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From: Pavel Machek <pavel@ucw.cz>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>,
	Christoph Hellwig <hch@infradead.org>,
	hpa@zytor.com, tglx@linutronix.de, andi@firstfloor.org,
	linux-kernel@vger.kernel.org,
	Arjan van de Ven <arjan@linux.intel.com>
Subject: Re: [patch 2/2] x86, fpu: lazy allocation of FPU area - v3
Date: Wed, 5 Mar 2008 20:47:06 +0100	[thread overview]
Message-ID: <20080305194705.GA4386@ucw.cz> (raw)
In-Reply-To: <20080304175528.GD28006@linux-os.sc.intel.com>

On Tue 2008-03-04 09:55:28, Suresh Siddha wrote:
> On Tue, Mar 04, 2008 at 11:32:20AM +0100, Ingo Molnar wrote:
> > 
> > * Suresh Siddha <suresh.b.siddha@intel.com> wrote:
> > 
> > > On Mon, Mar 03, 2008 at 08:20:12PM -0500, Christoph Hellwig wrote:
> > > > On Mon, Mar 03, 2008 at 03:02:46PM -0800, Suresh Siddha wrote:
> > > > > +	/*
> > > > > +	 * Memory allocation at the first usage of the FPU and other state.
> > > > > +	 */
> > > > > +	if (!tsk->thread.xstate)
> > > > > +		tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
> > > >
> > > >  Also don't we need some kind of error handling here?
> > > 
> > > Currently it uses SLAB_PANIC.
> > 
> > but SLAB_PANIC only covers kmem_cache_create() failures. 
> > 
> > kmem_cache_alloc() can fail (return NULL) and not handling it is a bug.
> 
> oops. you are correct. Will send a sigsegv in the failure case then. Thanks.

You are introducing possibility of hard to debug error, where previous
code just worked... Does not look like good idea to me.
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2008-03-06 14:46 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-03 23:02 [patch 1/2] x86, fpu: split FPU state from task struct " Suresh Siddha
2008-03-03 23:02 ` [patch 2/2] x86, fpu: lazy allocation of FPU area " Suresh Siddha
2008-03-04  1:20   ` Christoph Hellwig
2008-03-04  1:43     ` Suresh Siddha
2008-03-04 10:32       ` Ingo Molnar
2008-03-04 17:55         ` Suresh Siddha
2008-03-05 19:47           ` Pavel Machek [this message]
2008-03-06 15:51             ` Ingo Molnar
2008-03-06 19:10               ` Suresh Siddha
2008-03-06 20:24               ` Pavel Machek
2008-03-06 20:52                 ` Andi Kleen
2008-03-07 12:29                 ` H. Peter Anvin
2008-03-07 13:06                   ` Arjan van de Ven
2008-03-07 13:18                     ` Andi Kleen
2008-03-07 13:20                       ` Arjan van de Ven
2008-03-07 13:27                         ` Andi Kleen
2008-03-05 19:48   ` Pavel Machek
2008-03-06 19:26     ` Suresh Siddha
2008-03-06 21:21       ` Pavel Machek
2008-03-04  1:18 ` [patch 1/2] x86, fpu: split FPU state from task struct " Christoph Hellwig
2008-03-04  1:36   ` Suresh Siddha
2008-03-04  8:20     ` Ingo Molnar
2008-03-06 12:39     ` Christoph Hellwig
2008-03-04 10:28 ` Ingo Molnar
2008-03-04 17:59   ` Suresh Siddha
2008-03-04 20:53     ` Ingo Molnar

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