path: root/arch/sh/atomic.h
diff options
authorRich Felker <>2014-08-25 15:43:40 -0400
committerRich Felker <>2014-08-25 15:43:40 -0400
commitea818ea8340c13742a4f41e6077f732291aea4bc (patch)
treef2a97e8f8a25fc3337002aa30bb235575593af86 /arch/sh/atomic.h
parent5345c9b884e7c4e73eb2c8bb83b8d0df20f95afb (diff)
add working a_spin() atomic for non-x86 targets
conceptually, a_spin needs to be at least a compiler barrier, so the compiler will not optimize out loops (and the load on each iteration) while spinning. it should also be a memory barrier, or the spinning thread might keep spinning without noticing stores from other threads, thus delaying for longer than it should. ideally, an optimal a_spin implementation that avoids unnecessary cache/memory contention should be chosen for each arch, but for now, the easiest thing is to perform a useless a_cas on the calling thread's stack.
Diffstat (limited to 'arch/sh/atomic.h')
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/sh/atomic.h b/arch/sh/atomic.h
index 93ab54fe..b95bbffc 100644
--- a/arch/sh/atomic.h
+++ b/arch/sh/atomic.h
@@ -53,6 +53,7 @@ static inline void a_dec(volatile int *x)
static inline void a_spin()
+ a_cas(&(int){0}, 0, 0);
static inline void a_crash()