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); }