linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Subject: [PATCH] printk: don't unconditionally shortcut print_time()
Date: Sat, 24 Nov 2018 19:50:13 +0900	[thread overview]
Message-ID: <1543056613-4779-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> (raw)

Since /sys/module/printk/parameters/time can change from N to Y between
"msg_print_text() called print_prefix() with buf == NULL" and
"msg_print_text() again calls print_prefix() with buf != NULL", it is not
safe for print_time() to unconditionally return 0 if printk_time == false.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 kernel/printk/printk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5c2079d..df7ced0 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1230,7 +1230,7 @@ static size_t print_time(u64 ts, char *buf)
 {
 	unsigned long rem_nsec;
 
-	if (!printk_time)
+	if (!printk_time && buf)
 		return 0;
 
 	rem_nsec = do_div(ts, 1000000000);
-- 
1.8.3.1


             reply	other threads:[~2018-11-24 10:51 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-24 10:50 Tetsuo Handa [this message]
2018-11-24 14:28 ` [PATCH] printk: deduplicate print_prefix() calls Tetsuo Handa
2018-11-26  7:56   ` Sergey Senozhatsky
2018-11-26 10:21     ` Tetsuo Handa
2018-11-29 14:35   ` Petr Mladek
2018-11-29 14:19 ` [PATCH] printk: don't unconditionally shortcut print_time() Petr Mladek
2018-11-30  2:26   ` Tetsuo Handa
2018-11-30 12:30     ` Petr Mladek
2018-11-30 14:33       ` Tetsuo Handa
2018-12-01 11:30         ` Tetsuo Handa
2018-12-02  5:02           ` Tetsuo Handa
2018-12-03 13:16             ` Petr Mladek
2018-12-04  2:56             ` Sergey Senozhatsky
2018-12-04 10:06               ` Tetsuo Handa
2018-12-04 10:59                 ` Sergey Senozhatsky
2018-12-03 14:14         ` Petr Mladek
2018-12-03 15:00           ` Tetsuo Handa
2018-11-30  4:24   ` Sergey Senozhatsky

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=1543056613-4779-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp \
    --to=penguin-kernel@i-love.sakura.ne.jp \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pmladek@suse.com \
    --cc=rostedt@goodmis.org \
    --cc=sergey.senozhatsky@gmail.com \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).