[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCHv2 1/4] atomic: replace atomic_compareandswap() with atomic_cmpxchg()
atomic_compareandswap() used atomic_t as the new, old and returned values which is less convinient than using just int. Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx> --- v2: - arm/arm64 already provided atomic_cmpxchg() --- xen/common/domain.c | 5 +---- xen/include/asm-arm/atomic.h | 8 -------- xen/include/asm-x86/atomic.h | 24 ++++++++++++++++-------- xen/include/xen/sched.h | 9 ++++----- 4 files changed, 21 insertions(+), 25 deletions(-) diff --git a/xen/common/domain.c b/xen/common/domain.c index 2979c1b..93e77f5 100644 --- a/xen/common/domain.c +++ b/xen/common/domain.c @@ -857,14 +857,11 @@ static void complete_domain_destroy(struct rcu_head *head) void domain_destroy(struct domain *d) { struct domain **pd; - atomic_t old = ATOMIC_INIT(0); - atomic_t new = ATOMIC_INIT(DOMAIN_DESTROYED); BUG_ON(!d->is_dying); /* May be already destroyed, or get_domain() can race us. */ - old = atomic_compareandswap(old, new, &d->refcnt); - if ( _atomic_read(old) != 0 ) + if ( atomic_cmpxchg(&d->refcnt, 0, DOMAIN_DESTROYED) != 0 ) return; cpupool_rm_domain(d); diff --git a/xen/include/asm-arm/atomic.h b/xen/include/asm-arm/atomic.h index 5a38c67..29ab265 100644 --- a/xen/include/asm-arm/atomic.h +++ b/xen/include/asm-arm/atomic.h @@ -138,14 +138,6 @@ static inline void _atomic_set(atomic_t *v, int i) # error "unknown ARM variant" #endif -static inline atomic_t atomic_compareandswap( - atomic_t old, atomic_t new, atomic_t *v) -{ - atomic_t rc; - rc.counter = __cmpxchg(&v->counter, old.counter, new.counter, sizeof(int)); - return rc; -} - #endif /* __ARCH_ARM_ATOMIC__ */ /* * Local variables: diff --git a/xen/include/asm-x86/atomic.h b/xen/include/asm-x86/atomic.h index 2b8c877..d246b70 100644 --- a/xen/include/asm-x86/atomic.h +++ b/xen/include/asm-x86/atomic.h @@ -135,6 +135,10 @@ static inline void _atomic_set(atomic_t *v, int i) v->counter = i; } +static inline int atomic_cmpxchg(atomic_t *v, int old, int new) +{ + return cmpxchg(&v->counter, old, new); +} /** * atomic_add - add integer to atomic variable @@ -152,6 +156,18 @@ static inline void atomic_add(int i, atomic_t *v) } /** + * atomic_add_return - add integer and return + * @i: integer value to add + * @v: pointer of type atomic_t + * + * Atomically adds @i to @v and returns @i + @v + */ +static inline int atomic_add_return(int i, atomic_t *v) +{ + return i + arch_fetch_and_add(&v->counter, i); +} + +/** * atomic_sub - subtract the atomic variable * @i: integer value to subtract * @v: pointer of type atomic_t @@ -272,12 +288,4 @@ static inline int atomic_add_negative(int i, atomic_t *v) return c; } -static inline atomic_t atomic_compareandswap( - atomic_t old, atomic_t new, atomic_t *v) -{ - atomic_t rc; - rc.counter = __cmpxchg(&v->counter, old.counter, new.counter, sizeof(int)); - return rc; -} - #endif /* __ARCH_X86_ATOMIC__ */ diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h index 82b6dd1..5870745 100644 --- a/xen/include/xen/sched.h +++ b/xen/include/xen/sched.h @@ -483,16 +483,15 @@ extern struct vcpu *idle_vcpu[NR_CPUS]; */ static always_inline int get_domain(struct domain *d) { - atomic_t old, new, seen = d->refcnt; + int old, seen = atomic_read(&d->refcnt); do { old = seen; - if ( unlikely(_atomic_read(old) & DOMAIN_DESTROYED) ) + if ( unlikely(old & DOMAIN_DESTROYED) ) return 0; - _atomic_set(&new, _atomic_read(old) + 1); - seen = atomic_compareandswap(old, new, &d->refcnt); + seen = atomic_cmpxchg(&d->refcnt, old, old + 1); } - while ( unlikely(_atomic_read(seen) != _atomic_read(old)) ); + while ( unlikely(seen != old) ); return 1; } -- 2.1.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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