locking/atomic, arch/blackfin: 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@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adi-buildroot-devel@lists.sourceforge.net
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 40 insertions, 12 deletions

diff --git a/arch/blackfin/include/asm/atomic.h b/arch/blackfin/include/asm/atomic.h
index 1c1c423..63c7dec 100644
--- a/arch/blackfin/include/asm/atomic.h
+++ b/arch/blackfin/include/asm/atomic.h
@@ -17,6 +17,7 @@
 
 asmlinkage int __raw_uncached_fetch_asm(const volatile int *ptr);
 asmlinkage int __raw_atomic_add_asm(volatile int *ptr, int value);
+asmlinkage int __raw_atomic_xadd_asm(volatile int *ptr, int value);
 
 asmlinkage int __raw_atomic_and_asm(volatile int *ptr, int value);
 asmlinkage int __raw_atomic_or_asm(volatile int *ptr, int value);
@@ -28,10 +29,17 @@ asmlinkage int __raw_atomic_test_asm(const volatile int *ptr, int value);
 #define atomic_add_return(i, v) __raw_atomic_add_asm(&(v)->counter, i)
 #define atomic_sub_return(i, v) __raw_atomic_add_asm(&(v)->counter, -(i))
 
+#define atomic_fetch_add(i, v) __raw_atomic_xadd_asm(&(v)->counter, i)
+#define atomic_fetch_sub(i, v) __raw_atomic_xadd_asm(&(v)->counter, -(i))
+
 #define atomic_or(i, v)  (void)__raw_atomic_or_asm(&(v)->counter, i)
 #define atomic_and(i, v) (void)__raw_atomic_and_asm(&(v)->counter, i)
 #define atomic_xor(i, v) (void)__raw_atomic_xor_asm(&(v)->counter, i)
 
+#define atomic_fetch_or(i, v)  __raw_atomic_or_asm(&(v)->counter, i)
+#define atomic_fetch_and(i, v) __raw_atomic_and_asm(&(v)->counter, i)
+#define atomic_fetch_xor(i, v) __raw_atomic_xor_asm(&(v)->counter, i)
+
 #endif
 
 #include <asm-generic/atomic.h>
diff --git a/arch/blackfin/kernel/bfin_ksyms.c b/arch/blackfin/kernel/bfin_ksyms.c
index a401c27..68096e8 100644
--- a/arch/blackfin/kernel/bfin_ksyms.c
+++ b/arch/blackfin/kernel/bfin_ksyms.c
@@ -84,6 +84,7 @@ EXPORT_SYMBOL(insl_16);
 
 #ifdef CONFIG_SMP
 EXPORT_SYMBOL(__raw_atomic_add_asm);
+EXPORT_SYMBOL(__raw_atomic_xadd_asm);
 EXPORT_SYMBOL(__raw_atomic_and_asm);
 EXPORT_SYMBOL(__raw_atomic_or_asm);
 EXPORT_SYMBOL(__raw_atomic_xor_asm);
diff --git a/arch/blackfin/mach-bf561/atomic.S b/arch/blackfin/mach-bf561/atomic.S
index 26fccb5..1e2989c 100644
--- a/arch/blackfin/mach-bf561/atomic.S
+++ b/arch/blackfin/mach-bf561/atomic.S
@@ -607,6 +607,28 @@ ENDPROC(___raw_atomic_add_asm)
 
 /*
  * r0 = ptr
+ * r1 = value
+ *
+ * ADD a signed value to a 32bit word and return the old value atomically.
+ * Clobbers: r3:0, p1:0
+ */
+ENTRY(___raw_atomic_xadd_asm)
+	p1 = r0;
+	r3 = r1;
+	[--sp] = rets;
+	call _get_core_lock;
+	r3 = [p1];
+	r2 = r3 + r2;
+	[p1] = r2;
+	r1 = p1;
+	call _put_core_lock;
+	r0 = r3;
+	rets = [sp++];
+	rts;
+ENDPROC(___raw_atomic_add_asm)
+
+/*
+ * r0 = ptr
  * r1 = mask
  *
  * AND the mask bits from a 32bit word and return the old 32bit value
@@ -618,10 +640,9 @@ ENTRY(___raw_atomic_and_asm)
 	r3 = r1;
 	[--sp] = rets;
 	call _get_core_lock;
-	r2 = [p1];
-	r3 = r2 & r3;
-	[p1] = r3;
-	r3 = r2;
+	r3 = [p1];
+	r2 = r2 & r3;
+	[p1] = r2;
 	r1 = p1;
 	call _put_core_lock;
 	r0 = r3;
@@ -642,10 +663,9 @@ ENTRY(___raw_atomic_or_asm)
 	r3 = r1;
 	[--sp] = rets;
 	call _get_core_lock;
-	r2 = [p1];
-	r3 = r2 | r3;
-	[p1] = r3;
-	r3 = r2;
+	r3 = [p1];
+	r2 = r2 | r3;
+	[p1] = r2;
 	r1 = p1;
 	call _put_core_lock;
 	r0 = r3;
@@ -666,10 +686,9 @@ ENTRY(___raw_atomic_xor_asm)
 	r3 = r1;
 	[--sp] = rets;
 	call _get_core_lock;
-	r2 = [p1];
-	r3 = r2 ^ r3;
-	[p1] = r3;
-	r3 = r2;
+	r3 = [p1];
+	r2 = r2 ^ r3;
+	[p1] = r2;
 	r1 = p1;
 	call _put_core_lock;
 	r0 = r3;