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authorMark Rutland <mark.rutland@arm.com>2018-06-21 15:13:17 +0300
committerIngo Molnar <mingo@kernel.org>2018-06-21 15:25:24 +0300
commit356701329fb391184618eda7b7fb68cb35271506 (patch)
tree4d9dc75f1a20215b12ec4f5c40870de290264484 /include/linux/atomic.h
parent2b523f170e399b0e1c8eec2c4b5889735b0d2b9b (diff)
downloadlinux-356701329fb391184618eda7b7fb68cb35271506.tar.xz
atomics/treewide: Make atomic64_fetch_add_unless() optional
Architectures with atomic64_fetch_add_unless() provide a preprocessor symbol if they do so, and all other architectures have trivial C implementations of atomic64_add_unless() which are near-identical. Let's unify the trivial definitions of atomic64_fetch_add_unless() in <linux/atomic.h>, so that we always have both atomic64_fetch_add_unless() and atomic64_add_unless() with less boilerplate code. This means that atomic64_add_unless() is always implemented in core code, and the instrumented atomics are updated accordingly. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/20180621121321.4761-15-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/atomic.h')
-rw-r--r--include/linux/atomic.h26
1 files changed, 24 insertions, 2 deletions
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 3c03de648007..530562ac7909 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -1043,6 +1043,30 @@ static inline int atomic_dec_if_positive(atomic_t *v)
#endif /* atomic64_try_cmpxchg */
/**
+ * atomic64_fetch_add_unless - add unless the number is already a given value
+ * @v: pointer of type atomic64_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, if @v was not already @u.
+ * Returns the original value of @v.
+ */
+#ifndef atomic64_fetch_add_unless
+static inline long long atomic64_fetch_add_unless(atomic64_t *v, long long a,
+ long long u)
+{
+ long long c = atomic64_read(v);
+
+ do {
+ if (unlikely(c == u))
+ break;
+ } while (!atomic64_try_cmpxchg(v, &c, c + a));
+
+ return c;
+}
+#endif
+
+/**
* atomic64_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
@@ -1051,12 +1075,10 @@ static inline int atomic_dec_if_positive(atomic_t *v)
* Atomically adds @a to @v, if @v was not already @u.
* Returns true if the addition was done.
*/
-#ifdef atomic64_fetch_add_unless
static inline bool atomic64_add_unless(atomic64_t *v, long long a, long long u)
{
return atomic64_fetch_add_unless(v, a, u) != u;
}
-#endif
/**
* atomic64_inc_not_zero - increment unless the number is zero