Currently several architectures have kerneldoc comments for
arch_atomic_*(), which is unhelpful as these live in a shared namespace
where they clash, and the arch_atomic_*() ops are now an implementation
detail of the raw_atomic_*() ops, which no-one should use those
directly.
Delete the kerneldoc comments for arch_atomic_*(), along with
pseudo-kerneldoc comments which are in the correct style but are missing
the leading '/**' necessary to be true kerneldoc comments.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-28-mark.rutland@arm.com
Most architectures define the atomic/atomic64 xchg and cmpxchg
operations in terms of arch_xchg and arch_cmpxchg respectfully.
Add fallbacks for these cases and remove the trivial cases from arch
code. On some architectures the existing definitions are kept as these
are used to build other arch_atomic*() operations.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-5-mark.rutland@arm.com
The current ARC fetch/return atomics provide fully ordered semantics
only with 2 full barriers around the operation.
Instead implement them as relaxed variants without any barriers and
rely on generic code to generate the fully-ordered, acquire and release
varaints by adding the appropriate full barriers.
This helps elide some extra barriers in case of acquire/release/relaxed
calls.
bloat-o-meter for hsdk defconfig shows codegen improvements, although
numbers below inflated due to unrelated inlining heuristic changes
| bloat-o-meter vmlinux-643babe34fd7-non-relaxed vmlinux-45aa05cb44d7-relaxed
| add/remove: 2/5 grow/shrink: 42/1222 up/down: 4158/-14312 (-10154)
| Function old new delta
| ..
| sys_renameat 462 476 +14
| ip_mc_inc_group 424 436 +12
| do_read_cache_page 1882 1894 +12
| ..
| refcount_dec_and_mutex_lock 254 250 -4
| refcount_dec_and_lock_irqsave 258 254 -4
| refcount_dec_and_lock 254 250 -4
| ..
| tcp_v6_route_req 246 238 -8
| tcp_v4_destroy_sock 286 278 -8
| tcp_twsk_unique 352 344 -8
Link: https://lore.kernel.org/r/20180830144344.GW24142@hirez.programming.kicks-ass.net
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
