Re: [PATCH 3/3] Improve robustness of the UIC cascade handler
From: Josh Boyer <hidden>
Date: 2007-08-15 19:26:49
On Tue, 14 Aug 2007 13:52:42 +1000 (EST) David Gibson [off-list ref] wrote:
quoted hunk ↗ jump to hunk
At present the cascade interrupt handler for the UIC (interrupt controller on 4xx embedded chips) will misbehave badly if it is called spuriously - that is if the handler is invoked when no interrupts are asserted in the child UIC. Although spurious interrupts shouldn't happen, it's good to behave robustly if they do. This patch does so by checking for and ignoring spurious interrupts. Signed-off-by: Valentine Barshak <redacted> Signed-off-by: David Gibson <redacted> --- arch/powerpc/sysdev/uic.c | 3 +++ 1 file changed, 3 insertions(+) Index: working-2.6/arch/powerpc/sysdev/uic.c ===================================================================--- working-2.6.orig/arch/powerpc/sysdev/uic.c 2007-08-14 13:46:02.000000000 +1000 +++ working-2.6/arch/powerpc/sysdev/uic.c 2007-08-14 13:46:02.000000000 +1000@@ -266,6 +266,9 @@ irqreturn_t uic_cascade(int virq, void * int subvirq; msr = mfdcr(uic->dcrbase + UIC_MSR); + if (!msr) /* spurious interrupt */ + return IRQ_HANDLED;
Hm. Is there was a way we could have this case increment ppc_spurious_interrupts so that the BAD entry in /proc/interrupts would be updated with these? Not a huge deal, but it might be nice to have. Otherwise the patch looks fine. Acked-by: Josh Boyer <redacted> josh