LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Steven Rostedt <rostedt@goodmis.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 00/16 v3] tracing: Add new file system tracefs
Date: Mon, 26 Jan 2015 19:39:09 -0500	[thread overview]
Message-ID: <20150126193909.19967bd0@grimm.local.home> (raw)
In-Reply-To: <20150126184916.70d88963@gandalf.local.home>

On Mon, 26 Jan 2015 18:49:16 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 26 Jan 2015 18:43:14 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
>  
> > That is, we can not hold i_mutex and take trace_types_lock.
> > 
> > trace_types_lock needs to be held with the creation or destruction
> > of events, which is what mkdir an rmdir do.
> 
> Although, I can not remember how this happened, but lockdep blew up on
> me with this. I'll look again.

OK, found it. When events are created (module is loaded), the
trace_types_lock is taken, and the event directories are created (these
are in /sys/kernel/debug/tracing/events). We need to grab the i_mutex
in order to create these files.

This means that we can not take the trace_types_lock within the mkdir
or rmdir calls.

The directories are not static even outside the mkdir and rmdir calls.
As events can be created from several sources, which will create new
files and directories.

-- Steve

  reply	other threads:[~2015-01-27  0:38 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-26 15:09 Steven Rostedt
2015-01-26 15:09 ` [PATCH 01/16 v3] debugfs_{mkdir,create,link}(): get rid of redundant argument Steven Rostedt
2015-01-26 15:09 ` [PATCH 02/16 v3] debugfs: split the beginning and the end of __create_file() off Steven Rostedt
2015-01-26 15:09 ` [PATCH 03/16 v3] debugfs: kill __create_file() Steven Rostedt
2015-01-26 15:09 ` [PATCH 04/16 v3] fold debugfs_link() into caller Steven Rostedt
2015-01-26 15:09 ` [PATCH 05/16 v3] debugfs_mknod(): get rid useless arguments Steven Rostedt
2015-01-26 15:09 ` [PATCH 06/16 v3] fold debugfs_mkdir() into caller Steven Rostedt
2015-01-26 15:09 ` [PATCH 07/16 v3] fold debugfs_create() " Steven Rostedt
2015-01-26 15:09 ` [PATCH 08/16 v3] fold debugfs_mknod() into callers Steven Rostedt
2015-01-26 15:09 ` [PATCH 09/16 v3] debugfs: take mode-dependent parts of debugfs_get_inode() " Steven Rostedt
2015-01-26 15:09 ` [PATCH 10/16 v3] debugfs: split end_creating() into success and failure cases Steven Rostedt
2015-01-26 15:09 ` [PATCH 11/16 v3] new primitive: debugfs_create_automount() Steven Rostedt
2015-01-26 15:09 ` [PATCH 12/16 v3] tracefs: Add new tracefs file system Steven Rostedt
2015-01-26 15:09 ` [PATCH 13/16 v3] tracing: Convert the tracing facility over to use tracefs Steven Rostedt
2015-01-26 15:09 ` [PATCH 14/16 v3] tracing: Automatically mount tracefs on debugfs/tracing Steven Rostedt
2015-01-26 15:09 ` [PATCH 15/16 v3] tracefs: Add directory /sys/kernel/tracing Steven Rostedt
2015-01-26 15:09 ` [PATCH 16/16 v3] tracing: Have mkdir and rmdir be part of tracefs Steven Rostedt
2015-01-26 19:30 ` [PATCH 00/16 v3] tracing: Add new file system tracefs Al Viro
2015-01-26 20:42   ` Steven Rostedt
2015-01-26 20:44     ` Steven Rostedt
2015-01-26 20:58       ` Steven Rostedt
2015-01-26 21:44         ` Al Viro
2015-01-26 21:46     ` Al Viro
2015-01-26 23:02       ` Al Viro
2015-01-26 23:39         ` Steven Rostedt
2015-01-26 23:43       ` Steven Rostedt
2015-01-26 23:49         ` Steven Rostedt
2015-01-27  0:39           ` Steven Rostedt [this message]
2015-01-27  4:34             ` Al Viro
2015-01-27 15:15               ` Steven Rostedt
2015-01-27  0:37         ` Al Viro
2015-01-27  1:02           ` Steven Rostedt
2015-01-27  1:03             ` Steven Rostedt
2015-01-27  4:38               ` Al Viro
2015-01-27 15:19                 ` Steven Rostedt
2015-01-27 15:44                   ` Steven Rostedt
2015-01-26 21:40   ` Al Viro
2015-01-26 23:37     ` Steven Rostedt
2015-01-27  2:34       ` Steven Rostedt
2015-01-27  4:46         ` Al Viro

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=20150126193909.19967bd0@grimm.local.home \
    --to=rostedt@goodmis.org \
    --cc=akpm@linux-foundation.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=viro@ZenIV.linux.org.uk \
    --subject='Re: [PATCH 00/16 v3] tracing: Add new file system tracefs' \
    /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

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).