
2018-09-29 10:51                                                                               ` Sergey Senozhatsky
2018-09-29 11:15                                                                                 ` Tetsuo Handa
2018-10-01  2:37                                                                                   ` Sergey Senozhatsky
2018-10-01  2:58                                                                                     ` Sergey Senozhatsky
2018-10-01 11:21                                                                                     ` Tetsuo Handa
2018-10-02  6:38                                                                                       ` Sergey Senozhatsky
2018-10-08 10:31                                                                                         ` Tetsuo Handa
2018-10-08 16:03                                                                                           ` Petr Mladek
2018-10-08 20:48                                                                                             ` Tetsuo Handa
2018-10-09 14:52                                                                                               ` Petr Mladek
2018-10-09 21:19                                                                                                 ` Tetsuo Handa
2018-10-10 10:14                                                                                                   ` Tetsuo Handa
2018-10-11 10:20                                                                                                     ` Tetsuo Handa
2018-10-11 13:47                                                                                                       ` Steven Rostedt
2018-10-08 15:43                                                                                         ` Petr Mladek
2018-09-28  8:56                                                                         ` Sergey Senozhatsky
2018-09-28 11:21                                                                           ` Tetsuo Handa
2018-09-29 11:13                                                                             ` Sergey Senozhatsky
2018-09-29 11:39                                                                               ` Tetsuo Handa
2018-10-01  5:52                                                                               ` Sergey Senozhatsky
2018-10-01  8:37                                                                                 ` Sergey Senozhatsky
2018-10-01 18:06                                                                               ` Steven Rostedt
2018-09-14  1:12                                                         ` Steven Rostedt
2018-09-14  1:55                                                           ` Sergey Senozhatsky
2018-06-21  8:29                                               ` Sergey Senozhatsky
2018-06-20  9:30                                       ` Dmitry Vyukov
2018-06-20 11:19                                         ` Sergey Senozhatsky
2018-06-20 11:25                                           ` Dmitry Vyukov
2018-06-20 11:37                                         ` Fengguang Wu
2018-06-20 12:31                                           ` Dmitry Vyukov
2018-06-20 12:41                                             ` Fengguang Wu
2018-06-20 12:45                                               ` Dmitry Vyukov
2018-06-20 12:48                                                 ` Fengguang Wu
2018-05-11 13:37                     ` printk feature for syzbot? Steven Rostedt
2018-05-15  5:20                       ` Sergey Senozhatsky
2018-05-15 14:39                         ` Steven Rostedt
2018-05-11 11:02                 ` [PATCH] printk: fix possible reuse of va_list variable Tetsuo Handa
2018-05-11 11:27                   ` Sergey Senozhatsky
2018-05-17 11:57                   ` Petr Mladek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=49d22738-17ad-410a-be0a-d27d76ba9f37@i-love.sakura.ne.jp \
    --to=penguin-kernel@i-love.sakura.ne.jp \
    --cc=akpm@linux-foundation.org \
    --cc=dvyukov@google.com \
    --cc=fengguang.wu@intel.com \
    --cc=glider@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pmladek@suse.com \
    --cc=rostedt@goodmis.org \
    --cc=sergey.senozhatsky.work@gmail.com \
    --cc=sergey.senozhatsky@gmail.com \
    --cc=syzkaller@googlegroups.com \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git
	git clone --mirror https://lore.kernel.org/lkml/10 lkml/git/10.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git