linux-kernel - Re: [PATCH V2 -tip 3/4] Tracing/ftrace: Adapt mmiotrace to the new type of print

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Tue, 30 Sep 2008 09:33:04 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Frédéric Weisbecker <fweisbec@...il.com>
cc:	Ingo Molnar <mingo@...e.hu>, Pekka Paalanen <pq@....fi>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 -tip 3/4] Tracing/ftrace: Adapt mmiotrace to the new
 type of print_line


On Tue, 30 Sep 2008, Fr?d?ric Weisbecker wrote:

> 2008/9/30 Steven Rostedt <rostedt@...dmis.org>:
> >
> > OK, I'll nuke the ring_buffer_lock :-/
> >
> > The trace_pipe calls that and then calls print_trace_line which will
> > eventually lock the buffer again. This is a bug on my part. I'll fix that
> > today.
> >
> > Thanks,
> 
> Strange, I can't see any case where print_trace_line could call the
> ring_buffer_lock.
> Hmm, I will see in your patch.

Opps, I mean the find_next_entry_inc will do the lock.

The ring_buffer_lock locks all CPU buffers, and the find_next_entry_inc
will read from the ring buffer which will also lock the buffer. Hence
a deadlock.

-- Steve

> 
> Ingo, I just saw one damage from the merging, trace_empty() returns
> TRACE_TYPE_HANDLED. The type is wrong, it should return 1.
> It's not urgent since the value is the same. Should I send a patch for
> such a small error?
--
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/