Merge branches 'x86-rwsem-for-linus' and 'x86-gcc46-for-linus' of git…

…://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-rwsem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, rwsem: Minor cleanups
  x86, rwsem: Stay on fast path when count > 0 in __up_write()

* 'x86-gcc46-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, gcc-4.6: Fix set but not read variables
  x86, gcc-4.6: Avoid unused by set variables in rdmsr

arch/x86/include/asm/msr.h

@@ -148,8 +148,8 @@ static inline unsigned long long native_read_pmc(int counter)
 #define rdmsr(msr, val1, val2)					\
 do {								\
 	u64 __val = native_read_msr((msr));			\
-	(val1) = (u32)__val;					\
-	(val2) = (u32)(__val >> 32);				\
+	(void)((val1) = (u32)__val);				\
+	(void)((val2) = (u32)(__val >> 32));			\
 } while (0)
 
 static inline void wrmsr(unsigned msr, unsigned low, unsigned high)

arch/x86/include/asm/rwsem.h

@@ -118,7 +118,7 @@ static inline void __down_read(struct rw_semaphore *sem)
 {
 	asm volatile("# beginning down_read\n\t"
 		     LOCK_PREFIX _ASM_INC "(%1)\n\t"
-		     /* adds 0x00000001, returns the old value */
+		     /* adds 0x00000001 */
 		     "  jns        1f\n"
 		     "  call call_rwsem_down_read_failed\n"
 		     "1:\n\t"
@@ -156,19 +156,17 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
 static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 {
 	rwsem_count_t tmp;
-
-	tmp = RWSEM_ACTIVE_WRITE_BIAS;
 	asm volatile("# beginning down_write\n\t"
 		     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
-		     /* subtract 0x0000ffff, returns the old value */
+		     /* adds 0xffff0001, returns the old value */
 		     "  test      %1,%1\n\t"
 		     /* was the count 0 before? */
 		     "  jz        1f\n"
 		     "  call call_rwsem_down_write_failed\n"
 		     "1:\n"
 		     "# ending down_write"
 		     : "+m" (sem->count), "=d" (tmp)
-		     : "a" (sem), "1" (tmp)
+		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS)
 		     : "memory", "cc");
 }
 
@@ -195,16 +193,16 @@ static inline int __down_write_trylock(struct rw_semaphore *sem)
  */
 static inline void __up_read(struct rw_semaphore *sem)
 {
-	rwsem_count_t tmp = -RWSEM_ACTIVE_READ_BIAS;
+	rwsem_count_t tmp;
 	asm volatile("# beginning __up_read\n\t"
 		     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
 		     /* subtracts 1, returns the old value */
 		     "  jns        1f\n\t"
-		     "  call call_rwsem_wake\n"
+		     "  call call_rwsem_wake\n" /* expects old value in %edx */
 		     "1:\n"
 		     "# ending __up_read\n"
 		     : "+m" (sem->count), "=d" (tmp)
-		     : "a" (sem), "1" (tmp)
+		     : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS)
 		     : "memory", "cc");
 }
 
@@ -216,10 +214,9 @@ static inline void __up_write(struct rw_semaphore *sem)
 	rwsem_count_t tmp;
 	asm volatile("# beginning __up_write\n\t"
 		     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
-		     /* tries to transition
-			0xffff0001 -> 0x00000000 */
-		     "  jz       1f\n"
-		     "  call call_rwsem_wake\n"
+		     /* subtracts 0xffff0001, returns the old value */
+		     "  jns        1f\n\t"
+		     "  call call_rwsem_wake\n" /* expects old value in %edx */
 		     "1:\n\t"
 		     "# ending __up_write\n"
 		     : "+m" (sem->count), "=d" (tmp)

arch/x86/kernel/aperture_64.c

@@ -280,7 +280,7 @@ void __init early_gart_iommu_check(void)
 	 * or BIOS forget to put that in reserved.
 	 * try to update e820 to make that region as reserved.
 	 */
-	u32 agp_aper_base = 0, agp_aper_order = 0;
+	u32 agp_aper_order = 0;
 	int i, fix, slot, valid_agp = 0;
 	u32 ctl;
 	u32 aper_size = 0, aper_order = 0, last_aper_order = 0;
@@ -291,7 +291,7 @@ void __init early_gart_iommu_check(void)
 		return;
 
 	/* This is mostly duplicate of iommu_hole_init */
-	agp_aper_base = search_agp_bridge(&agp_aper_order, &valid_agp);
+	search_agp_bridge(&agp_aper_order, &valid_agp);
 
 	fix = 0;
 	for (i = 0; i < ARRAY_SIZE(bus_dev_ranges); i++) {

arch/x86/kernel/cpu/mtrr/generic.c

@@ -433,13 +433,12 @@ static void generic_get_mtrr(unsigned int reg, unsigned long *base,
 {
 	unsigned int mask_lo, mask_hi, base_lo, base_hi;
 	unsigned int tmp, hi;
-	int cpu;
 
 	/*
 	 * get_mtrr doesn't need to update mtrr_state, also it could be called
 	 * from any cpu, so try to print it out directly.
 	 */
-	cpu = get_cpu();
+	get_cpu();
 
 	rdmsr(MTRRphysMask_MSR(reg), mask_lo, mask_hi);