From: Steven Rostedt <rostedt@goodmis.org>
To: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kees Cook <keescook@chromium.org>,
Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
John Stultz <john.stultz@linaro.org>,
Shuah Khan <shuahkhan@gmail.com>,
arve@android.com, Rebecca Schultz Zavin <rebecca@android.com>,
Jesper Juhl <jj@chaosbits.net>,
Randy Dunlap <rdunlap@xenotime.net>,
Thomas Meyer <thomas@m3y3r.de>,
Andrew Morton <akpm@linux-foundation.org>,
Marco Stornelli <marco.stornelli@gmail.com>,
WANG Cong <xiyou.wangcong@gmail.com>,
linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org,
linaro-kernel@lists.linaro.org, patches@linaro.org,
kernel-team@android.com, Stephen Boyd <sboyd@codeaurora.org>
Subject: Re: [PATCH v3] pstore/ftrace: Convert to its own enable/disable debugfs knob
Date: Tue, 21 Aug 2012 22:25:00 -0400 [thread overview]
Message-ID: <1345602300.5069.25.camel@gandalf.local.home> (raw)
In-Reply-To: <20120822021017.GA13779@lizard>
On Tue, 2012-08-21 at 19:10 -0700, Anton Vorontsov wrote:
> Running without any recursion protection is prone to weird
> lockups/reboots, and probably a good idea to have it on a production
> system. But recursion during tracing is still an evidence of some other
> bugs, right? At least the fact that I didn't have it helped me to find a
> bug. So, does it make sense to make the recursion protection optionally
> disabled? Maybe as some CONFIG_DEBUG_* option (briefly looking into
> kernel/trace/Kconfig I didn't find any)?
The problem is that recursion bugs are usually due to calling something
that might be traced. Really, I've hit so many recursion bugs, that
having the protection is probably the best thing. I wouldn't turn it
off.
The worse that recursion can do (with proper protection) is that it
causes a little wasted effort during the trace (it wastes cycles tracing
something again and then recognizing that it is doing it due to
recursion).
Therefore, the 'notrace' annotations are mostly for speed up (don't
trace this while tracing, because the tracer uses it too).
-- Steve
next prev parent reply other threads:[~2012-08-22 2:25 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-10 0:10 [PATCH v4 0/8] Function tracing support for pstore Anton Vorontsov
2012-07-10 0:10 ` [PATCH 1/8] tracing: Fix initialization failure path in tracing_set_tracer() Anton Vorontsov
2012-07-10 0:10 ` [PATCH 2/8] pstore: Introduce write_buf backend callback Anton Vorontsov
2012-07-10 0:10 ` [PATCH 3/8] pstore: Add persistent function tracing Anton Vorontsov
2012-07-17 19:38 ` Steven Rostedt
2012-07-17 20:01 ` Anton Vorontsov
2012-07-17 21:38 ` Steven Rostedt
2012-07-17 22:06 ` Anton Vorontsov
2012-07-18 3:47 ` [PATCH] pstore/ftrace: Convert to its own enable/disable debugfs knob Anton Vorontsov
2012-07-18 7:26 ` Anton Vorontsov
2012-07-18 13:13 ` Steven Rostedt
2012-07-18 13:10 ` Steven Rostedt
2012-07-18 18:24 ` [PATCH v2] " Anton Vorontsov
2012-07-18 17:12 ` [PATCH] " Stephen Boyd
2012-07-18 18:50 ` Anton Vorontsov
2012-07-18 18:59 ` Stephen Boyd
2012-07-18 19:30 ` [PATCH v3] " Anton Vorontsov
2012-08-21 1:46 ` Anton Vorontsov
2012-08-22 1:07 ` Steven Rostedt
2012-08-22 2:10 ` Anton Vorontsov
2012-08-22 2:25 ` Steven Rostedt [this message]
2012-07-10 0:10 ` [PATCH 4/8] tracing/function: Introduce persistent trace option Anton Vorontsov
2012-07-10 12:58 ` Steven Rostedt
2012-07-10 0:10 ` [PATCH 5/8] pstore/ram: Convert to write_buf callback Anton Vorontsov
2012-07-10 0:10 ` [PATCH 6/8] pstore/ram: Add ftrace messages handling Anton Vorontsov
2012-07-10 0:10 ` [PATCH 7/8] pstore/ram: Make tracing log versioned Anton Vorontsov
2012-07-17 16:56 ` Greg Kroah-Hartman
2012-07-17 17:09 ` Anton Vorontsov
2012-07-17 18:09 ` Anton Vorontsov
2012-07-17 18:13 ` [PATCH] pstore: Headers should include all stuff they use Anton Vorontsov
2012-07-17 18:19 ` Greg Kroah-Hartman
2012-07-17 18:37 ` Anton Vorontsov
2012-07-17 19:15 ` Greg Kroah-Hartman
2012-07-17 18:18 ` [PATCH 7/8] pstore/ram: Make tracing log versioned Greg Kroah-Hartman
2012-07-17 19:11 ` [PATCH fixed] " Anton Vorontsov
2012-07-10 0:10 ` [PATCH 8/8] tracing/function: Convert func_set_flag() to a switch statement Anton Vorontsov
2012-07-10 12:01 ` [PATCH v4 0/8] Function tracing support for pstore Arnd Bergmann
2012-07-10 13:00 ` Steven Rostedt
2012-07-16 7:14 ` Anton Vorontsov
2012-07-16 14:53 ` Greg Kroah-Hartman
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