[PATCH 5.8 397/633] powerpc/64: fix irq replay missing preempt

Greg Kroah-Hartman
2020-10-27T15:13:41Z

From: Nicholas Piggin <npiggin@gmail.com>

[ Upstream commit 903fd31d3212ab72d564c68f6cfb5d04db68773e ]

Prior to commit 3282a3da25bd ("powerpc/64: Implement soft interrupt
replay in C"), replayed interrupts returned by the regular interrupt
exit code, which performs preemption in case an interrupt had set
need_resched.

This logic was missed by the conversion. Adding preempt_disable/enable
around the interrupt replay and final irq enable will reschedule if
needed.

Fixes: 3282a3da25bd ("powerpc/64: Implement soft interrupt replay in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200915114650.3980244-1-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/kernel/irq.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 05b1cc0e009e4..297ee79febc6c 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -368,6 +368,12 @@ notrace void arch_local_irq_restore(unsigned long mask)
}
}

+ /*
+ * Disable preempt here, so that the below preempt_enable will
+ * perform resched if required (a replayed interrupt may set
+ * need_resched).
+ */
+ preempt_disable();
irq_soft_mask_set(IRQS_ALL_DISABLED);
trace_hardirqs_off();

@@ -377,6 +383,7 @@ notrace void arch_local_irq_restore(unsigned long mask)
trace_hardirqs_on();
irq_soft_mask_set(IRQS_ENABLED);
__hard_irq_enable();
+ preempt_enable();
}
EXPORT_SYMBOL(arch_local_irq_restore);

--
2.25.1