Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit da176acc authored by Jordan Crouse's avatar Jordan Crouse Committed by Jeremy Gebben
Browse files

msm: kgsl: Don't WARN in _kgsl_context_get 



There is a sizable window between the reference count on a context
going to zero and it actually getting removed from the idr. In the
meantime somebody else could try to get the context and fail
kref_get_unless zero(). Thats okay - it just means that you can't
trust the pointer.  This mostly comes into play with kgsl_release()
which races with all the other things that hold a context reference.

Remove the WARN and trust that all callers of _kgl_context_get()
do the right thing (as of today, they do).

Change-Id: Ic0dedbadbd9f257042da9ea7e18e7ba4f27c1a0a
Signed-off-by: default avatarJordan Crouse <jcrouse@codeaurora.org>
parent f2a01c49

drivers/gpu/msm/kgsl_cmdbatch.c

+1 −1
Original line number Diff line number Diff line
@@ -733,7 +733,7 @@ struct kgsl_cmdbatch *kgsl_cmdbatch_create(struct kgsl_device *device, 


	if (!_kgsl_context_get(context)) {

		kfree(cmdbatch);

		return ERR_PTR(-EINVAL);

		return ERR_PTR(-ENOENT);

	}



	kref_init(&cmdbatch->refcount);

drivers/gpu/msm/kgsl_device.h

+1 −9
Original line number Diff line number Diff line
@@ -724,16 +724,8 @@ static inline int _kgsl_context_get(struct kgsl_context *context) 
{

	int ret = 0;



	if (context) {

	if (context)

		ret = kref_get_unless_zero(&context->refcount);

		/*

		 * We shouldn't realistically fail kref_get_unless_zero unless

		 * we did something really dumb so make the failure both public

		 * and painful

		 */



		WARN_ON(!ret);

	}



	return ret;

}

drivers/gpu/msm/kgsl_events.c

+11 −3
Original line number Diff line number Diff line 
/* Copyright (c) 2011-2014, The Linux Foundation. All rights reserved.

/* Copyright (c) 2011-2015, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and
@@ -68,7 +68,12 @@ static void _process_event_group(struct kgsl_device *device, 


	context = group->context;



	_kgsl_context_get(context);

	/*

	 * Sanity check to be sure that we we aren't racing with the context

	 * getting destroyed

	 */

	if (context != NULL && !_kgsl_context_get(context))

		BUG();



	spin_lock(&group->lock);
@@ -251,7 +256,10 @@ int kgsl_add_event(struct kgsl_device *device, struct kgsl_event_group *group, 
		return -ENOMEM;



	/* Get a reference to the context while the event is active */

	_kgsl_context_get(context);

	if (context != NULL && !_kgsl_context_get(context)) {

		kmem_cache_free(events_cache, event);

		return -ENOENT;

	}



	event->device = device;

	event->context = context;

drivers/gpu/msm/kgsl_sync.c

+4 −2
Original line number Diff line number Diff line
@@ -115,8 +115,10 @@ static int _add_fence_event(struct kgsl_device *device, 
	 * Increase the refcount for the context to keep it through the

	 * callback

	 */



	_kgsl_context_get(context);

	if (!_kgsl_context_get(context)) {

		kfree(event);

		return -ENOENT;

	}



	event->context = context;

	event->timestamp = timestamp;