[Intel-gfx] [PATCH 14/28] drm/i915: Take object lock in i915_ggtt_pin if ww is not set

[Matthew Auld]

On Thu, 21 Oct 2021 at 11:37, Maarten Lankhorst
<maarten.lankhorst at linux.intel.com> wrote:
>
> i915_vma_wait_for_bind needs the vma lock held, fix the caller.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_vma.c | 40 +++++++++++++++++++++++----------
>  1 file changed, 28 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index bacc8d68e495..2877dcd62acb 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -1348,23 +1348,15 @@ static void flush_idle_contexts(struct intel_gt *gt)
>         intel_gt_wait_for_idle(gt, MAX_SCHEDULE_TIMEOUT);
>  }
>
> -int i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> -                 u32 align, unsigned int flags)
> +static int __i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> +                          u32 align, unsigned int flags)
>  {
>         struct i915_address_space *vm = vma->vm;
>         int err;
>
> -       GEM_BUG_ON(!i915_vma_is_ggtt(vma));
> -
> -#ifdef CONFIG_LOCKDEP
> -       WARN_ON(!ww && dma_resv_held(vma->obj->base.resv));
> -#endif
> -
>         do {
> -               if (ww)
> -                       err = i915_vma_pin_ww(vma, ww, 0, align, flags | PIN_GLOBAL);
> -               else
> -                       err = i915_vma_pin(vma, 0, align, flags | PIN_GLOBAL);
> +               err = i915_vma_pin_ww(vma, ww, 0, align, flags | PIN_GLOBAL);
> +
>                 if (err != -ENOSPC) {
>                         if (!err) {
>                                 err = i915_vma_wait_for_bind(vma);
> @@ -1383,6 +1375,30 @@ int i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
>         } while (1);
>  }
>
> +int i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
> +                 u32 align, unsigned int flags)
> +{
> +       struct i915_gem_ww_ctx _ww;
> +       int err;
> +
> +       GEM_BUG_ON(!i915_vma_is_ggtt(vma));
> +
> +       if (ww)
> +               return __i915_ggtt_pin(vma, ww, align, flags);
> +
> +#ifdef CONFIG_LOCKDEP
> +       WARN_ON(dma_resv_held(vma->obj->base.resv));

Hmm, so this can't trigger, say if shrinker grabs the lock, or some
other concurrent user?

> +#endif
> +
> +       for_i915_gem_ww(&_ww, err, true) {
> +               err = i915_gem_object_lock(vma->obj, &_ww);
> +               if (!err)
> +                       err = __i915_ggtt_pin(vma, &_ww, align, flags);
> +       }
> +
> +       return err;
> +}
> +
>  static void __vma_close(struct i915_vma *vma, struct intel_gt *gt)
>  {
>         /*
> --
> 2.33.0
>