2006-11-21 08:53:06

by Pavel Emelyanov

[permalink] [raw]

Subject: [RFC][PATCH] Fix locking on misrouted interrupts

---

--- ./kernel/irq/chip.c.noteintfix 2006-11-21 11:27:18.000000000 +0300
+++ ./kernel/irq/chip.c 2006-11-21 11:48:18.000000000 +0300
@@ -281,10 +281,11 @@ handle_simple_irq(unsigned int irq, stru
spin_unlock(&desc->lock);

action_ret = handle_IRQ_event(irq, action);
+
+ spin_lock(&desc->lock);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);

- spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
out_unlock:
spin_unlock(&desc->lock);
@@ -330,10 +331,11 @@ handle_level_irq(unsigned int irq, struc
spin_unlock(&desc->lock);

action_ret = handle_IRQ_event(irq, action);
+
+ spin_lock(&desc->lock);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);

- spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
desc->chip->unmask(irq);
@@ -381,10 +383,11 @@ handle_fasteoi_irq(unsigned int irq, str
spin_unlock(&desc->lock);

action_ret = handle_IRQ_event(irq, action);
+
+ spin_lock(&desc->lock);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);

- spin_lock(&desc->lock);
desc->status &= ~IRQ_INPROGRESS;
out:
desc->chip->eoi(irq);
@@ -460,10 +463,12 @@ handle_edge_irq(unsigned int irq, struct

desc->status &= ~IRQ_PENDING;
spin_unlock(&desc->lock);
+
action_ret = handle_IRQ_event(irq, action);
+
+ spin_lock(&desc->lock);
if (!noirqdebug)
note_interrupt(irq, desc, action_ret);
- spin_lock(&desc->lock);

} while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);

@@ -483,6 +488,7 @@ out_unlock:
void fastcall
handle_percpu_irq(unsigned int irq, struct irq_desc *desc)
{
+ unsigned long flags;
irqreturn_t action_ret;

kstat_this_cpu.irqs[irq]++;
@@ -491,8 +497,11 @@ handle_percpu_irq(unsigned int irq, stru
desc->chip->ack(irq);

action_ret = handle_IRQ_event(irq, desc->action);
- if (!noirqdebug)
+ if (!noirqdebug) {
+ spin_lock_irqsave(&desc->lock, flags);
note_interrupt(irq, desc, action_ret);
+ spin_unlock_irqrestore(&desc->lock, flags);
+ }

if (desc->chip->eoi)
desc->chip->eoi(irq);

---

Attachments:

diff-note-interrupt-locking-fix (2.04 kB)

2006-11-21 20:28:46

by Ingo Molnar

[permalink] [raw]

Subject: Re: [RFC][PATCH] Fix locking on misrouted interrupts

---

On Tue, 2006-11-21 at 11:48 +0300, Pavel Emelianov wrote:
> Vivek noted that many places call note_interrupt()
> without desc->lock being held. Since note_interrupt()
> which tries to unlock this lock to handle spurious
> interrupts accodring to
> http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f72fa707604c015a6625e80f269506032d5430dc
>
> Looking at note_interrupt() I found that desc->lock
> IS required in this function but all the places that
> call note_interrupt() lock it after the call. One
> exception from this rule is __do_IRQ().
>
> So I move spin_lock(&desc->lock); before calling
> note_interrupt() in all places.
>
> Signed-off-bt: Pavel Emelianov <[email protected]>

indeed - and this is a fallout of the earlier fix in note_interrupt().
Andrew, Linus: i think this is a must-have for 2.6.19 as well.

Acked-by: Ingo Molnar <[email protected]>

Ingo