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From: catalin.marinas@arm•com (Catalin Marinas)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2 3/5] ARM: add support for kernel mode NEON
Date: Fri, 28 Jun 2013 16:46:22 +0100	[thread overview]
Message-ID: <20130628154622.GF1643@arm.com> (raw)
In-Reply-To: <CAKv+Gu92+pMLF9FPwbrkVLLhnPdBB702PXG-F2-3kqZx60TEHg@mail.gmail.com>

On Fri, Jun 28, 2013 at 03:00:02PM +0100, Ard Biesheuvel wrote:
> On 28 June 2013 15:46, Jean-Christophe PLAGNIOL-VILLARD
> <plagnioj@jcrosoft•com> wrote:
> > On 12:55 Wed 26 Jun     , Ard Biesheuvel wrote:
> >> Meh. This is not going to please the RT crowd, as preempt_schedule()
> >> will not be called on PREEMPT builds in this case.
> >>
> >> Propose to replace it with
> >>
> >>     preempt_enable();
> >> #ifndef CONFIG_PREEMPT_COUNT
> > if (IS_ENABLED(CONFIG_xxx)) at least
> >>     /* in this case, the preempt_enable() right above is just a barrier() */
> >>     dec_preempt_count();
> >> #endif
> >
> > but why do you need to call inc_preempt and dec directly?
> 
> There is a concern that violations of the rule that a task should not
> sleep between kernel_neon_begin and kernel_neon_end calls may not be
> spotted on non-PREEMPT builds that don't have
> CONFIG_DEBUG_ATOMIC_SLEEP set.

Would an explicit call to schedule() trigger with
CONFIG_DEBUG_ATOMIC_SLEEP? It looks that this config option only
triggers for explicit might_sleep() calls but we don't have one for
explicit schedule() calls (cond_resched() call has might_sleep()).

-- 
Catalin

  reply	other threads:[~2013-06-28 15:46 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-25 20:24 [PATCH v2 0/5] kernel mode NEON support Ard Biesheuvel
2013-06-25 20:24 ` [PATCH v2 1/5] ARM: move VFP init to an earlier boot stage Ard Biesheuvel
2013-06-25 20:24 ` [PATCH v2 2/5] ARM: be strict about FP exceptions in kernel mode Ard Biesheuvel
2013-06-25 20:24 ` [PATCH v2 3/5] ARM: add support for kernel mode NEON Ard Biesheuvel
2013-06-26 10:55   ` Ard Biesheuvel
2013-06-26 11:14     ` Will Deacon
2013-06-26 11:28       ` Ard Biesheuvel
2013-06-26 12:40         ` Will Deacon
2013-06-26 12:52           ` Ard Biesheuvel
2013-06-26 13:13             ` Ard Biesheuvel
2013-06-27 13:11               ` Ard Biesheuvel
2013-06-27 15:09                 ` Will Deacon
2013-06-27 15:13                 ` Catalin Marinas
2013-06-27 15:43                   ` Ard Biesheuvel
2013-06-28 10:25                   ` Ard Biesheuvel
2013-06-28 13:46     ` Jean-Christophe PLAGNIOL-VILLARD
2013-06-28 14:00       ` Ard Biesheuvel
2013-06-28 15:46         ` Catalin Marinas [this message]
2013-06-28 20:17           ` Ard Biesheuvel
2013-06-25 20:24 ` [PATCH v2 4/5] ARM: crypto: add NEON accelerated XOR implementation Ard Biesheuvel
2013-06-25 20:24 ` [PATCH v2 5/5] lib/raid6: add ARM-NEON accelerated syndrome calculation Ard Biesheuvel

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