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From: Thomas Huth <thuth@redhat.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
	linuxppc-dev@lists.ozlabs.org, nfont@linux.vnet.ibm.com
Cc: paulus@samba.org, anton@samba.org, kvm-ppc@vger.kernel.org
Subject: Re: powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers
Date: Wed, 22 Jul 2015 11:40:01 +0000	[thread overview]
Message-ID: <55AF8111.4080905@redhat.com> (raw)
In-Reply-To: <20150722112527.B36E01402C8@ozlabs.org>

On 22/07/15 13:25, Michael Ellerman wrote:
> On Fri, 2015-17-07 at 10:46:58 UTC, Thomas Huth wrote:
>> The EPOW interrupt handler uses rtas_get_sensor(), which in turn
>> uses rtas_busy_delay() to wait for RTAS becoming ready in case it
>> is necessary. But rtas_busy_delay() is annotated with might_sleep()
>> and thus may not be used by interrupts handlers like the EPOW handler!
>> This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is
>> enabled:
> 
> When did we break this?

 Hi Michael,

the bug has been introduced by commit 587f83e8dd50d22bc0c62e32ec49fd31
("powerpc/pseries: Use rtas_get_sensor in RAS code") which switched the
EPOW handler to use rtas_get_sensor() instead of using rtas_call directly.

Also have a look at this thread here:
http://www.spinics.net/lists/kvm-ppc/msg10768.html

 Thomas



WARNING: multiple messages have this Message-ID (diff)
From: Thomas Huth <thuth@redhat.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
	linuxppc-dev@lists.ozlabs.org, nfont@linux.vnet.ibm.com
Cc: paulus@samba.org, anton@samba.org, kvm-ppc@vger.kernel.org
Subject: Re: powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers
Date: Wed, 22 Jul 2015 13:40:01 +0200	[thread overview]
Message-ID: <55AF8111.4080905@redhat.com> (raw)
In-Reply-To: <20150722112527.B36E01402C8@ozlabs.org>

On 22/07/15 13:25, Michael Ellerman wrote:
> On Fri, 2015-17-07 at 10:46:58 UTC, Thomas Huth wrote:
>> The EPOW interrupt handler uses rtas_get_sensor(), which in turn
>> uses rtas_busy_delay() to wait for RTAS becoming ready in case it
>> is necessary. But rtas_busy_delay() is annotated with might_sleep()
>> and thus may not be used by interrupts handlers like the EPOW handler!
>> This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is
>> enabled:
> 
> When did we break this?

 Hi Michael,

the bug has been introduced by commit 587f83e8dd50d22bc0c62e32ec49fd31
("powerpc/pseries: Use rtas_get_sensor in RAS code") which switched the
EPOW handler to use rtas_get_sensor() instead of using rtas_call directly.

Also have a look at this thread here:
http://www.spinics.net/lists/kvm-ppc/msg10768.html

 Thomas

  reply	other threads:[~2015-07-22 11:40 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-17 10:46 [PATCH] powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers Thomas Huth
2015-07-17 10:46 ` Thomas Huth
2015-07-20 15:11 ` Nathan Fontenot
2015-07-20 15:11   ` Nathan Fontenot
2015-07-22 11:25 ` Michael Ellerman
2015-07-22 11:25   ` Michael Ellerman
2015-07-22 11:40   ` Thomas Huth [this message]
2015-07-22 11:40     ` Thomas Huth
2015-08-03  1:35   ` Michael Ellerman
2015-08-03  1:35     ` Michael Ellerman
2015-07-29 12:13 ` [PATCH] " Thomas Huth
2015-07-29 12:13   ` Thomas Huth

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