Skip to content

Commit

Permalink
genirq: Deal with desc->set_type() changing desc->chip
Browse files Browse the repository at this point in the history
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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: linuxppc-dev <[email protected]>
Cc: [email protected]
  • Loading branch information
KAGA-KOKO committed Jun 9, 2010
1 parent 84f7586 commit 4673247
Showing 1 changed file with 3 additions and 0 deletions.
3 changes: 3 additions & 0 deletions kernel/irq/manage.c
Original file line number Diff line number Diff line change
Expand Up @@ -456,6 +456,9 @@ int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
/* 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;
Expand Down

0 comments on commit 4673247

Please sign in to comment.