From: Junru Shen <hhusjrsjr@gmail.com>
To: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, Junru Shen <hhusjrsjr@gmail.com>
Subject: [PATCH] atomic: Put the fetching of the old value into the loop when doing atomic CAS
Date: Thu, 24 Feb 2022 16:24:38 +0800 [thread overview]
Message-ID: <20220224082438.580191-1-hhusjrsjr@gmail.com> (raw)
Put the acquisition of the expected value inside the loop to prevent an infinite loop when it does not match.
Signed-off-by: Junru Shen <hhusjrsjr@gmail.com>
---
arch/x86/include/asm/atomic64_64.h | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h
index 7886d0578..3df04c44c 100644
--- a/arch/x86/include/asm/atomic64_64.h
+++ b/arch/x86/include/asm/atomic64_64.h
@@ -207,9 +207,10 @@ static inline void arch_atomic64_and(s64 i, atomic64_t *v)
static inline s64 arch_atomic64_fetch_and(s64 i, atomic64_t *v)
{
- s64 val = arch_atomic64_read(v);
+ s64 val;
do {
+ val = arch_atomic64_read(v);
} while (!arch_atomic64_try_cmpxchg(v, &val, val & i));
return val;
}
@@ -225,9 +226,10 @@ static inline void arch_atomic64_or(s64 i, atomic64_t *v)
static inline s64 arch_atomic64_fetch_or(s64 i, atomic64_t *v)
{
- s64 val = arch_atomic64_read(v);
+ s64 val;
do {
+ val = arch_atomic64_read(v);
} while (!arch_atomic64_try_cmpxchg(v, &val, val | i));
return val;
}
@@ -243,9 +245,10 @@ static inline void arch_atomic64_xor(s64 i, atomic64_t *v)
static inline s64 arch_atomic64_fetch_xor(s64 i, atomic64_t *v)
{
- s64 val = arch_atomic64_read(v);
+ s64 val;
do {
+ val = arch_atomic64_read(v);
} while (!arch_atomic64_try_cmpxchg(v, &val, val ^ i));
return val;
}
--
2.30.2
next reply other threads:[~2022-02-24 8:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-24 8:24 Junru Shen [this message]
2022-02-24 10:13 ` Boqun Feng
2022-02-24 10:27 ` Mark Rutland
2022-02-24 12:02 ` Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2022-02-24 8:24 Junru Shen
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