linux-kernel - Re: [PATCH] export get_task

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Message-Id: <20090127010035.18521a3b.akpm@linux-foundation.org>
Date:	Tue, 27 Jan 2009 01:00:35 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	Kyle McMartin <kyle@...radead.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Christoph Bartelmus <lirc@...telmus.de>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Whitcroft <apw@...dowen.org>
Subject: Re: [PATCH] export get_task_comm()

On Tue, 27 Jan 2009 11:49:56 +0300 Alexey Dobriyan <adobriyan@...il.com> wrote:

> On Mon, Jan 26, 2009 at 09:29:18PM -0800, Andrew Morton wrote:
> > On Mon, 26 Jan 2009 21:26:15 -0800 Andrew Morton <akpm@...ux-foundation.org> wrote:
> > 
> > > On Tue, 27 Jan 2009 00:19:19 -0500 Kyle McMartin <kyle@...radead.org> wrote:
> > > 
> > > > On Mon, Jan 26, 2009 at 09:16:55PM -0800, Andrew Morton wrote:
> > > > > Ho hum, I suppose so.  I redid the changelog a bit:
> > > > > 
> > > > >    task_struct.comm[] is useful for debugging and driver developers
> > > > >    want to use this information easily.  Direct access to
> > > > >    task_struct.comm[] is a bit racy, so export the official accessor.
> > > > > 
> > > > 
> > > > Maybe lirc should be submitted to staging/ before we go exporting
> > > > symbols for out of tree things... ;-)
> > > 
> > > y:/usr/src/linux-2.6.29-rc2> grep -r 'current->comm' drivers | wc -l
> > > 77
> > > 
> > > :(
> > 
> > It's worth a checkpatch rule, I guess: "direct access to
> > task_struct.comm is racy - use get_task_comm()".
> 
> And majority of usages is some debugging printk where nobody cares if ->comm
> corrupted.
> 
> Changelog says is useful for debugging. That's right, tsk->comm is useful
> for debugging, not allocating temporary buffer + get_task_comm().
> 
> Some ->comm usages are for kernel threads which never change it, for starters.
> 
> current->comm is always safe, because, current is not executing prctl(2)! 

That's a good point.

> I'd say nothing should be done and, heavens forbid, adding this to checkpatch.pl.

hm, yeah, OK, I'll drop it.
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