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author | Uros Bizjak <ubizjak@gmail.com> | 2023-01-16 17:25:22 +0100 |
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committer | Ingo Molnar <mingo@kernel.org> | 2023-01-26 11:49:40 +0100 |
commit | 890a0794b34f89fcd90e94ec970ad2bc18b70e73 (patch) | |
tree | 480c766e1b0e3405e6792293d569199fa9d8f3f8 /include/linux/lockdep.h | |
parent | 50fd4d5e6914b60ea6f89c2cbff7a07799414c62 (diff) | |
download | linux-890a0794b34f89fcd90e94ec970ad2bc18b70e73.tar.gz linux-890a0794b34f89fcd90e94ec970ad2bc18b70e73.tar.bz2 linux-890a0794b34f89fcd90e94ec970ad2bc18b70e73.zip |
x86/ACPI/boot: Use try_cmpxchg() in __acpi_{acquire,release}_global_lock()
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
__acpi_{acquire,release}_global_lock(). x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after CMPXCHG
(and related MOV instruction in front of CMPXCHG).
Also, try_cmpxchg() implicitly assigns old *ptr value to "old" when CMPXCHG
fails. There is no need to re-read the value in the loop.
Note that the value from *ptr should be read using READ_ONCE() to prevent
the compiler from merging, refetching or reordering the read.
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20230116162522.4072-1-ubizjak@gmail.com
Diffstat (limited to 'include/linux/lockdep.h')
0 files changed, 0 insertions, 0 deletions