Commit 1cfc63b5 authored by Will Deacon's avatar Will Deacon Committed by Catalin Marinas

arm64: cmpwait: Clear event register before arming exclusive monitor

When waiting for a cacheline to change state in cmpwait, we may immediately
wake-up the first time around the outer loop if the event register was
already set (for example, because of the event stream).

Avoid these spurious wakeups by explicitly clearing the event register
before loading the cacheline and setting the exclusive monitor.
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent e75bef2a
......@@ -204,6 +204,8 @@ static inline void __cmpwait_case_##name(volatile void *ptr, \
unsigned long tmp; \
\
asm volatile( \
" sevl\n" \
" wfe\n" \
" ldxr" #sz "\t%" #w "[tmp], %[v]\n" \
" eor %" #w "[tmp], %" #w "[tmp], %" #w "[val]\n" \
" cbnz %" #w "[tmp], 1f\n" \
......
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