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drm/i915: Remove support for unlocked i915_vma unbind

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Now that we require the object lock for all ops, some code handling
race conditions can be removed.

This is required to not take short-term pins inside execbuf.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220114132320.109030-6-maarten.lankhorst@linux.intel.com
This commit is contained in:
Maarten Lankhorst 2022-01-14 14:23:19 +01:00
parent 0f341974cb
commit 294996a98a
1 changed files with 8 additions and 47 deletions
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55
drivers/gpu/drm/i915/i915_vma.c
View File

@ -838,7 +838,6 @@ i915_vma_detach(struct i915_vma *vma)
static bool try_qad_pin(struct i915_vma *vma, unsigned int flags)
{
unsigned int bound;
bool pinned = true;
bound = atomic_read(&vma->flags);
do {
@ -848,34 +847,10 @@ static bool try_qad_pin(struct i915_vma *vma, unsigned int flags)
if (unlikely(bound & (I915_VMA_OVERFLOW | I915_VMA_ERROR)))
return false;
if (!(bound & I915_VMA_PIN_MASK))
goto unpinned;
GEM_BUG_ON(((bound + 1) & I915_VMA_PIN_MASK) == 0);
} while (!atomic_try_cmpxchg(&vma->flags, &bound, bound + 1));
return true;
unpinned:
/*
* If pin_count==0, but we are bound, check under the lock to avoid
* racing with a concurrent i915_vma_unbind().
*/
mutex_lock(&vma->vm->mutex);
do {
if (unlikely(bound & (I915_VMA_OVERFLOW | I915_VMA_ERROR))) {
pinned = false;
break;
}
if (unlikely(flags & ~bound)) {
pinned = false;
break;
}
} while (!atomic_try_cmpxchg(&vma->flags, &bound, bound + 1));
mutex_unlock(&vma->vm->mutex);
return pinned;
}
static struct scatterlist *
@ -1159,7 +1134,6 @@ static int
__i915_vma_get_pages(struct i915_vma *vma)
{
struct sg_table *pages;
int ret;
/*
* The vma->pages are only valid within the lifespan of the borrowed
@ -1192,18 +1166,16 @@ __i915_vma_get_pages(struct i915_vma *vma)
break;
}
ret = 0;
if (IS_ERR(pages)) {
ret = PTR_ERR(pages);
pages = NULL;
drm_err(&vma->vm->i915->drm,
"Failed to get pages for VMA view type %u (%d)!\n",
vma->ggtt_view.type, ret);
"Failed to get pages for VMA view type %u (%ld)!\n",
vma->ggtt_view.type, PTR_ERR(pages));
return PTR_ERR(pages);
}
vma->pages = pages;
return ret;
return 0;
}
I915_SELFTEST_EXPORT int i915_vma_get_pages(struct i915_vma *vma)
@ -1235,25 +1207,14 @@ err_unpin:
static void __vma_put_pages(struct i915_vma *vma, unsigned int count)
{
/* We allocate under vma_get_pages, so beware the shrinker */
struct sg_table *pages = READ_ONCE(vma->pages);
GEM_BUG_ON(atomic_read(&vma->pages_count) < count);
if (atomic_sub_return(count, &vma->pages_count) == 0) {
/*
* The atomic_sub_return is a read barrier for the READ_ONCE of
* vma->pages above.
*
* READ_ONCE is safe because this is either called from the same
* function (i915_vma_pin_ww), or guarded by vma->vm->mutex.
*
* TODO: We're leaving vma->pages dangling, until vma->obj->resv
* lock is required.
*/
if (pages != vma->obj->mm.pages) {
sg_free_table(pages);
kfree(pages);
if (vma->pages != vma->obj->mm.pages) {
sg_free_table(vma->pages);
kfree(vma->pages);
}
vma->pages = NULL;
i915_gem_object_unpin_pages(vma->obj);
}