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Commit 1a9d60a3 authored by Jordan Crouse's avatar Jordan Crouse Committed by Gerrit - the friendly Code Review server
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msm: kgsl: Reserve a context ID slot but don't populate immediately 



When creating a context allocate an ID but don't populate the slot
with the context pointer until we are done setup up the rest of the
process. This avoids a race if somebody tries to free the same
identifier before the create operation is complete.

Change-Id: Ic0dedbadca5b4cc4ce567afad48a33078b549439
Signed-off-by: default avatarJordan Crouse <jcrouse@codeaurora.org>
parent 5d95fbb8

drivers/gpu/msm/kgsl.c

+13 −8
Original line number Diff line number Diff line
@@ -525,21 +525,18 @@ void kgsl_context_dump(struct kgsl_context *context) 
EXPORT_SYMBOL(kgsl_context_dump);



/* Allocate a new context ID */

static int _kgsl_get_context_id(struct kgsl_device *device,

		struct kgsl_context *context)

static int _kgsl_get_context_id(struct kgsl_device *device)

{

	int id;



	idr_preload(GFP_KERNEL);

	write_lock(&device->context_lock);

	id = idr_alloc(&device->context_idr, context, 1,

	/* Allocate the slot but don't put a pointer in it yet */

	id = idr_alloc(&device->context_idr, NULL, 1,

		KGSL_MEMSTORE_MAX, GFP_NOWAIT);

	write_unlock(&device->context_lock);

	idr_preload_end();



	if (id > 0)

		context->id = id;



	return id;

}
@@ -563,7 +560,7 @@ int kgsl_context_init(struct kgsl_device_private *dev_priv, 
	char name[64];

	int ret = 0, id;



	id = _kgsl_get_context_id(device, context);

	id = _kgsl_get_context_id(device);

	if (id == -ENOSPC) {

		/*

		 * Before declaring that there are no contexts left try
@@ -572,7 +569,7 @@ int kgsl_context_init(struct kgsl_device_private *dev_priv, 
		 */



		flush_workqueue(device->events_wq);

		id = _kgsl_get_context_id(device, context);

		id = _kgsl_get_context_id(device);

	}



	if (id < 0) {
@@ -584,6 +581,8 @@ int kgsl_context_init(struct kgsl_device_private *dev_priv, 
		return id;

	}



	context->id = id;



	kref_init(&context->refcount);

	/*

	 * Get a refernce to the process private so its not destroyed, until
@@ -1713,6 +1712,12 @@ long kgsl_ioctl_drawctxt_create(struct kgsl_device_private *dev_priv, 
		goto done;

	}

	trace_kgsl_context_create(dev_priv->device, context, param->flags);



	/* Commit the pointer to the context in context_idr */

	write_lock(&device->context_lock);

	idr_replace(&device->context_idr, context, context->id);

	write_unlock(&device->context_lock);



	param->drawctxt_id = context->id;

done:

	return result;