path: root/kernel
diff options
authorThomas Gleixner <tglx@linutronix.de>2011-02-18 23:27:23 +0100
committerThomas Gleixner <tglx@linutronix.de>2011-02-19 12:11:13 +0100
commit6d83f94db95cfe65d2a6359cccdf61cf087c2598 (patch)
treee685c8d43da6dec24901658905cf3cf08e127633 /kernel
parentc1ee6264280e740a9d3ff3feef38642cf0a57013 (diff)
genirq: Disable the SHIRQ_DEBUG call in request_threaded_irq for now
With CONFIG_SHIRQ_DEBUG=y we call a newly installed interrupt handler in request_threaded_irq(). The original implementation (commit a304e1b8) called the handler _BEFORE_ it was installed, but that caused problems with handlers calling disable_irq_nosync(). See commit 377bf1e4. It's braindead in the first place to call disable_irq_nosync in shared handlers, but .... Moving this call after we installed the handler looks innocent, but it is very subtle broken on SMP. Interrupt handlers rely on the fact, that the irq core prevents reentrancy. Now this debug call violates that promise because we run the handler w/o the IRQ_INPROGRESS protection - which we cannot apply here because that would result in a possibly forever masked interrupt line. A concurrent real hardware interrupt on a different CPU results in handler reentrancy and can lead to complete wreckage, which was unfortunately observed in reality and took a fricking long time to debug. Leave the code here for now. We want this debug feature, but that's not easy to fix. We really should get rid of those disable_irq_nosync() abusers and remove that function completely. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Anton Vorontsov <avorontsov@ru.mvista.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Arjan van de Ven <arjan@infradead.org> Cc: stable@kernel.org # .28 -> .37
Diffstat (limited to 'kernel')
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0caa59f747dd..9033c1c70828 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1100,7 +1100,7 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
if (retval)
if (!retval && (irqflags & IRQF_SHARED)) {
* It's a shared IRQ -- the driver ought to be prepared for it