alpha: Replace smp_read_barrier_depends() usage with smp_[r]mb()

In preparation for removing smp_read_barrier_depends() altogether,
move the Alpha code over to using smp_rmb() and smp_mb() directly.

Acked-by: Peter Zijlstra (Intel) <[e-mail]>
Acked-by: Paul E. McKenney <[e-mail]>
Signed-off-by: Will Deacon <[e-mail]>

arch/alpha/include/asm/atomic.h

···
 
 /*
  * To ensure dependency ordering is preserved for the _relaxed and
- * _release atomics, an smp_read_barrier_depends() is unconditionally
- * inserted into the _relaxed variants, which are used to build the
- * barriered versions. Avoid redundant back-to-back fences in the
- * _acquire and _fence versions.
+ * _release atomics, an smp_mb() is unconditionally inserted into the
+ * _relaxed variants, which are used to build the barriered versions.
+ * Avoid redundant back-to-back fences in the _acquire and _fence
+ * versions.
  */
 #define __atomic_acquire_fence()
 #define __atomic_post_full_fence()
···
 	".previous"							\
 	:"=&r" (temp), "=m" (v->counter), "=&r" (result)		\
 	:"Ir" (i), "m" (v->counter) : "memory");			\
-	smp_read_barrier_depends();					\
+	smp_mb();							\
 	return result;							\
 }
 
···
 	".previous"							\
 	:"=&r" (temp), "=m" (v->counter), "=&r" (result)		\
 	:"Ir" (i), "m" (v->counter) : "memory");			\
-	smp_read_barrier_depends();					\
+	smp_mb();							\
 	return result;							\
 }
 
···
 	".previous"							\
 	:"=&r" (temp), "=m" (v->counter), "=&r" (result)		\
 	:"Ir" (i), "m" (v->counter) : "memory");			\
-	smp_read_barrier_depends();					\
+	smp_mb();							\
 	return result;							\
 }
 
···
 	".previous"							\
 	:"=&r" (temp), "=m" (v->counter), "=&r" (result)		\
 	:"Ir" (i), "m" (v->counter) : "memory");			\
-	smp_read_barrier_depends();					\
+	smp_mb();							\
 	return result;							\
 }
 

arch/alpha/include/asm/pgtable.h

···
 extern inline pte_t pte_mkyoung(pte_t pte)	{ pte_val(pte) |= __ACCESS_BITS; return pte; }
 
 /*
- * The smp_read_barrier_depends() in the following functions are required to
- * order the load of *dir (the pointer in the top level page table) with any
- * subsequent load of the returned pmd_t *ret (ret is data dependent on *dir).
+ * The smp_rmb() in the following functions are required to order the load of
+ * *dir (the pointer in the top level page table) with any subsequent load of
+ * the returned pmd_t *ret (ret is data dependent on *dir).
  *
  * If this ordering is not enforced, the CPU might load an older value of
  * *ret, which may be uninitialized data. See mm/memory.c:__pte_alloc for
···
 extern inline pmd_t * pmd_offset(pud_t * dir, unsigned long address)
 {
 	pmd_t *ret = (pmd_t *) pud_page_vaddr(*dir) + ((address >> PMD_SHIFT) & (PTRS_PER_PAGE - 1));
-	smp_read_barrier_depends(); /* see above */
+	smp_rmb(); /* see above */
 	return ret;
 }
 #define pmd_offset pmd_offset
···
 {
 	pte_t *ret = (pte_t *) pmd_page_vaddr(*dir)
 		+ ((address >> PAGE_SHIFT) & (PTRS_PER_PAGE - 1));
-	smp_read_barrier_depends(); /* see above */
+	smp_rmb(); /* see above */
 	return ret;
 }
 #define pte_offset_kernel pte_offset_kernel

mm/memory.c

···
 	 * of a chain of data-dependent loads, meaning most CPUs (alpha
 	 * being the notable exception) will already guarantee loads are
 	 * seen in-order. See the alpha page table accessors for the
-	 * smp_read_barrier_depends() barriers in page table walking code.
+	 * smp_rmb() barriers in page table walking code.
 	 */
 	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */