From: Frederic Weisbecker <fweisbec@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 1/5] tracing: Prevent kernel oops with corrupted buffer
Date: Tue, 26 Jan 2010 23:39:02 +0100 [thread overview]
Message-ID: <20100126223900.GA5223@nowhere> (raw)
In-Reply-To: <20100126143223.e4332098.akpm@linux-foundation.org>
On Tue, Jan 26, 2010 at 02:32:23PM -0800, Andrew Morton wrote:
> > + if (WARN_ON_ONCE(pid < 0)) {
> > + strcpy(comm, "<XXX>");
> > + return;
> > + }
> > +
> > if (pid > PID_MAX_DEFAULT) {
> > strcpy(comm, "<...>");
> > return;
>
> But why is it WARN_ON_ONCE()? That will only fix the problem a single
> time. On the second occurrence, it will oops again.
The warning will be produced only once, but after that,
the condition is still checked like a simple if:
#define WARN_ON_ONCE(condition) ({ \
static bool __warned; \
int __ret_warn_once = !!(condition); \
\
if (unlikely(__ret_warn_once)) \
if (WARN_ON(!__warned)) \
__warned = true; \
unlikely(__ret_warn_once); \
})
And since this function can be called anytime we have a trace
to print to the user, we don't want to encumber with thousands
of warnings.
next prev parent reply other threads:[~2010-01-26 22:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-26 22:09 [PATCH 0/5][GIT PULL][v2.6.33] tracing: fixes and documentation updates Steven Rostedt
2010-01-26 22:09 ` [PATCH 1/5] tracing: Prevent kernel oops with corrupted buffer Steven Rostedt
2010-01-26 22:32 ` Andrew Morton
2010-01-26 22:39 ` Frederic Weisbecker [this message]
2010-01-26 23:20 ` Steven Rostedt
2010-01-26 23:24 ` Steven Rostedt
2010-01-26 22:09 ` [PATCH 2/5] ring-buffer: Check if ring buffer iterator has stale data Steven Rostedt
2010-01-26 22:09 ` [PATCH 3/5] ring-buffer: Check for end of page in iterator Steven Rostedt
2010-01-26 22:09 ` [PATCH 4/5] tracing/documentation: Fix a typo in ftrace.txt Steven Rostedt
2010-01-26 22:09 ` [PATCH 5/5] tracing/documentation: Cover new frame pointer semantics Steven Rostedt
2010-01-27 9:37 ` [PATCH 0/5][GIT PULL][v2.6.33] tracing: fixes and documentation updates Ingo Molnar
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=20100126223900.GA5223@nowhere \
--to=fweisbec@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=rostedt@goodmis.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
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