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Commit 5eeeb523 authored by Prakash Kamliya's avatar Prakash Kamliya Committed by Gerrit - the friendly Code Review server
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msm: kgsl: Use spin_lock_bh to avoid spinlock recursion 



A sync fence timeout may lead to call adreno_drawctxt_dump()
for drawctxt sync pt dump, at the same time, its quite possible
that the cmdbatch timer expires on the *same* CPU, this will
also lead to call adreno_drawctx_dump(). This result into spin
lock recursion. Use spin_lock_bh instead of spin_lock to disable
soft irq (timer) while we are dumping the sync pt information.

Along with this change, few _irq are replaced with _bh, which
is enough to disable soft irq (timers).

Change-Id: I0d56601b81ded7c4821e2d9a837fb9e6b121ea8a
Signed-off-by: default avatarPrakash Kamliya <pkamliya@codeaurora.org>
parent 0bb9093c

drivers/gpu/msm/adreno_debugfs.c

+8 −4
Original line number Diff line number Diff line
@@ -112,10 +112,14 @@ static void print_flags(struct seq_file *s, const struct flag_entry *table, 
static void cmdbatch_print(struct seq_file *s, struct kgsl_cmdbatch *cmdbatch)

{

	struct kgsl_cmdbatch_sync_event *sync_event;

	unsigned long flags;



	/* print fences first, since they block this cmdbatch */

	spin_lock_irqsave(&cmdbatch->lock, flags);

	/*

	 * print fences first, since they block this cmdbatch.

	 * We may have cmdbatch timer running, which also uses

	 * same lock, take a lock with software interrupt disabled (bh)

	 * to avoid spin lock recursion.

	 */

	spin_lock_bh(&cmdbatch->lock);



	list_for_each_entry(sync_event, &cmdbatch->synclist, node) {

		/*
@@ -128,7 +132,7 @@ static void cmdbatch_print(struct seq_file *s, struct kgsl_cmdbatch *cmdbatch) 
		seq_puts(s, "\n");

	}



	spin_unlock_irqrestore(&cmdbatch->lock, flags);

	spin_unlock_bh(&cmdbatch->lock);



	/* if this flag is set, there won't be an IB */

	if (cmdbatch->flags & KGSL_CONTEXT_SYNC)

drivers/gpu/msm/adreno_dispatch.c

+7 −3
Original line number Diff line number Diff line
@@ -293,7 +293,6 @@ static struct kgsl_cmdbatch *_get_cmdbatch(struct adreno_context *drawctxt) 
{

	struct kgsl_cmdbatch *cmdbatch = NULL;

	bool pending = false;

	unsigned long flags;



	if (drawctxt->cmdqueue_head == drawctxt->cmdqueue_tail)

		return NULL;
@@ -323,10 +322,15 @@ static struct kgsl_cmdbatch *_get_cmdbatch(struct adreno_context *drawctxt) 
			pending = true;

	}



	spin_lock_irqsave(&cmdbatch->lock, flags);

	/*

	 * We may have cmdbatch timer running, which also uses same lock,

	 * take a lock with software interrupt disabled (bh) to avoid

	 * spin lock recursion.

	 */

	spin_lock_bh(&cmdbatch->lock);

	if (!list_empty(&cmdbatch->synclist))

		pending = true;

	spin_unlock_irqrestore(&cmdbatch->lock, flags);

	spin_unlock_bh(&cmdbatch->lock);



	/*

	 * If changes are pending and the canary timer hasn't been

drivers/gpu/msm/adreno_drawctxt.c

+7 −2
Original line number Diff line number Diff line
@@ -84,7 +84,12 @@ void adreno_drawctxt_dump(struct kgsl_device *device, 
			goto stats;

		}



		spin_lock(&cmdbatch->lock);

		/*

		 * We may have cmdbatch timer running, which also uses same

		 * lock, take a lock with software interrupt disabled (bh)

		 * to avoid spin lock recursion.

		 */

		spin_lock_bh(&cmdbatch->lock);



		if (!list_empty(&cmdbatch->synclist)) {

			dev_err(device->dev,
@@ -93,7 +98,7 @@ void adreno_drawctxt_dump(struct kgsl_device *device, 


			kgsl_dump_syncpoints(device, cmdbatch);

		}

		spin_unlock(&cmdbatch->lock);

		spin_unlock_bh(&cmdbatch->lock);

	}



stats:

drivers/gpu/msm/kgsl.c

+16 −8
Original line number Diff line number Diff line
@@ -1600,6 +1600,7 @@ static void _kgsl_cmdbatch_timer(unsigned long data) 
	if (cmdbatch == NULL || cmdbatch->context == NULL)

		return;



	/* We are in timer context, this can be non-bh */

	spin_lock(&cmdbatch->lock);

	if (list_empty(&cmdbatch->synclist))

		goto done;
@@ -1697,9 +1698,13 @@ static void kgsl_cmdbatch_sync_expire(struct kgsl_device *device, 
	struct kgsl_cmdbatch_sync_event *e, *tmp;

	int sched = 0;

	int removed = 0;

	unsigned long flags;



	spin_lock_irqsave(&event->cmdbatch->lock, flags);

	/*

	 * We may have cmdbatch timer running, which also uses same lock,

	 * take a lock with software interrupt disabled (bh) to avoid

	 * spin lock recursion.

	 */

	spin_lock_bh(&event->cmdbatch->lock);



	/*

	 * sync events that are contained by a cmdbatch which has been
@@ -1715,7 +1720,7 @@ static void kgsl_cmdbatch_sync_expire(struct kgsl_device *device, 
	}



	sched = list_empty(&event->cmdbatch->synclist) ? 1 : 0;

	spin_unlock_irqrestore(&event->cmdbatch->lock, flags);

	spin_unlock_bh(&event->cmdbatch->lock);



	/* If the list is empty delete the canary timer */

	if (sched)
@@ -1781,6 +1786,7 @@ void kgsl_cmdbatch_destroy(struct kgsl_cmdbatch *cmdbatch) 
	/* Zap the canary timer */

	del_timer_sync(&cmdbatch->timer);



	/* non-bh because we just destroyed timer */

	spin_lock(&cmdbatch->lock);



	/* Empty the synclist before canceling events */
@@ -1869,7 +1875,6 @@ static int kgsl_cmdbatch_add_sync_fence(struct kgsl_device *device, 
{

	struct kgsl_cmd_syncpoint_fence *sync = priv;

	struct kgsl_cmdbatch_sync_event *event;

	unsigned long flags;



	event = kzalloc(sizeof(*event), GFP_KERNEL);
@@ -1897,9 +1902,11 @@ static int kgsl_cmdbatch_add_sync_fence(struct kgsl_device *device, 
	 */



	kref_get(&event->refcount);

	spin_lock_irqsave(&cmdbatch->lock, flags);



	/* non-bh because, we haven't started cmdbatch timer yet */

	spin_lock(&cmdbatch->lock);

	list_add(&event->node, &cmdbatch->synclist);

	spin_unlock_irqrestore(&cmdbatch->lock, flags);

	spin_unlock(&cmdbatch->lock);



	/*

	 * Increment the reference count for the async callback.
@@ -1920,9 +1927,9 @@ static int kgsl_cmdbatch_add_sync_fence(struct kgsl_device *device, 
		kgsl_cmdbatch_sync_event_put(event);



		/* Remove event from the synclist */

		spin_lock_irqsave(&cmdbatch->lock, flags);

		spin_lock(&cmdbatch->lock);

		list_del(&event->node);

		spin_unlock_irqrestore(&cmdbatch->lock, flags);

		spin_unlock(&cmdbatch->lock);

		kgsl_cmdbatch_sync_event_put(event);



		/* Event no longer needed by this function */
@@ -2013,6 +2020,7 @@ static int kgsl_cmdbatch_add_sync_timestamp(struct kgsl_device *device, 
	kref_init(&event->refcount);

	kref_get(&event->refcount);



	/* non-bh because, we haven't started cmdbatch timer yet */

	spin_lock(&cmdbatch->lock);

	list_add(&event->node, &cmdbatch->synclist);

	spin_unlock(&cmdbatch->lock);