From: Uros Bizjak <ubizjak@gmail.com>
To: kexec@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: Uros Bizjak <ubizjak@gmail.com>, Eric Biederman <ebiederm@xmission.com>
Subject: [PATCH] kexec: Use atomic_try_cmpxchg_acquire() in kexec_trylock()
Date: Fri, 19 Jul 2024 12:38:52 +0200 [thread overview]
Message-ID: <20240719103937.53742-1-ubizjak@gmail.com> (raw)
Use atomic_try_cmpxchg_acquire(*ptr, &old, new) instead of
atomic_cmpxchg_acquire(*ptr, old, new) == old in kexec_trylock().
x86 CMPXCHG instruction returns success in ZF flag, so
this change saves a compare after cmpxchg.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Eric Biederman <ebiederm@xmission.com>
---
kernel/kexec_internal.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 2595defe8c0d..d35d9792402d 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -23,7 +23,8 @@ int kimage_is_destination_range(struct kimage *image,
extern atomic_t __kexec_lock;
static inline bool kexec_trylock(void)
{
- return atomic_cmpxchg_acquire(&__kexec_lock, 0, 1) == 0;
+ int old = 0;
+ return atomic_try_cmpxchg_acquire(&__kexec_lock, &old, 1);
}
static inline void kexec_unlock(void)
{
--
2.42.0
next reply other threads:[~2024-07-19 10:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-19 10:38 Uros Bizjak [this message]
2024-07-22 3:09 ` [PATCH] kexec: Use atomic_try_cmpxchg_acquire() in kexec_trylock() Baoquan He
2024-07-22 8:53 ` Uros Bizjak
2024-07-22 10:30 ` Baoquan He
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240719103937.53742-1-ubizjak@gmail.com \
--to=ubizjak@gmail.com \
--cc=ebiederm@xmission.com \
--cc=kexec@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox