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Commit d3862e44 authored by Chris Wilson's avatar Chris Wilson Committed by Gustavo Padovan
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dma-buf/sw-sync: Fix locking around sync_timeline lists 



The sync_pt were not adding themselves atomically to the timeline lists,
corruption imminent.  Only a single list is required to track the
unsignaled sync_pt, so reduce it and rename the lock more appropriately
along with using idiomatic names to distinguish a list from links along
it.

v2: Prevent spinlock recursion on free during create (next patch) and
fixup crossref in kerneldoc

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Reviewed-by: default avatarSean Paul <seanpaul@chromium.org>
Signed-off-by: default avatarGustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170629210532.5617-1-chris@chris-wilson.co.uk
parent 3b52ce44

drivers/dma-buf/sw_sync.c

+19 −29
Original line number Diff line number Diff line
@@ -96,9 +96,8 @@ static struct sync_timeline *sync_timeline_create(const char *name) 
	obj->context = dma_fence_context_alloc(1);

	strlcpy(obj->name, name, sizeof(obj->name));



	INIT_LIST_HEAD(&obj->child_list_head);

	INIT_LIST_HEAD(&obj->active_list_head);

	spin_lock_init(&obj->child_list_lock);

	INIT_LIST_HEAD(&obj->pt_list);

	spin_lock_init(&obj->lock);



	sync_timeline_debug_add(obj);
@@ -139,17 +138,15 @@ static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc) 


	trace_sync_timeline(obj);



	spin_lock_irq(&obj->child_list_lock);

	spin_lock_irq(&obj->lock);



	obj->value += inc;



	list_for_each_entry_safe(pt, next, &obj->active_list_head,

				 active_list) {

	list_for_each_entry_safe(pt, next, &obj->pt_list, link)

		if (dma_fence_is_signaled_locked(&pt->base))

			list_del_init(&pt->active_list);

	}

			list_del_init(&pt->link);



	spin_unlock_irq(&obj->child_list_lock);

	spin_unlock_irq(&obj->lock);

}



/**
@@ -171,15 +168,15 @@ static struct sync_pt *sync_pt_create(struct sync_timeline *obj, 
	if (!pt)

		return NULL;



	spin_lock_irq(&obj->child_list_lock);



	sync_timeline_get(obj);

	dma_fence_init(&pt->base, &timeline_fence_ops, &obj->child_list_lock,

	dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock,

		       obj->context, value);

	list_add_tail(&pt->child_list, &obj->child_list_head);

	INIT_LIST_HEAD(&pt->active_list);

	INIT_LIST_HEAD(&pt->link);



	spin_unlock_irq(&obj->child_list_lock);

	spin_lock_irq(&obj->lock);

	if (!dma_fence_is_signaled_locked(&pt->base))

		list_add_tail(&pt->link, &obj->pt_list);

	spin_unlock_irq(&obj->lock);



	return pt;

}
@@ -200,15 +197,15 @@ static void timeline_fence_release(struct dma_fence *fence) 
{

	struct sync_pt *pt = dma_fence_to_sync_pt(fence);

	struct sync_timeline *parent = dma_fence_parent(fence);



	if (!list_empty(&pt->link)) {

		unsigned long flags;



		spin_lock_irqsave(fence->lock, flags);



	list_del(&pt->child_list);

	if (!list_empty(&pt->active_list))

		list_del(&pt->active_list);



		if (!list_empty(&pt->link))

			list_del(&pt->link);

		spin_unlock_irqrestore(fence->lock, flags);

	}



	sync_timeline_put(parent);

	dma_fence_free(fence);
@@ -223,13 +220,6 @@ static bool timeline_fence_signaled(struct dma_fence *fence) 


static bool timeline_fence_enable_signaling(struct dma_fence *fence)

{

	struct sync_pt *pt = dma_fence_to_sync_pt(fence);

	struct sync_timeline *parent = dma_fence_parent(fence);



	if (timeline_fence_signaled(fence))

		return false;



	list_add_tail(&pt->active_list, &parent->active_list_head);

	return true;

}

drivers/dma-buf/sync_debug.c

+4 −5
Original line number Diff line number Diff line
@@ -119,13 +119,12 @@ static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj) 


	seq_printf(s, "%s: %d\n", obj->name, obj->value);



	spin_lock_irq(&obj->child_list_lock);

	list_for_each(pos, &obj->child_list_head) {

		struct sync_pt *pt =

			container_of(pos, struct sync_pt, child_list);

	spin_lock_irq(&obj->lock);

	list_for_each(pos, &obj->pt_list) {

		struct sync_pt *pt = container_of(pos, struct sync_pt, link);

		sync_print_fence(s, &pt->base, false);

	}

	spin_unlock_irq(&obj->child_list_lock);

	spin_unlock_irq(&obj->lock);

}



static void sync_print_sync_file(struct seq_file *s,

drivers/dma-buf/sync_debug.h

+8 −13
Original line number Diff line number Diff line
@@ -24,42 +24,37 @@ 
 * struct sync_timeline - sync object

 * @kref:		reference count on fence.

 * @name:		name of the sync_timeline. Useful for debugging

 * @child_list_head:	list of children sync_pts for this sync_timeline

 * @child_list_lock:	lock protecting @child_list_head and fence.status

 * @active_list_head:	list of active (unsignaled/errored) sync_pts

 * @lock:		lock protecting @pt_list and @value

 * @pt_list:		list of active (unsignaled/errored) sync_pts

 * @sync_timeline_list:	membership in global sync_timeline_list

 */

struct sync_timeline {

	struct kref		kref;

	char			name[32];



	/* protected by child_list_lock */

	/* protected by lock */

	u64			context;

	int			value;



	struct list_head	child_list_head;

	spinlock_t		child_list_lock;



	struct list_head	active_list_head;

	struct list_head	pt_list;

	spinlock_t		lock;



	struct list_head	sync_timeline_list;

};



static inline struct sync_timeline *dma_fence_parent(struct dma_fence *fence)

{

	return container_of(fence->lock, struct sync_timeline, child_list_lock);

	return container_of(fence->lock, struct sync_timeline, lock);

}



/**

 * struct sync_pt - sync_pt object

 * @base: base fence object

 * @child_list: sync timeline child's list

 * @active_list: sync timeline active child's list

 * @link: link on the sync timeline's list

 */

struct sync_pt {

	struct dma_fence base;

	struct list_head child_list;

	struct list_head active_list;

	struct list_head link;

};



#ifdef CONFIG_SW_SYNC