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| author | Uros Bizjak <ubizjak@gmail.com> | 2024-05-23 10:35:14 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-06-25 08:24:56 +0300 |
| commit | 47e39c79336760031f98215c014c9800f5ed6481 (patch) | |
| tree | 20851bdb3feb8b90a03e4f9eaac4a4ad1f462e9a /kernel | |
| parent | af77c4fc1871847b528d58b7fdafb4aa1f6a9262 (diff) | |
| download | linux-47e39c79336760031f98215c014c9800f5ed6481.tar.xz | |
fork: use this_cpu_try_cmpxchg() in try_release_thread_stack_to_cache()
Use this_cpu_try_cmpxchg() instead of this_cpu_cmpxchg (*ptr, old, new) ==
old in try_release_thread_stack_to_cache. x86 CMPXCHG instruction returns
success in ZF flag, so this change saves a compare after cmpxchg (and
related move instruction in front of cmpxchg).
No functional change intended.
[ubizjak@gmail.com: simplify the for loop a bit]
Link: https://lkml.kernel.org/r/20240523214442.21102-1-ubizjak@gmail.com
Link: https://lkml.kernel.org/r/20240523073530.8128-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/fork.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 99076dbe27d8..f1c16b3dd8ac 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -205,9 +205,10 @@ static bool try_release_thread_stack_to_cache(struct vm_struct *vm) unsigned int i; for (i = 0; i < NR_CACHED_STACKS; i++) { - if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL) - continue; - return true; + struct vm_struct *tmp = NULL; + + if (this_cpu_try_cmpxchg(cached_stacks[i], &tmp, vm)) + return true; } return false; } |