From: Greg KH <gregkh@suse•de>
To: linux-kernel@vger•kernel.org, stable@kernel•org
Cc: stable-review@kernel•org, linuxppc-dev <linuxppc-dev@ozlabs•org>,
Thomas Gleixner <tglx@linutronix•de>,
torvalds@linux-foundation•org, akpm@linux-foundation•org,
alan@lxorguk•ukuu.org.uk
Subject: [050/165] genirq: Deal with desc->set_type() changing desc->chip
Date: Fri, 30 Jul 2010 10:14:38 -0700 [thread overview]
Message-ID: <20100730171504.200218674@clark.site> (raw)
In-Reply-To: <20100730171550.GA1299@kroah.com
2.6.32-stable review patch. If anyone has any objections, please let us know.
------------------
From: Thomas Gleixner <tglx@linutronix•de>
commit 4673247562e39a17e09440fa1400819522ccd446 upstream.
The set_type() function can change the chip implementation when the
trigger mode changes. That might result in using an non-initialized
irq chip when called from __setup_irq() or when called via
set_irq_type() on an already enabled irq.
The set_irq_type() function should not be called on an enabled irq,
but because we forgot to put a check into it, we have a bunch of users
which grew the habit of doing that and it never blew up as the
function is serialized via desc->lock against all users of desc->chip
and they never hit the non-initialized irq chip issue.
The easy fix for the __setup_irq() issue would be to move the
irq_chip_set_defaults(desc->chip) call after the trigger setting to
make sure that a chip change is covered.
But as we have already users, which do the type setting after
request_irq(), the safe fix for now is to call irq_chip_set_defaults()
from __irq_set_trigger() when desc->set_type() changed the irq chip.
It needs a deeper analysis whether we should refuse to change the chip
on an already enabled irq, but that'd be a large scale change to fix
all the existing users. So that's neither stable nor 2.6.35 material.
Reported-by: Esben Haabendal <eha@doredevelopment•dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix•de>
Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linuxppc-dev <linuxppc-dev@ozlabs•org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse•de>
---
kernel/irq/manage.c | 3 +++
1 file changed, 3 insertions(+)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -436,6 +436,9 @@ int __irq_set_trigger(struct irq_desc *d
/* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
desc->status |= flags;
+
+ if (chip != desc->chip)
+ irq_chip_set_defaults(desc->chip);
}
return ret;
reply other threads:[~2010-07-30 17:18 UTC|newest]
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