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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: 9f0fd0499d
("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>
This commit is contained in:
parent
3368f5699a
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c6baa077b7
@ -174,8 +174,14 @@ void opal_event_shutdown(void)
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/* First free interrupts, which will also mask them */
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for (i = 0; i < opal_irq_count; i++) {
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if (opal_irqs[i])
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if (!opal_irqs[i])
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continue;
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if (in_interrupt())
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disable_irq_nosync(opal_irqs[i]);
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else
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free_irq(opal_irqs[i], NULL);
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opal_irqs[i] = 0;
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}
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}
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