| Message ID | 20210830121006.2978297-16-maarten.lankhorst@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915: Short-term pinning and async eviction. | expand |
On Mon, Aug 30, 2021 at 02:10:02PM +0200, Maarten Lankhorst wrote: >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. > Ok I get it, as i915_vma_unbind() is now called uner obj lock we don't need these race handling. But would like someone else also take a look. Acked-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com> >Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> >--- > drivers/gpu/drm/i915/i915_vma.c | 40 +++++---------------------------- > 1 file changed, 5 insertions(+), 35 deletions(-) > >diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c >index da54e6882650..f6dacfc3e840 100644 >--- a/drivers/gpu/drm/i915/i915_vma.c >+++ b/drivers/gpu/drm/i915/i915_vma.c >@@ -748,7 +748,6 @@ 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 { >@@ -758,34 +757,10 @@ 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; > } > > >@@ -1085,13 +1060,7 @@ __i915_vma_get_pages(struct i915_vma *vma) > vma->ggtt_view.type, ret); > } > >- pages = xchg(&vma->pages, pages); >- >- /* did we race against a put_pages? */ >- if (pages && pages != vma->obj->mm.pages) { >- sg_free_table(vma->pages); >- kfree(vma->pages); >- } >+ vma->pages = pages; > > return ret; > } >@@ -1125,13 +1094,14 @@ I915_SELFTEST_EXPORT int i915_vma_get_pages(struct i915_vma *vma) > 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); >+ struct sg_table *pages = vma->pages; > > GEM_BUG_ON(atomic_read(&vma->pages_count) < count); > > if (atomic_sub_return(count, &vma->pages_count) == 0) { >- if (pages == cmpxchg(&vma->pages, pages, NULL) && >- pages != vma->obj->mm.pages) { >+ vma->pages = NULL; >+ >+ if (pages != vma->obj->mm.pages) { > sg_free_table(pages); > kfree(pages); > } >-- >2.32.0 >
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index da54e6882650..f6dacfc3e840 100644 --- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -748,7 +748,6 @@ 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 { @@ -758,34 +757,10 @@ 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; } @@ -1085,13 +1060,7 @@ __i915_vma_get_pages(struct i915_vma *vma) vma->ggtt_view.type, ret); } - pages = xchg(&vma->pages, pages); - - /* did we race against a put_pages? */ - if (pages && pages != vma->obj->mm.pages) { - sg_free_table(vma->pages); - kfree(vma->pages); - } + vma->pages = pages; return ret; } @@ -1125,13 +1094,14 @@ I915_SELFTEST_EXPORT int i915_vma_get_pages(struct i915_vma *vma) 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); + struct sg_table *pages = vma->pages; GEM_BUG_ON(atomic_read(&vma->pages_count) < count); if (atomic_sub_return(count, &vma->pages_count) == 0) { - if (pages == cmpxchg(&vma->pages, pages, NULL) && - pages != vma->obj->mm.pages) { + vma->pages = NULL; + + if (pages != vma->obj->mm.pages) { sg_free_table(pages); kfree(pages); }
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> --- drivers/gpu/drm/i915/i915_vma.c | 40 +++++---------------------------- 1 file changed, 5 insertions(+), 35 deletions(-)