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Commit 7dc40713 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Introduce a mutex for file_priv->context_idr 



Define a mutex for the exclusive use of interacting with the per-file
context-idr, that was previously guarded by struct_mutex. This allows us
to reduce the coverage of struct_mutex, with a view to removing the last
bits coordinating GEM context later. (In the short term, we avoid taking
struct_mutex while using the extended constructor functions, preventing
some nasty recursion.)

v2: s/context_lock/context_idr_lock/

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190321140711.11190-2-chris@chris-wilson.co.uk
parent 3aa9945a

drivers/gpu/drm/i915/i915_drv.h

+2 −0
Original line number Diff line number Diff line
@@ -216,7 +216,9 @@ struct drm_i915_file_private { 
 */

#define DRM_I915_THROTTLE_JIFFIES msecs_to_jiffies(20)

	} mm;



	struct idr context_idr;

	struct mutex context_idr_lock; /* guards context_idr */



	unsigned int bsd_engine;

drivers/gpu/drm/i915/i915_gem_context.c

+21 −26
Original line number Diff line number Diff line
@@ -579,9 +579,7 @@ void i915_gem_contexts_fini(struct drm_i915_private *i915) 


static int context_idr_cleanup(int id, void *p, void *data)

{

	struct i915_gem_context *ctx = p;



	context_close(ctx);

	context_close(p);

	return 0;

}
@@ -603,13 +601,15 @@ static int gem_context_register(struct i915_gem_context *ctx, 
	}



	/* And finally expose ourselves to userspace via the idr */

	mutex_lock(&fpriv->context_idr_lock);

	ret = idr_alloc(&fpriv->context_idr, ctx,

			DEFAULT_CONTEXT_HANDLE, 0, GFP_KERNEL);

	if (ret >= 0)

		ctx->user_handle = ret;

	mutex_unlock(&fpriv->context_idr_lock);

	if (ret < 0)

		goto err_name;



	ctx->user_handle = ret;



	return 0;



err_name:
@@ -627,10 +627,11 @@ int i915_gem_context_open(struct drm_i915_private *i915, 
	int err;



	idr_init(&file_priv->context_idr);

	mutex_init(&file_priv->context_idr_lock);



	mutex_lock(&i915->drm.struct_mutex);



	ctx = i915_gem_create_context(i915);

	mutex_unlock(&i915->drm.struct_mutex);

	if (IS_ERR(ctx)) {

		err = PTR_ERR(ctx);

		goto err;
@@ -643,14 +644,14 @@ int i915_gem_context_open(struct drm_i915_private *i915, 
	GEM_BUG_ON(ctx->user_handle != DEFAULT_CONTEXT_HANDLE);

	GEM_BUG_ON(i915_gem_context_is_kernel(ctx));



	mutex_unlock(&i915->drm.struct_mutex);



	return 0;



err_ctx:

	mutex_lock(&i915->drm.struct_mutex);

	context_close(ctx);

err:

	mutex_unlock(&i915->drm.struct_mutex);

err:

	mutex_destroy(&file_priv->context_idr_lock);

	idr_destroy(&file_priv->context_idr);

	return PTR_ERR(ctx);

}
@@ -663,6 +664,7 @@ void i915_gem_context_close(struct drm_file *file) 


	idr_for_each(&file_priv->context_idr, context_idr_cleanup, NULL);

	idr_destroy(&file_priv->context_idr);

	mutex_destroy(&file_priv->context_idr_lock);

}



static struct i915_request *
@@ -845,25 +847,22 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data, 
		return ret;



	ctx = i915_gem_create_context(i915);

	if (IS_ERR(ctx)) {

		ret = PTR_ERR(ctx);

		goto err_unlock;

	}

	mutex_unlock(&dev->struct_mutex);

	if (IS_ERR(ctx))

		return PTR_ERR(ctx);



	ret = gem_context_register(ctx, file_priv);

	if (ret)

		goto err_ctx;



	mutex_unlock(&dev->struct_mutex);



	args->ctx_id = ctx->user_handle;

	DRM_DEBUG("HW context %d created\n", args->ctx_id);



	return 0;



err_ctx:

	mutex_lock(&dev->struct_mutex);

	context_close(ctx);

err_unlock:

	mutex_unlock(&dev->struct_mutex);

	return ret;

}
@@ -874,7 +873,6 @@ int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data, 
	struct drm_i915_gem_context_destroy *args = data;

	struct drm_i915_file_private *file_priv = file->driver_priv;

	struct i915_gem_context *ctx;

	int ret;



	if (args->pad != 0)

		return -EINVAL;
@@ -882,21 +880,18 @@ int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data, 
	if (args->ctx_id == DEFAULT_CONTEXT_HANDLE)

		return -ENOENT;



	ctx = i915_gem_context_lookup(file_priv, args->ctx_id);

	if (mutex_lock_interruptible(&file_priv->context_idr_lock))

		return -EINTR;



	ctx = idr_remove(&file_priv->context_idr, args->ctx_id);

	mutex_unlock(&file_priv->context_idr_lock);

	if (!ctx)

		return -ENOENT;



	ret = mutex_lock_interruptible(&dev->struct_mutex);

	if (ret)

		goto out;



	idr_remove(&file_priv->context_idr, ctx->user_handle);

	mutex_lock(&dev->struct_mutex);

	context_close(ctx);



	mutex_unlock(&dev->struct_mutex);



out:

	i915_gem_context_put(ctx);

	return 0;

}