[PATCH 2/2] arm64: smp: Don't directly call arch_smp_send_reschedule() for wakeup

Douglas Anderson
2023-10-02T16:46:49Z

In commit 2b2d0a7a96ab ("arm64: smp: Remove dedicated wakeup IPI") we
started using a scheduler IPI to avoid a dedicated reschedule. When we
did this, we used arch_smp_send_reschedule() directly rather than
calling smp_send_reschedule(). The only difference is that calling
arch_smp_send_reschedule() directly avoids tracing. Presumably we
_don't_ want to avoid tracing here, so switch to
smp_send_reschedule().

Fixes: 2b2d0a7a96ab ("arm64: smp: Remove dedicated wakeup IPI")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
I don't 100% know if this is correct and I don't have any hardware
that uses the "ACPI parking protocol", but I think it's right. My main
incentive for this is that it makes it easier to backport pseudo-NMI
to kernels that don't have arch_smp_send_reschedule(), but I think
it's also more correct.

If for some reason we truly did want to avoid tracing here, please
shout and we can drop this patch.

arch/arm64/kernel/smp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 0a6002243a8c..b530d8ef9c1d 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -1063,7 +1063,7 @@ void arch_send_wakeup_ipi(unsigned int cpu)
* We use a scheduler IPI to wake the CPU as this avoids the need for a
* dedicated IPI and we can safely handle spurious scheduler IPIs.
*/
- arch_smp_send_reschedule(cpu);
+ smp_send_reschedule(cpu);
}
#endif

--
2.42.0.582.g8ccd20d70d-goog