Re: [PATCH 19/29] drm/i915: Add an i915_gem_vm_lookup helper

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, May 27, 2021 at 11:26:40AM -0500, Jason Ekstrand wrote:
> This is the VM equivalent of i915_gem_context_lookup.  It's only used
> once in this patch but future patches will need to duplicate this lookup
> code so it's better to have it in a helper.
> 
> Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>

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

> ---
>  drivers/gpu/drm/i915/gem/i915_gem_context.c |  6 +-----
>  drivers/gpu/drm/i915/i915_drv.h             | 14 ++++++++++++++
>  2 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> index d247fb223aac7..12a148ba421b6 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> @@ -1346,11 +1346,7 @@ static int set_ppgtt(struct drm_i915_file_private *file_priv,
>  	if (upper_32_bits(args->value))
>  		return -ENOENT;
>  
> -	rcu_read_lock();
> -	vm = xa_load(&file_priv->vm_xa, args->value);
> -	if (vm && !kref_get_unless_zero(&vm->ref))
> -		vm = NULL;
> -	rcu_read_unlock();
> +	vm = i915_gem_vm_lookup(file_priv, args->value);
>  	if (!vm)
>  		return -ENOENT;
>  
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 48316d273af66..fee2342219da1 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1871,6 +1871,20 @@ i915_gem_context_lookup(struct drm_i915_file_private *file_priv, u32 id)
>  	return ctx;
>  }
>  
> +static inline struct i915_address_space *
> +i915_gem_vm_lookup(struct drm_i915_file_private *file_priv, u32 id)
> +{
> +	struct i915_address_space *vm;
> +
> +	rcu_read_lock();
> +	vm = xa_load(&file_priv->vm_xa, id);
> +	if (vm && !kref_get_unless_zero(&vm->ref))
> +		vm = NULL;
> +	rcu_read_unlock();
> +
> +	return vm;
> +}
> +
>  /* i915_gem_evict.c */
>  int __must_check i915_gem_evict_something(struct i915_address_space *vm,
>  					  u64 min_size, u64 alignment,
> -- 
> 2.31.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch