From: Andrew Morton <akpm@linux-foundation.org>
To: corbet@lwn.net (Jonathan Corbet)
Cc: stern@rowland.harvard.edu, khali@linux-fr.org, mb@bu3sch.de,
hmh@hmh.eng.br, david-b@pacbell.net, rpurdie@rpsys.net,
linux-kernel@vger.kernel.org, mingo@elte.hu,
geert@linux-m68k.org
Subject: Re: use of preempt_count instead of in_atomic() at leds-gpio.c
Date: Mon, 24 Mar 2008 12:42:29 -0700 [thread overview]
Message-ID: <20080324124229.5d49ded6.akpm@linux-foundation.org> (raw)
In-Reply-To: <23456.1206387289@vena.lwn.net>
On Mon, 24 Mar 2008 13:34:49 -0600
corbet@lwn.net (Jonathan Corbet) wrote:
> Discourage people from using in_atomic()
>
> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
>
> diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
> index 4982998..3d196cb 100644
> --- a/include/linux/hardirq.h
> +++ b/include/linux/hardirq.h
> @@ -72,6 +72,11 @@
> #define in_softirq() (softirq_count())
> #define in_interrupt() (irq_count())
>
> +/*
> + * Are we running in atomic context? WARNING: this macro cannot
> + * always detect atomic context and should not be used to determine
> + * whether sleeping is possible. Do not use it in driver code.
> + */
> #define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != 0)
It'd be better if the comment were to describe _why_ in_atomic() is
unreliable. ie: "does not account for held spinlocks on non-preemptible
kernels".
next prev parent reply other threads:[~2008-03-24 19:43 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-16 18:43 use of preempt_count instead of in_atomic() at leds-gpio.c Henrique de Moraes Holschuh
2008-03-16 19:46 ` David Brownell
2008-03-18 7:14 ` Andrew Morton
2008-03-18 19:06 ` David Brownell
2008-03-18 20:07 ` Andrew Morton
2008-03-20 22:56 ` Henrique de Moraes Holschuh
2008-03-20 23:47 ` Andrew Morton
2008-03-21 0:36 ` Henrique de Moraes Holschuh
2008-03-21 1:08 ` Andrew Morton
2008-03-21 1:31 ` Alan Stern
2008-03-21 1:31 ` Alan Stern
2008-03-21 1:36 ` Michael Buesch
2008-03-21 1:36 ` Michael Buesch
2008-03-21 2:27 ` Andrew Morton
2008-03-21 2:27 ` Andrew Morton
2008-03-21 3:07 ` Alan Stern
2008-03-21 3:07 ` Alan Stern
2008-03-21 3:17 ` Andrew Morton
2008-03-21 3:17 ` Andrew Morton
2008-03-21 9:53 ` Jean Delvare
2008-03-21 17:37 ` Andrew Morton
2008-03-21 18:05 ` Alan Stern
2008-03-24 19:34 ` Jonathan Corbet
2008-03-24 19:42 ` Andrew Morton [this message]
2008-03-24 19:53 ` Jonathan Corbet
2008-03-25 8:52 ` Junio C Hamano
2008-03-25 10:39 ` Jean Delvare
2008-03-25 13:44 ` Jonathan Corbet
2008-03-25 23:20 ` David Brownell
2008-03-26 14:28 ` Alan Stern
2008-03-26 16:17 ` Henrique de Moraes Holschuh
2008-03-26 16:46 ` Richard Purdie
2008-03-27 18:51 ` David Brownell
2008-03-21 15:11 ` Tetsuo Handa
2008-03-21 16:54 ` Stefan Richter
2008-03-21 17:02 ` Stefan Richter
2008-03-23 5:53 ` Tetsuo Handa
2008-03-21 13:47 ` Heiko Carstens
2008-03-21 13:47 ` Heiko Carstens
2008-03-21 16:54 ` Greg KH
2008-03-21 16:54 ` Greg KH
2008-03-21 19:59 ` Andrew Morton
2008-03-21 19:59 ` Andrew Morton
2008-03-21 20:16 ` Michael Buesch
2008-03-21 20:16 ` Michael Buesch
2008-03-21 20:20 ` Michael Buesch
2008-03-21 20:20 ` Michael Buesch
2008-03-21 9:21 ` Stefan Richter
2008-03-21 9:21 ` Stefan Richter
2008-03-21 9:27 ` Stefan Richter
2008-03-21 9:27 ` Stefan Richter
2008-03-21 12:37 ` Henrique de Moraes Holschuh
2008-03-21 12:37 ` Henrique de Moraes Holschuh
2008-03-21 13:16 ` Stefan Richter
2008-03-22 11:29 ` Stefan Richter
2008-03-22 11:29 ` Stefan Richter
[not found] ` <20080320180802.426ad2d1.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2008-03-21 15:42 ` Use of in_atomic in i2c_transfer (Was: use of preempt_count instead of in_atomic() at leds-gpio.c) Jean Delvare
[not found] ` <20080321164235.26c95e17-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2008-03-21 16:00 ` Russell King - ARM Linux
2008-03-21 17:04 ` use of preempt_count instead of in_atomic() at leds-gpio.c David Brownell
2008-03-21 17:04 ` David Brownell
2008-03-21 17:04 ` David Brownell
2008-03-21 0:56 ` Richard Purdie
2008-03-21 2:10 ` Henrique de Moraes Holschuh
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