diff options
author | Peter Zijlstra <peterz@infradead.org> | 2017-02-01 18:07:55 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2017-03-23 10:54:41 +0300 |
commit | b78c0d471255e99411d6c1b3975df21c3cd9f349 (patch) | |
tree | 799156a3c194a43bcfe79f34a5d921f526f97103 /lib | |
parent | a9ebf306f52c756c4f9e50ee9a60cd6389d71344 (diff) |
locking/refcounts: Use atomic_try_cmpxchg()
Generates better code (GCC-6.2.1):
text filename
1576 defconfig-build/lib/refcount.o.pre
1488 defconfig-build/lib/refcount.o.post
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/refcount.c | 47 |
1 files changed, 15 insertions, 32 deletions
diff --git a/lib/refcount.c b/lib/refcount.c index 8e206ce5609b..f42124ccf295 100644 --- a/lib/refcount.c +++ b/lib/refcount.c @@ -57,9 +57,9 @@ */ bool refcount_add_not_zero(unsigned int i, refcount_t *r) { - unsigned int old, new, val = atomic_read(&r->refs); + unsigned int new, val = atomic_read(&r->refs); - for (;;) { + do { if (!val) return false; @@ -69,12 +69,8 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r) new = val + i; if (new < val) new = UINT_MAX; - old = atomic_cmpxchg_relaxed(&r->refs, val, new); - if (old == val) - break; - val = old; - } + } while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new)); WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); @@ -118,9 +114,9 @@ EXPORT_SYMBOL_GPL(refcount_add); */ bool refcount_inc_not_zero(refcount_t *r) { - unsigned int old, new, val = atomic_read(&r->refs); + unsigned int new, val = atomic_read(&r->refs); - for (;;) { + do { new = val + 1; if (!val) @@ -129,12 +125,7 @@ bool refcount_inc_not_zero(refcount_t *r) if (unlikely(!new)) return true; - old = atomic_cmpxchg_relaxed(&r->refs, val, new); - if (old == val) - break; - - val = old; - } + } while (!atomic_try_cmpxchg_relaxed(&r->refs, &val, new)); WARN_ONCE(new == UINT_MAX, "refcount_t: saturated; leaking memory.\n"); @@ -182,9 +173,9 @@ EXPORT_SYMBOL_GPL(refcount_inc); */ bool refcount_sub_and_test(unsigned int i, refcount_t *r) { - unsigned int old, new, val = atomic_read(&r->refs); + unsigned int new, val = atomic_read(&r->refs); - for (;;) { + do { if (unlikely(val == UINT_MAX)) return false; @@ -194,12 +185,7 @@ bool refcount_sub_and_test(unsigned int i, refcount_t *r) return false; } - old = atomic_cmpxchg_release(&r->refs, val, new); - if (old == val) - break; - - val = old; - } + } while (!atomic_try_cmpxchg_release(&r->refs, &val, new)); return !new; } @@ -258,7 +244,9 @@ EXPORT_SYMBOL_GPL(refcount_dec); */ bool refcount_dec_if_one(refcount_t *r) { - return atomic_cmpxchg_release(&r->refs, 1, 0) == 1; + int val = 1; + + return atomic_try_cmpxchg_release(&r->refs, &val, 0); } EXPORT_SYMBOL_GPL(refcount_dec_if_one); @@ -275,9 +263,9 @@ EXPORT_SYMBOL_GPL(refcount_dec_if_one); */ bool refcount_dec_not_one(refcount_t *r) { - unsigned int old, new, val = atomic_read(&r->refs); + unsigned int new, val = atomic_read(&r->refs); - for (;;) { + do { if (unlikely(val == UINT_MAX)) return true; @@ -290,12 +278,7 @@ bool refcount_dec_not_one(refcount_t *r) return true; } - old = atomic_cmpxchg_release(&r->refs, val, new); - if (old == val) - break; - - val = old; - } + } while (!atomic_try_cmpxchg_release(&r->refs, &val, new)); return true; } |