kernel/linux.git/include/asm-generic/rwonce.h, branch v6.6.131

asm/rwonce: Don't pull into 'asm-generic/rwonce.h'

2020-07-21T09:50:36+00:00

Now that 'smp_read_barrier_depends()' has gone the way of the Norwegian Blue, drop the inclusion of in 'asm-generic/rwonce.h'. This requires fixups to some architecture vdso headers which were previously relying on 'asm/barrier.h' coming in via 'linux/compiler.h'. Acked-by: Peter Zijlstra (Intel) Signed-off-by: Will Deacon

asm/rwonce: Remove smp_read_barrier_depends() invocation

2020-07-21T09:50:35+00:00

Alpha overrides __READ_ONCE() directly, so there's no need to use smp_read_barrier_depends() in the core code. This also means that __READ_ONCE() can be relied upon to provide dependency ordering. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon

asm/rwonce: Allow __READ_ONCE to be overridden by the architecture

2020-07-21T09:50:35+00:00

The meat and potatoes of READ_ONCE() is defined by the __READ_ONCE() macro, which uses a volatile casts in an attempt to avoid tearing of byte, halfword, word and double-word accesses. Allow this to be overridden by the architecture code in the case that things like memory barriers are also required. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon

compiler.h: Split {READ,WRITE}_ONCE definitions out into rwonce.h

2020-07-21T09:50:35+00:00

In preparation for allowing architectures to define their own implementation of the READ_ONCE() macro, move the generic {READ,WRITE}_ONCE() definitions out of the unwieldy 'linux/compiler.h' file and into a new 'rwonce.h' header under 'asm-generic'. Acked-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Signed-off-by: Will Deacon