From ff3da2e0938bae36d10d69c22bce0177b067a9e2 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 2 Apr 2008 15:58:40 +1100 Subject: [POWERPC] Fix iSeries hard irq enabling regression A subtle bug sneaked into iSeries recently. On this platform, we must not normally clear MSR:EE (the hardware external interrupt enable) except for short periods of time. Taking an interrupt while soft-disabled doesn't cause us to clear it for example. The iSeries kernel expects to mostly run with MSR:EE enabled at all times except in a few exception entry/exit code paths. Thus local_irq_enable() doesn't check if it needs to hard-enable as it expects this to be unnecessary on iSeries. However, hard_irq_disable() _does_ cause MSR:EE to be cleared, including on iSeries. A call to it was recently added to the context switch code, thus causing interrupts to become disabled for a long periods of time, causing the iSeries watchdog to kick in under some circumstances and other nasty things. This patch fixes it by making local_irq_enable() properly re-enable MSR:EE on iSeries. It basically removes a return statement here to make iSeries use the same code path as everybody else. That does mean that we might occasionally get spurious decrementer interrupts but I don't think that matters. Another option would have been to make hard_irq_disable() a nop on iSeries but I didn't like it much, in case we have good reasons to hard-disable. Part of the patch is fixes to make sure the hard_enabled PACA field is properly set on iSeries as it used not to be before, since it was mostly unused. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/irq.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/powerpc/kernel/irq.c') diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index b0e5deb4274f..292163f5b39a 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -143,7 +143,6 @@ void local_irq_restore(unsigned long en) */ if (local_paca->lppaca_ptr->int_dword.any_int) iseries_handle_interrupts(); - return; } /* -- cgit v1.2.3