Commit 0f4308d5 authored by Thomas Hellström's avatar Thomas Hellström Committed by Matthew Auld
Browse files

drm/i915: Untangle the vma pages_mutex 



Any sleeping dma_resv lock taken while the vma pages_mutex is held
will cause a lockdep splat.
Move the i915_gem_object_pin_pages() call out of the pages_mutex
critical section.

Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210601074654.3103-2-thomas.hellstrom@linux.intel.com
parent 5b26d57f

drivers/gpu/drm/i915/i915_vma.c

+17 −12
Original line number Diff line number Diff line
@@ -800,32 +800,37 @@ static bool try_qad_pin(struct i915_vma *vma, unsigned int flags) 
static int vma_get_pages(struct i915_vma *vma)

{

	int err = 0;

	bool pinned_pages = false;



	if (atomic_add_unless(&vma->pages_count, 1, 0))

		return 0;



	/* Allocations ahoy! */

	if (mutex_lock_interruptible(&vma->pages_mutex))

		return -EINTR;



	if (!atomic_read(&vma->pages_count)) {

	if (vma->obj) {

		err = i915_gem_object_pin_pages(vma->obj);

		if (err)

				goto unlock;

			return err;

		pinned_pages = true;

	}



	/* Allocations ahoy! */

	if (mutex_lock_interruptible(&vma->pages_mutex)) {

		err = -EINTR;

		goto unpin;

	}



	if (!atomic_read(&vma->pages_count)) {

		err = vma->ops->set_pages(vma);

		if (err) {

			if (vma->obj)

				i915_gem_object_unpin_pages(vma->obj);

		if (err)

			goto unlock;

		}

		pinned_pages = false;

	}

	atomic_inc(&vma->pages_count);



unlock:

	mutex_unlock(&vma->pages_mutex);

unpin:

	if (pinned_pages)

		__i915_gem_object_unpin_pages(vma->obj);



	return err;

}