From 59845b1ffd9121e5ef474ea5f27405fd7a83c85b Mon Sep 17 00:00:00 2001 From: Jarek Poplawski Date: Thu, 30 Aug 2007 23:56:34 -0700 Subject: [PATCH] request_irq: fix DEBUG_SHIRQ handling Mariusz Kozlowski reported lockdep's warning: > ================================= > [ 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: [] rtl8139_interrupt+0x27/0x46b [8139too] > {in-hardirq-W} state was registered at: > [] __lock_acquire+0x949/0x11ac > [] lock_acquire+0x99/0xb2 > [] _spin_lock+0x35/0x42 > [] rtl8139_interrupt+0x27/0x46b [8139too] > [] handle_IRQ_event+0x28/0x59 > [] handle_level_irq+0xad/0x10b > [] do_IRQ+0x93/0xd0 > [] common_interrupt+0x2e/0x34 ... > other info that might help us debug this: > 1 lock held by ifconfig/5492: > #0: (rtnl_mutex){--..}, at: [] mutex_lock+0x1c/0x1f > > stack backtrace: ... > [] _spin_lock+0x35/0x42 > [] rtl8139_interrupt+0x27/0x46b [8139too] > [] free_irq+0x11b/0x146 > [] rtl8139_close+0x8a/0x14a [8139too] > [] dev_close+0x57/0x74 ... This shows that a driver's irq handler was running both in hard interrupt and process contexts with irqs enabled. The latter was done during free_irq() call and was possible only with CONFIG_DEBUG_SHIRQ enabled. This was fixed by another patch. But similar problem is possible with request_irq(): any locks taken from irq handler could be vulnerable - especially with soft interrupts. This patch fixes it by disabling local interrupts during handler's run. (It seems, disabling softirqs should be enough, but it needs more checking on possible races or other special cases). Reported-by: Mariusz Kozlowski Signed-off-by: Jarek Poplawski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/irq/manage.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 853aefbd184b..7230d914eaa2 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -547,14 +547,11 @@ int request_irq(unsigned int irq, irq_handler_t handler, * 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