Commit-ID: 4be7dd393515615430a4d07ca1ffceaf2a331620
Gitweb: http://git.kernel.org/tip/4be7dd393515615430a4d07ca1ffceaf2a331620
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 18 Apr 2016 01:16:07 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 16 Jun 2016 10:48:25 +0200
locking/atomic, arch/hexagon: Implement atomic_fetch_{add,sub,and,or,xor}()
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Richard Kuo <rkuo@xxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-hexagon@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/hexagon/include/asm/atomic.h | 33 ++++++++++++++++++++++++++++-----
1 file changed, 28 insertions(+), 5 deletions(-)
diff --git a/arch/hexagon/include/asm/atomic.h b/arch/hexagon/include/asm/atomic.h
index 55696c4..07dbb33 100644
--- a/arch/hexagon/include/asm/atomic.h
+++ b/arch/hexagon/include/asm/atomic.h
@@ -110,7 +110,7 @@ static inline void atomic_##op(int i, atomic_t *v) \
); \
} \
-#define ATOMIC_OP_RETURN(op) \
+#define ATOMIC_OP_RETURN(op) \
static inline int atomic_##op##_return(int i, atomic_t *v) \
{ \
int output; \
@@ -127,16 +127,39 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
return output; \
}
-#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
+#define ATOMIC_FETCH_OP(op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ int output, val; \
+ \
+ __asm__ __volatile__ ( \
+ "1: %0 = memw_locked(%2);\n" \
+ " %1 = "#op "(%0,%3);\n" \
+ " memw_locked(%2,P3)=%1;\n" \
+ " if !P3 jump 1b;\n" \
+ : "=&r" (output), "=&r" (val) \
+ : "r" (&v->counter), "r" (i) \
+ : "memory", "p3" \
+ ); \
+ return output; \
+}
+
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op)
ATOMIC_OPS(add)
ATOMIC_OPS(sub)
-ATOMIC_OP(and)
-ATOMIC_OP(or)
-ATOMIC_OP(xor)
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
+
+#define atomic_fetch_or atomic_fetch_or
+
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
--
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