[PATCH 2.6.23-rc3-mm1] request_irq fix DEBUG_SHIRQ handling Re: 2.6.23-rc2-mm1: rtl8139 inconsistent lock state

Jarek Poplawski
2007-08-22T13:34:21Z

On 10-08-2007 01:49, Mariusz Kozlowski wrote:
> Hello,
>
> =================================
> [ INFO: inconsistent lock state ]
> 2.6.23-rc2-mm1 #7
> ---------------------------------
> inconsistent {in-hardirq-W} -> {hardirq-on-W} usage.
> ifconfig/5492 [HC0[0]:SC0[0]:HE1:SE1] takes:
> (&tp->lock){+...}, at: [<de8706e0>] rtl8139_interrupt+0x27/0x46b [8139too]
> {in-hardirq-W} state was registered at:
> [<c0138eeb>] __lock_acquire+0x949/0x11ac
> [<c01397e7>] lock_acquire+0x99/0xb2
> [<c0452ff3>] _spin_lock+0x35/0x42
> [<de8706e0>] rtl8139_interrupt+0x27/0x46b [8139too]
> [<c0147a5d>] handle_IRQ_event+0x28/0x59
> [<c01493ca>] handle_level_irq+0xad/0x10b
> [<c0105a13>] do_IRQ+0x93/0xd0
> [<c010441e>] common_interrupt+0x2e/0x34
...
> other info that might help us debug this:
> 1 lock held by ifconfig/5492:
> #0: (rtnl_mutex){--..}, at: [<c0451778>] mutex_lock+0x1c/0x1f
>
> stack backtrace:
...
> [<c0452ff3>] _spin_lock+0x35/0x42
> [<de8706e0>] rtl8139_interrupt+0x27/0x46b [8139too]
> [<c01480fd>] free_irq+0x11b/0x146
> [<de871d59>] rtl8139_close+0x8a/0x14a [8139too]
> [<c03bde63>] dev_close+0x57/0x74
...

It looks like this was possible after David's fix, which really
enabled running of the handler in free_irq, but before Andrew's patch
disabling local irqs for this time.

So, this bug should be fixed, but IMHO similar problem is possible in
request_irq. And, I think, this is not only about lockdep complaining,
but real lockup possibility, because any locks in such a handler are
taken in another, not expected for them context, and could be
vulnerable (especially with softirqs, but probably hardirqs as well).

Reported-by: Mariusz Kozlowski <m.kozlowski@tuxland.pl>
Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>

---

diff -Nurp 2.6.23-rc3-mm1-/kernel/irq/manage.c 2.6.23-rc3-mm1/kernel/irq/manage.c
--- 2.6.23-rc3-mm1-/kernel/irq/manage.c 2007-08-22 13:58:58.000000000 +0200
+++ 2.6.23-rc3-mm1/kernel/irq/manage.c 2007-08-22 14:12:21.000000000 +0200
@@ -546,14 +546,11 @@ int request_irq(unsigned int irq, irq_ha
* We do this before actually registering it, to make sure that
* a 'real' IRQ doesn't run in parallel with our fake
*/
- if (irqflags & IRQF_DISABLED) {
- unsigned long flags;
+ unsigned long flags;

- local_irq_save(flags);
- handler(irq, dev_id);
- local_irq_restore(flags);
- } else
- handler(irq, dev_id);
+ local_irq_save(flags);
+ handler(irq, dev_id);
+ local_irq_restore(flags);
}
#endif