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| author |   Michael Ellerman <mpe@ellerman.id.au> | 2017-09-29 13:58:02 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-10-06 20:03:08 +1100 |
| commit | c6baa077b784c3b37391a8c11f433e3f881a80df (patch) | |
| tree | 67ddf1598ce2d7a8004cf2b982bbfe0b29cd09fd | |
| parent | powerpc/jprobes: Validate break handler invocation as being due to a jprobe_return() (diff) | |
| download | linux-dev-c6baa077b784c3b37391a8c11f433e3f881a80df.tar.xz linux-dev-c6baa077b784c3b37391a8c11f433e3f881a80df.zip | |
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>
| -rw-r--r-- | arch/powerpc/platforms/powernv/opal-irqchip.c | 8 |
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; } } |