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

Matthew Auld
2021-10-21T17:40:33Z

On Thu, 21 Oct 2021 at 11:37, Maarten Lankhorst
<maarten.lankhorst@linux.intel.com> wrote:
>
> i915_vma_wait_for_bind needs the vma lock held, fix the caller.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@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
>