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authorMichael Ellerman <mpe@ellerman.id.au>2017-09-29 06:58:02 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2017-10-06 12:03:08 +0300
commitc6baa077b784c3b37391a8c11f433e3f881a80df (patch)
tree67ddf1598ce2d7a8004cf2b982bbfe0b29cd09fd /arch/powerpc/platforms/powernv/opal-irqchip.c
parent3368f5699a9b0e281e14f9f93244da0a922f6df0 (diff)
downloadlinux-c6baa077b784c3b37391a8c11f433e3f881a80df.tar.xz
powerpc/powernv: Make opal_event_shutdown() callable from IRQ context
In opal_event_shutdown() we free all the IRQs hanging off the opal_event_irqchip. However it's not safe to do so if we're called from IRQ context, because free_irq() wants to synchronise versus IRQ context. This can lead to warnings and a stuck system. For example from sysrq-b: Trying to free IRQ 17 from IRQ context! ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/irq/manage.c:1461 __free_irq+0x398/0x8d0 ... NIP __free_irq+0x398/0x8d0 LR __free_irq+0x394/0x8d0 Call Trace: __free_irq+0x394/0x8d0 (unreliable) free_irq+0xa4/0x140 opal_event_shutdown+0x128/0x180 opal_shutdown+0x1c/0xb0 pnv_shutdown+0x20/0x40 machine_restart+0x38/0x90 emergency_restart+0x28/0x40 sysrq_handle_reboot+0x24/0x40 __handle_sysrq+0x198/0x590 hvc_poll+0x48c/0x8c0 hvc_handle_interrupt+0x1c/0x50 __handle_irq_event_percpu+0xe8/0x6e0 handle_irq_event_percpu+0x34/0xe0 handle_irq_event+0xc4/0x210 handle_level_irq+0x250/0x770 generic_handle_irq+0x5c/0xa0 opal_handle_events+0x11c/0x240 opal_interrupt+0x38/0x50 __handle_irq_event_percpu+0xe8/0x6e0 handle_irq_event_percpu+0x34/0xe0 handle_irq_event+0xc4/0x210 handle_fasteoi_irq+0x174/0xa10 generic_handle_irq+0x5c/0xa0 __do_irq+0xbc/0x4e0 call_do_irq+0x14/0x24 do_IRQ+0x18c/0x540 hardware_interrupt_common+0x158/0x180 We can avoid that by using disable_irq_nosync() rather than free_irq(). Although it doesn't fully free the IRQ, it should be sufficient when we're shutting down, particularly in an emergency. Add an in_interrupt() check and use free_irq() when we're shutting down normally. It's probably OK to use disable_irq_nosync() in that case too, but for now it's safer to leave that behaviour as-is. Fixes: 9f0fd0499d30 ("powerpc/powernv: Add a virtual irqchip for opal events") Reported-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/platforms/powernv/opal-irqchip.c')
-rw-r--r--arch/powerpc/platforms/powernv/opal-irqchip.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-irqchip.c b/arch/powerpc/platforms/powernv/opal-irqchip.c
index ecdcba9d1220..9d1b8c0aaf93 100644
--- a/arch/powerpc/platforms/powernv/opal-irqchip.c
+++ b/arch/powerpc/platforms/powernv/opal-irqchip.c
@@ -174,8 +174,14 @@ void opal_event_shutdown(void)
/* First free interrupts, which will also mask them */
for (i = 0; i < opal_irq_count; i++) {
- if (opal_irqs[i])
+ if (!opal_irqs[i])
+ continue;
+
+ if (in_interrupt())
+ disable_irq_nosync(opal_irqs[i]);
+ else
free_irq(opal_irqs[i], NULL);
+
opal_irqs[i] = 0;
}
}