linux-kernel - Re: [PATCH 02/10] perf, trace: Use per-tracepoint-per-cpu hlist to track events

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1274437149.1674.1697.camel@laptop>
Date:	Fri, 21 May 2010 12:19:09 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/10] perf, trace: Use per-tracepoint-per-cpu hlist to
 track events

On Fri, 2010-05-21 at 12:13 +0200, Frederic Weisbecker wrote:
> > I assumed that after probe unregister a tracepoint callback doesn't
> > happen, which then guarantees we should never get !head.

> I'm not sure about this. The tracepoints are called under rcu_read_lock(),
> but there is not synchronize_rcu() after we unregister a tracepoint, which
> means you can have a pending preempted one somewhere.
> 
> There is a call_rcu that removes the callbacks, but that only protect
> the callback themselves. 

Ah, ok, so we should do probe_unregister + synchronize_sched().

That should ensure __DO_TRACE() doesn't call into it anymore.

/me goes make a patch

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/