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authorFrederic Weisbecker <fweisbec@gmail.com>2016-03-24 15:37:59 +0100
committerIngo Molnar <mingo@kernel.org>2016-03-29 11:52:11 +0200
commit5acba71e18833b9d06686b3751598bfa263a3ac3 (patch)
tree31ad607ebf024af39acb6ff1a68947fb6c727f03 /include
parent1993b176a8224e371e0732ffada7ab9eb3b0912b (diff)
downloadlinux-sh-5acba71e18833b9d06686b3751598bfa263a3ac3.tar.gz
locking/atomic: Introduce atomic_fetch_or()
This is deemed to replace the type generic fetch_or() which brings a lot of issues such as macro induced block variable aliasing and sloppy types. Not to mention fetch_or() doesn't refer to any namespace, adding even more confusion. So lets provide an atomic_t version. Current and next users of fetch_or() are thus encouraged to use atomic_t. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1458830281-4255-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/atomic.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index df4f369254c0..3d64c0852164 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -559,6 +559,27 @@ static inline int atomic_dec_if_positive(atomic_t *v)
#endif
/**
+ * atomic_fetch_or - perform *p |= mask and return old value of *p
+ * @p: pointer to atomic_t
+ * @mask: mask to OR on the atomic_t
+ */
+#ifndef atomic_fetch_or
+static inline int atomic_fetch_or(atomic_t *p, int mask)
+{
+ int old, val = atomic_read(p);
+
+ for (;;) {
+ old = atomic_cmpxchg(p, val, val | mask);
+ if (old == val)
+ break;
+ val = old;
+ }
+
+ return old;
+}
+#endif
+
+/**
* fetch_or - perform *ptr |= mask and return old value of *ptr
* @ptr: pointer to value
* @mask: mask to OR on the value