llist: use try_cmpxchg in llist_add_batch and llist_del_first

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Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
llist_add_batch and llist_del_first.  x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after cmpxchg.

Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg
fails, enabling further code simplifications.

No functional change intended.

Link: https://lkml.kernel.org/r/20220712144917.4497-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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Uros Bizjak 2022-07-12 16:49:17 +02:00 • committed by Andrew Morton

parent 05c6257433

commit 4f1d2a030d

1 changed files with 4 additions and 8 deletions

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lib/llist.c

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