locking/pvqspinlock: Use try_cmpxchg() in qspinlock_paravirt.h
authorUros Bizjak <ubizjak@gmail.com>
Thu, 11 Apr 2024 19:22:55 +0000 (21:22 +0200)
committerIngo Molnar <mingo@kernel.org>
Fri, 12 Apr 2024 09:42:39 +0000 (11:42 +0200)
commitfea0e1820b51fff95c85518eb9cf3386f367908d
treefc9ca71103216ce6200042036c59ba56e2b54713
parent6a97734f2222e0352f1900e3eb3167e9069b91bb
locking/pvqspinlock: Use try_cmpxchg() in qspinlock_paravirt.h

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

No functional change intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240411192317.25432-2-ubizjak@gmail.com
kernel/locking/qspinlock_paravirt.h