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author | Uros Bizjak <ubizjak@gmail.com> | 2023-01-16 19:34:46 +0300 |
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committer | Ingo Molnar <mingo@kernel.org> | 2023-01-26 13:49:39 +0300 |
commit | 50fd4d5e6914b60ea6f89c2cbff7a07799414c62 (patch) | |
tree | 1b0fb8d3451fa4917a7b64207f0b1527eb4a8572 /arch/x86/mm/Makefile | |
parent | 1d61659ced6bd8881cf2fb5cbcb28f9541fc7430 (diff) | |
download | linux-50fd4d5e6914b60ea6f89c2cbff7a07799414c62.tar.xz |
x86/PAT: Use try_cmpxchg() in set_page_memtype()
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
set_page_memtype. x86 CMPXCHG instruction returns success in ZF flag,
so this change saves a compare after cmpxchg (and related move
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>
Link: https://lore.kernel.org/r/20230116163446.4734-1-ubizjak@gmail.com
Diffstat (limited to 'arch/x86/mm/Makefile')
0 files changed, 0 insertions, 0 deletions