Commit-ID: 5acba71e18833b9d06686b3751598bfa263a3ac3
Gitweb: http://git.kernel.org/tip/5acba71e18833b9d06686b3751598bfa263a3ac3
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Thu, 24 Mar 2016 15:37:59 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 29 Mar 2016 11:52:11 +0200
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@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1458830281-4255-2-git-send-email-fweisbec@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/atomic.h | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index df4f369..3d64c08 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
--
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