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Subject[tip: locking/core] locking/atomic: atomic64: Remove unusable atomic ops
The following commit has been merged into the locking/core branch of tip:

Commit-ID: 5fb6e8cf53b005d287d4c2d137a415ff7d025a81
Gitweb: https://git.kernel.org/tip/5fb6e8cf53b005d287d4c2d137a415ff7d025a81
Author: Mark Rutland <mark.rutland@arm.com>
AuthorDate: Fri, 26 Nov 2021 11:59:23
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 13 Dec 2021 10:56:09 +01:00

locking/atomic: atomic64: Remove unusable atomic ops

The generic atomic64 implementation provides:

* atomic64_and_return()
* atomic64_or_return()
* atomic64_xor_return()

... but none of these exist in the standard atomic64 API as described by
scripts/atomic/atomics.tbl, and none of these have prototypes exposed by
<asm-generic/atomic64.h>.

The lkp kernel test robot noted this results in warnings when building with
W=1:

lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_and_return' [-Wmissing-prototypes]

lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_or_return' [-Wmissing-prototypes]

lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_xor_return' [-Wmissing-prototypes]

This appears to have been a thinko in commit:

28aa2bda2211f432 ("locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()")

... where we grouped add/sub separately from and/ox/xor, so that we could avoid
implementing _return forms for the latter group, but forgot to remove
ATOMIC64_OP_RETURN() for that group.

This doesn't cause any functional problem, but it's pointless to build code
which cannot be used. Remove the unusable code. This does not affect add/sub,
for which _return forms will still be built.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20211126115923.41489-1-mark.rutland@arm.com
---
lib/atomic64.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/lib/atomic64.c b/lib/atomic64.c
index 3df6539..caf8957 100644
--- a/lib/atomic64.c
+++ b/lib/atomic64.c
@@ -118,7 +118,6 @@ ATOMIC64_OPS(sub, -=)
#undef ATOMIC64_OPS
#define ATOMIC64_OPS(op, c_op) \
ATOMIC64_OP(op, c_op) \
- ATOMIC64_OP_RETURN(op, c_op) \
ATOMIC64_FETCH_OP(op, c_op)

ATOMIC64_OPS(and, &=)
@@ -127,7 +126,6 @@ ATOMIC64_OPS(xor, ^=)

#undef ATOMIC64_OPS
#undef ATOMIC64_FETCH_OP
-#undef ATOMIC64_OP_RETURN
#undef ATOMIC64_OP

s64 generic_atomic64_dec_if_positive(atomic64_t *v)
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