Re: [PATCH 15/21] drm/i915/gt: Drop i915_address_space::file

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Apr 23, 2021 at 05:31:25PM -0500, Jason Ekstrand wrote:
> There's a big comment saying how useful it is but no one is using this
> for anything.
> 
> Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>

I was trying to find anything before all your deletions, but alas nothing.
I did spent a bit of time on this, and discovered that the debugfs use was
nuked in

db80a1294c23 ("drm/i915/gem: Remove per-client stats from debugfs/i915_gem_objects")

After going through quite a few iterations, e.g.

5b5efdf79abf ("drm/i915: Make debugfs/per_file_stats scale better")
f6e8aa387171 ("drm/i915: Report the number of closed vma held by each context in debugfs")

The above removed the need for vm->file because stats debugfs file
filtered using stats->vm instead of stats->file.

History goes on until the original introduction of this (again for
debugfs) in

2bfa996e031b ("drm/i915: Store owning file on the i915_address_space")

> ---
>  drivers/gpu/drm/i915/gem/i915_gem_context.c |  9 ---------
>  drivers/gpu/drm/i915/gt/intel_gtt.h         | 10 ----------
>  drivers/gpu/drm/i915/selftests/mock_gtt.c   |  1 -
>  3 files changed, 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> index 7929d5a8be449..db9153e0f85a7 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> @@ -921,17 +921,10 @@ static int gem_context_register(struct i915_gem_context *ctx,
>  				u32 *id)
>  {
>  	struct drm_i915_private *i915 = ctx->i915;
> -	struct i915_address_space *vm;
>  	int ret;
>  
>  	ctx->file_priv = fpriv;
>  
> -	mutex_lock(&ctx->mutex);
> -	vm = i915_gem_context_vm(ctx);
> -	if (vm)
> -		WRITE_ONCE(vm->file, fpriv); /* XXX */
> -	mutex_unlock(&ctx->mutex);
> -
>  	ctx->pid = get_task_pid(current, PIDTYPE_PID);
>  	snprintf(ctx->name, sizeof(ctx->name), "%s[%d]",
>  		 current->comm, pid_nr(ctx->pid)); 
> @@ -1030,8 +1023,6 @@ int i915_gem_vm_create_ioctl(struct drm_device *dev, void *data,
>  	if (IS_ERR(ppgtt))
>  		return PTR_ERR(ppgtt);
>  
> -	ppgtt->vm.file = file_priv;
> -
>  	if (args->extensions) {
>  		err = i915_user_extensions(u64_to_user_ptr(args->extensions),
>  					   NULL, 0,
> diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
> index e67e34e179131..4c46068e63c9d 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gtt.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
> @@ -217,16 +217,6 @@ struct i915_address_space {

Pls also delete the drm_i915_file_private pre-dcl in this file.

With this added and the history adequately covered in the commit message:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>


>  	struct intel_gt *gt;
>  	struct drm_i915_private *i915;
>  	struct device *dma;
> -	/*
> -	 * Every address space belongs to a struct file - except for the global
> -	 * GTT that is owned by the driver (and so @file is set to NULL). In
> -	 * principle, no information should leak from one context to another
> -	 * (or between files/processes etc) unless explicitly shared by the
> -	 * owner. Tracking the owner is important in order to free up per-file
> -	 * objects along with the file, to aide resource tracking, and to
> -	 * assign blame.
> -	 */
> -	struct drm_i915_file_private *file;
>  	u64 total;		/* size addr space maps (ex. 2GB for ggtt) */
>  	u64 reserved;		/* size addr space reserved */
>  
> diff --git a/drivers/gpu/drm/i915/selftests/mock_gtt.c b/drivers/gpu/drm/i915/selftests/mock_gtt.c
> index 5c7ae40bba634..cc047ec594f93 100644
> --- a/drivers/gpu/drm/i915/selftests/mock_gtt.c
> +++ b/drivers/gpu/drm/i915/selftests/mock_gtt.c
> @@ -73,7 +73,6 @@ struct i915_ppgtt *mock_ppgtt(struct drm_i915_private *i915, const char *name)
>  	ppgtt->vm.gt = &i915->gt;
>  	ppgtt->vm.i915 = i915;
>  	ppgtt->vm.total = round_down(U64_MAX, PAGE_SIZE);
> -	ppgtt->vm.file = ERR_PTR(-ENODEV);
>  	ppgtt->vm.dma = i915->drm.dev;
>  
>  	i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT);
> -- 
> 2.31.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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