Op 29-05-13 12:33, Inki Dae schreef:
> Hi,
>
> Just minor comments
>
> +Usage
>> +-----
>> +
>> +Three different ways to acquire locks within the same w/w class. Common
>> +definitions for methods #1 and #2:
>> +
>> +static DEFINE_WW_CLASS(ww_class);
>> +
>> +struct obj {
>> + struct ww_mutex lock;
>> + /* obj data */
>> +};
>> +
>> +struct obj_entry {
>> + struct list_head *list;
>> + struct obj *obj;
>> +};
>> +
>> +Method 1, using a list in execbuf->buffers that's not allowed to be
>> reordered.
>> +This is useful if a list of required objects is already tracked somewhere.
>> +Furthermore the lock helper can use propagate the -EALREADY return code
>> back to
>> +the caller as a signal that an object is twice on the list. This is
>> useful if
>> +the list is constructed from userspace input and the ABI requires
>> userspace to
>> +not have duplicate entries (e.g. for a gpu commandbuffer submission
>> ioctl).
>> +
>> +int lock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
>> +{
>> + struct obj *res_obj = NULL;
>> + struct obj_entry *contended_entry = NULL;
>> + struct obj_entry *entry;
>> +
>> + ww_acquire_init(ctx, &ww_class);
>> +
>> +retry:
>> + list_for_each_entry (list, entry) {
>> + if (entry == res_obj) {
>>
Indeed, documentation was wrong. With the below diff it should almost compile now.
I really don't want to know if it really does, it's meant to be documentation!
diff --git a/Documentation/ww-mutex-design.txt b/Documentation/ww-mutex-design.txt
index 8bd1761..379739c 100644
--- a/Documentation/ww-mutex-design.txt
+++ b/Documentation/ww-mutex-design.txt
@@ -100,7 +100,7 @@ struct obj {
};
struct obj_entry {
- struct list_head *list;
+ struct list_head head;
struct obj *obj;
};
@@ -120,14 +120,14 @@ int lock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
ww_acquire_init(ctx, &ww_class);
retry:
- list_for_each_entry (list, entry) {
- if (entry == res_obj) {
+ list_for_each_entry (entry, list, head) {
+ if (entry->obj == res_obj) {
res_obj = NULL;
continue;
}
ret = ww_mutex_lock(&entry->obj->lock, ctx);
if (ret < 0) {
- contended_obj = entry;
+ contended_entry = entry;
goto err;
}
}
@@ -136,7 +136,7 @@ retry:
return 0;
err:
- list_for_each_entry_continue_reverse (list, contended_entry, entry)
+ list_for_each_entry_continue_reverse (entry, list, head)
ww_mutex_unlock(&entry->obj->lock);
if (res_obj)
@@ -163,13 +163,13 @@ int lock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
ww_acquire_init(ctx, &ww_class);
- list_for_each_entry (list, entry) {
+ list_for_each_entry (entry, list, head) {
ret = ww_mutex_lock(&entry->obj->lock, ctx);
if (ret < 0) {
entry2 = entry;
- list_for_each_entry_continue_reverse (list, entry2)
- ww_mutex_unlock(&entry->obj->lock);
+ list_for_each_entry_continue_reverse (entry2, list, head)
+ ww_mutex_unlock(&entry2->obj->lock);
if (ret != -EDEADLK) {
ww_acquire_fini(ctx);
@@ -184,8 +184,8 @@ int lock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
* buf->next to the first unlocked entry,
* restarting the for loop.
*/
- list_del(&entry->list);
- list_add(&entry->list, list);
+ list_del(&entry->head);
+ list_add(&entry->head, list);
}
}
@@ -199,7 +199,7 @@ void unlock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
{
struct obj_entry *entry;
- list_for_each_entry (list, entry)
+ list_for_each_entry (entry, list, head)
ww_mutex_unlock(&entry->obj->lock);
ww_acquire_fini(ctx);
@@ -244,22 +244,21 @@ struct obj {
static DEFINE_WW_CLASS(ww_class);
-void __unlock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
+void __unlock_objs(struct list_head *list)
{
- struct obj entry;
+ struct obj *entry, *temp;
- for_each_safe (list, entry) {
+ list_for_each_entry_safe (entry, temp, list, locked_list) {
/* need to do that before unlocking, since only the current lock holder is
allowed to use object */
- list_del(entry->locked_list);
+ list_del(&entry->locked_list);
ww_mutex_unlock(entry->ww_mutex)
}
}
void lock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
{
- struct list_head locked_buffers;
- struct obj obj = NULL, entry;
+ struct obj *obj;
ww_acquire_init(ctx, &ww_class);
@@ -275,15 +274,15 @@ retry:
continue;
}
if (ret == -EDEADLK) {
- __unlock_objs(list, ctx);
+ __unlock_objs(list);
ww_mutex_lock_slow(obj, ctx);
- list_add(locked_buffers, entry->locked_list);
+ list_add(&entry->locked_list, list);
goto retry;
}
/* locked a new object, add it to the list */
- list_add(locked_buffers, entry->locked_list);
+ list_add_tail(&entry->locked_list, list);
}
ww_acquire_done(ctx);
@@ -292,7 +291,7 @@ retry:
void unlock_objs(struct list_head *list, struct ww_acquire_ctx *ctx)
{
- __unlock_objs(list, ctx);
+ __unlock_objs(list);
ww_acquire_fini(ctx);
}
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