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Subject[patch 04/15] Generic Mutex Subsystem, add-atomic-call-func-x86_64.patch

add two new atomic ops to x86_64: atomic_dec_call_if_negative() and
atomic_inc_call_if_nonpositive(), which are conditional-call-if atomic
operations. Needed by the new mutex code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

----

include/asm-x86_64/atomic.h | 56 ++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 56 insertions(+)

Index: linux/include/asm-x86_64/atomic.h
===================================================================
--- linux.orig/include/asm-x86_64/atomic.h
+++ linux/include/asm-x86_64/atomic.h
@@ -203,6 +203,62 @@ static __inline__ int atomic_sub_return(
#define atomic_inc_return(v) (atomic_add_return(1,v))
#define atomic_dec_return(v) (atomic_sub_return(1,v))

+/**
+ * atomic_dec_call_if_negative - decrement and call function if negative
+ * @v: pointer of type atomic_t
+ * @fn: function to call if the result is negative
+ *
+ * Atomically decrements @v and calls a function if the result is negative.
+ * NOTE: the function is type-checked and must be a fastcall.
+ */
+#define atomic_dec_call_if_negative(v, fn_name) \
+do { \
+ fastcall void (*__tmp)(atomic_t *) = fn_name; \
+ \
+ (void)__tmp; \
+ typecheck(atomic_t *, v); \
+ \
+ __asm__ __volatile__( \
+ LOCK "decl (%%rdi)\n" \
+ "js 2f\n" \
+ "1:\n" \
+ LOCK_SECTION_START("") \
+ "2: call "#fn_name"\n\t" \
+ "jmp 1b\n" \
+ LOCK_SECTION_END \
+ : \
+ :"D" (v) \
+ :"memory"); \
+} while (0)
+
+/**
+ * atomic_inc_call_if_nonpositive - increment and call function if nonpositive
+ * @v: pointer of type atomic_t
+ * @fn: function to call if the result is nonpositive
+ *
+ * Atomically increments @v and calls a function if the result is nonpositive.
+ * NOTE: the function is type-checked and must be a fastcall.
+ */
+#define atomic_inc_call_if_nonpositive(v, fn_name) \
+do { \
+ fastcall void (*__tmp)(atomic_t *) = fn_name; \
+ \
+ (void)__tmp; \
+ typecheck(atomic_t *, v); \
+ \
+ __asm__ __volatile__( \
+ LOCK "incl (%%rdi)\n" \
+ "jle 2f\n" \
+ "1:\n" \
+ LOCK_SECTION_START("") \
+ "2: call "#fn_name"\n\t" \
+ "jmp 1b\n" \
+ LOCK_SECTION_END \
+ : \
+ :"D" (v) \
+ :"memory"); \
+} while (0)
+
/* An 64bit atomic type */

typedef struct { volatile long counter; } atomic64_t;
-
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