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authorMark Rutland <mark.rutland@arm.com>2017-10-23 14:07:29 -0700
committerIngo Molnar <mingo@kernel.org>2017-10-25 11:01:08 +0200
commit6aa7de059173a986114ac43b8f50b297a86f09a8 (patch)
tree77666afe795e022914ca26433d61686c694dc4fd /lib
parentb03a0fe0c5e4b46dcd400d27395b124499554a71 (diff)
download96b-common-6aa7de059173a986114ac43b8f50b297a86f09a8.tar.gz
locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()
Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/assoc_array.c20
-rw-r--r--lib/dynamic_queue_limits.c2
-rw-r--r--lib/llist.c2
-rw-r--r--lib/vsprintf.c4
4 files changed, 14 insertions, 14 deletions
diff --git a/lib/assoc_array.c b/lib/assoc_array.c
index 155c55d8db5f..fe7953aead82 100644
--- a/lib/assoc_array.c
+++ b/lib/assoc_array.c
@@ -39,7 +39,7 @@ begin_node:
/* Descend through a shortcut */
shortcut = assoc_array_ptr_to_shortcut(cursor);
smp_read_barrier_depends();
- cursor = ACCESS_ONCE(shortcut->next_node);
+ cursor = READ_ONCE(shortcut->next_node);
}
node = assoc_array_ptr_to_node(cursor);
@@ -55,7 +55,7 @@ begin_node:
*/
has_meta = 0;
for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
- ptr = ACCESS_ONCE(node->slots[slot]);
+ ptr = READ_ONCE(node->slots[slot]);
has_meta |= (unsigned long)ptr;
if (ptr && assoc_array_ptr_is_leaf(ptr)) {
/* We need a barrier between the read of the pointer
@@ -89,7 +89,7 @@ continue_node:
smp_read_barrier_depends();
for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
- ptr = ACCESS_ONCE(node->slots[slot]);
+ ptr = READ_ONCE(node->slots[slot]);
if (assoc_array_ptr_is_meta(ptr)) {
cursor = ptr;
goto begin_node;
@@ -98,7 +98,7 @@ continue_node:
finished_node:
/* Move up to the parent (may need to skip back over a shortcut) */
- parent = ACCESS_ONCE(node->back_pointer);
+ parent = READ_ONCE(node->back_pointer);
slot = node->parent_slot;
if (parent == stop)
return 0;
@@ -107,7 +107,7 @@ finished_node:
shortcut = assoc_array_ptr_to_shortcut(parent);
smp_read_barrier_depends();
cursor = parent;
- parent = ACCESS_ONCE(shortcut->back_pointer);
+ parent = READ_ONCE(shortcut->back_pointer);
slot = shortcut->parent_slot;
if (parent == stop)
return 0;
@@ -147,7 +147,7 @@ int assoc_array_iterate(const struct assoc_array *array,
void *iterator_data),
void *iterator_data)
{
- struct assoc_array_ptr *root = ACCESS_ONCE(array->root);
+ struct assoc_array_ptr *root = READ_ONCE(array->root);
if (!root)
return 0;
@@ -194,7 +194,7 @@ assoc_array_walk(const struct assoc_array *array,
pr_devel("-->%s()\n", __func__);
- cursor = ACCESS_ONCE(array->root);
+ cursor = READ_ONCE(array->root);
if (!cursor)
return assoc_array_walk_tree_empty;
@@ -220,7 +220,7 @@ consider_node:
slot = segments >> (level & ASSOC_ARRAY_KEY_CHUNK_MASK);
slot &= ASSOC_ARRAY_FAN_MASK;
- ptr = ACCESS_ONCE(node->slots[slot]);
+ ptr = READ_ONCE(node->slots[slot]);
pr_devel("consider slot %x [ix=%d type=%lu]\n",
slot, level, (unsigned long)ptr & 3);
@@ -294,7 +294,7 @@ follow_shortcut:
} while (sc_level < shortcut->skip_to_level);
/* The shortcut matches the leaf's index to this point. */
- cursor = ACCESS_ONCE(shortcut->next_node);
+ cursor = READ_ONCE(shortcut->next_node);
if (((level ^ sc_level) & ~ASSOC_ARRAY_KEY_CHUNK_MASK) != 0) {
level = sc_level;
goto jumped;
@@ -337,7 +337,7 @@ void *assoc_array_find(const struct assoc_array *array,
* the terminal node.
*/
for (slot = 0; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
- ptr = ACCESS_ONCE(node->slots[slot]);
+ ptr = READ_ONCE(node->slots[slot]);
if (ptr && assoc_array_ptr_is_leaf(ptr)) {
/* We need a barrier between the read of the pointer
* and dereferencing the pointer - but only if we are
diff --git a/lib/dynamic_queue_limits.c b/lib/dynamic_queue_limits.c
index f346715e2255..81770a55cb16 100644
--- a/lib/dynamic_queue_limits.c
+++ b/lib/dynamic_queue_limits.c
@@ -20,7 +20,7 @@ void dql_completed(struct dql *dql, unsigned int count)
unsigned int ovlimit, completed, num_queued;
bool all_prev_completed;
- num_queued = ACCESS_ONCE(dql->num_queued);
+ num_queued = READ_ONCE(dql->num_queued);
/* Can't complete more than what's in queue */
BUG_ON(count > num_queued - dql->num_completed);
diff --git a/lib/llist.c b/lib/llist.c
index ae5872b1df0c..7062e931a7bb 100644
--- a/lib/llist.c
+++ b/lib/llist.c
@@ -41,7 +41,7 @@ bool llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,
struct llist_node *first;
do {
- new_last->next = first = ACCESS_ONCE(head->first);
+ new_last->next = first = READ_ONCE(head->first);
} while (cmpxchg(&head->first, first, new_first) != first);
return !first;
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 86c3385b9eb3..1746bae94d41 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -620,8 +620,8 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp
rcu_read_lock();
for (i = 0; i < depth; i++, d = p) {
- p = ACCESS_ONCE(d->d_parent);
- array[i] = ACCESS_ONCE(d->d_name.name);
+ p = READ_ONCE(d->d_parent);
+ array[i] = READ_ONCE(d->d_name.name);
if (p == d) {
if (i)
array[i] = "";