[patch 3/8] mutex subsystem, add atomic_*_call_if_*() to i386

Ingo Molnar
2005-12-21T15:56:14Z

add two new atomic ops to i386: 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-i386/atomic.h | 55 ++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 55 insertions(+)

Index: linux/include/asm-i386/atomic.h
===================================================================
--- linux.orig/include/asm-i386/atomic.h
+++ linux/include/asm-i386/atomic.h
@@ -240,6 +240,61 @@ 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.
+ */
+#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 (%%eax)\n" \
+ "js 2f\n" \
+ "1:\n" \
+ LOCK_SECTION_START("") \
+ "2: call "#fn_name"\n\t" \
+ "jmp 1b\n" \
+ LOCK_SECTION_END \
+ : \
+ :"a" (v) \
+ :"memory","cx","dx"); \
+} 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.
+ */
+#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 (%%eax)\n" \
+ "jle 2f\n" \
+ "1:\n" \
+ LOCK_SECTION_START("") \
+ "2: call "#fn_name"\n\t" \
+ "jmp 1b\n" \
+ LOCK_SECTION_END \
+ : \
+ :"a" (v) \
+ :"memory","cx","dx"); \
+} while (0)
+
+
/* These are x86-specific, used by some header files */
#define atomic_clear_mask(mask, addr) \
__asm__ __volatile__(LOCK "andl %0,%1" \