Recently lockless_dereference() was added which can be used in place of hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
I replaced the inline functions dereferencing pointer 'x' to use lockless_dereference() because of which we do not need to litter the code with smp_read_barrier_depends(). Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com> --- include/linux/assoc_array_priv.h | 11 +++++++---- lib/assoc_array.c | 7 ------- security/keys/keyring.c | 6 ------ 3 files changed, 7 insertions(+), 17 deletions(-) diff --git a/include/linux/assoc_array_priv.h b/include/linux/assoc_array_priv.h index 711275e..96449c3 100644 --- a/include/linux/assoc_array_priv.h +++ b/include/linux/assoc_array_priv.h @@ -118,7 +118,8 @@ struct assoc_array_edit { static inline bool assoc_array_ptr_is_meta(const struct assoc_array_ptr *x) { - return (unsigned long)x & ASSOC_ARRAY_PTR_TYPE_MASK; + return (unsigned long)lockless_dereference(x) & + ASSOC_ARRAY_PTR_TYPE_MASK; } static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x) { @@ -126,7 +127,8 @@ static inline bool assoc_array_ptr_is_leaf(const struct assoc_array_ptr *x) } static inline bool assoc_array_ptr_is_shortcut(const struct assoc_array_ptr *x) { - return (unsigned long)x & ASSOC_ARRAY_PTR_SUBTYPE_MASK; + return (unsigned long)lockless_dereference(x) & + ASSOC_ARRAY_PTR_SUBTYPE_MASK; } static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x) { @@ -135,13 +137,14 @@ static inline bool assoc_array_ptr_is_node(const struct assoc_array_ptr *x) static inline void *assoc_array_ptr_to_leaf(const struct assoc_array_ptr *x) { - return (void *)((unsigned long)x & ~ASSOC_ARRAY_PTR_TYPE_MASK); + return (void *)((unsigned long)lockless_dereference(x) & + ~ASSOC_ARRAY_PTR_TYPE_MASK); } static inline unsigned long __assoc_array_ptr_to_meta(const struct assoc_array_ptr *x) { - return (unsigned long)x & + return (unsigned long)lockless_dereference(x) & ~(ASSOC_ARRAY_PTR_SUBTYPE_MASK | ASSOC_ARRAY_PTR_TYPE_MASK); } static inline diff --git a/lib/assoc_array.c b/lib/assoc_array.c index 2404d03..5b62033 100644 --- a/lib/assoc_array.c +++ b/lib/assoc_array.c @@ -37,12 +37,10 @@ begin_node: if (assoc_array_ptr_is_shortcut(cursor)) { /* Descend through a shortcut */ shortcut = assoc_array_ptr_to_shortcut(cursor); - smp_read_barrier_depends(); cursor = ACCESS_ONCE(shortcut->next_node); } node = assoc_array_ptr_to_node(cursor); - smp_read_barrier_depends(); slot = 0; /* We perform two passes of each node. @@ -85,7 +83,6 @@ begin_node: continue_node: node = assoc_array_ptr_to_node(cursor); - smp_read_barrier_depends(); for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { ptr = ACCESS_ONCE(node->slots[slot]); @@ -104,7 +101,6 @@ finished_node: if (assoc_array_ptr_is_shortcut(parent)) { shortcut = assoc_array_ptr_to_shortcut(parent); - smp_read_barrier_depends(); cursor = parent; parent = ACCESS_ONCE(shortcut->back_pointer); slot = shortcut->parent_slot; @@ -215,7 +211,6 @@ jumped: consider_node: node = assoc_array_ptr_to_node(cursor); - smp_read_barrier_depends(); slot = segments >> (level & ASSOC_ARRAY_KEY_CHUNK_MASK); slot &= ASSOC_ARRAY_FAN_MASK; @@ -253,7 +248,6 @@ consider_node: cursor = ptr; follow_shortcut: shortcut = assoc_array_ptr_to_shortcut(cursor); - smp_read_barrier_depends(); pr_devel("shortcut to %d\n", shortcut->skip_to_level); sc_level = level + ASSOC_ARRAY_LEVEL_STEP; BUG_ON(sc_level > shortcut->skip_to_level); @@ -343,7 +337,6 @@ void *assoc_array_find(const struct assoc_array *array, * actually going to dereference it. */ leaf = assoc_array_ptr_to_leaf(ptr); - smp_read_barrier_depends(); if (ops->compare_object(leaf, index_key)) return (void *)leaf; } diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 8177010..48d3464 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -683,7 +683,6 @@ descend_to_keyring: * doesn't contain any keyring pointers. */ shortcut = assoc_array_ptr_to_shortcut(ptr); - smp_read_barrier_depends(); if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0) goto not_this_keyring; @@ -693,7 +692,6 @@ descend_to_keyring: } node = assoc_array_ptr_to_node(ptr); - smp_read_barrier_depends(); ptr = node->slots[0]; if (!assoc_array_ptr_is_meta(ptr)) @@ -706,7 +704,6 @@ descend_to_node: kdebug("descend"); if (assoc_array_ptr_is_shortcut(ptr)) { shortcut = assoc_array_ptr_to_shortcut(ptr); - smp_read_barrier_depends(); ptr = ACCESS_ONCE(shortcut->next_node); BUG_ON(!assoc_array_ptr_is_node(ptr)); } @@ -714,7 +711,6 @@ descend_to_node: begin_node: kdebug("begin_node"); - smp_read_barrier_depends(); slot = 0; ascend_to_node: /* Go through the slots in a node */ @@ -762,14 +758,12 @@ ascend_to_node: if (ptr && assoc_array_ptr_is_shortcut(ptr)) { shortcut = assoc_array_ptr_to_shortcut(ptr); - smp_read_barrier_depends(); ptr = ACCESS_ONCE(shortcut->back_pointer); slot = shortcut->parent_slot; } if (!ptr) goto not_this_keyring; node = assoc_array_ptr_to_node(ptr); - smp_read_barrier_depends(); slot++; /* If we've ascended to the root (zero backpointer), we must have just -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/