| Message ID | 20190221102924.13442-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/6] drm/i915: Reorder struct_mutex-vs-reset_lock in i915_gem_fault() | expand |
Chris Wilson <chris@chris-wilson.co.uk> writes: > Annoyingly, struct_mutex was not entirely eliminated from the reset > pathway; for reasons of its own, intel_display_resumes() requires > struct_mutex to prepare the planes it already captured. To avoid the > immediate problem of a deadlock between the struct_mutex and the reset > srcu, we have to acquire the reset_lock before struct_mutex in > i915_gem_fault(). Now any wait underneath struct_mutex will result us in > having to forcibly reset all inflight rendering, less than ideal. > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Mika Kuoppala <mika.kuoppala@intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> > --- > drivers/gpu/drm/i915/i915_gem.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index cc88e7974422..62e4df1cbf87 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -1834,9 +1834,15 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) > > wakeref = intel_runtime_pm_get(dev_priv); > > + srcu = i915_reset_trylock(dev_priv); > + if (srcu < 0) { > + ret = srcu; > + goto err_rpm; > + } > + > ret = i915_mutex_lock_interruptible(dev); > if (ret) > - goto err_rpm; > + goto err_reset; > > /* Access to snoopable pages through the GTT is incoherent. */ > if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev_priv)) { > @@ -1885,12 +1891,6 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) > if (ret) > goto err_unpin; > > - srcu = i915_reset_trylock(dev_priv); > - if (srcu < 0) { > - ret = srcu; > - goto err_fence; > - } > - > /* Finally, remap it using the new GTT offset */ > ret = remap_io_mapping(area, > area->vm_start + (vma->ggtt_view.partial.offset << PAGE_SHIFT), > @@ -1898,7 +1898,7 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) > min_t(u64, vma->size, area->vm_end - area->vm_start), > &ggtt->iomap); > if (ret) > - goto err_reset; > + goto err_fence; > > /* Mark as being mmapped into userspace for later revocation */ > assert_rpm_wakelock_held(dev_priv); > @@ -1908,14 +1908,14 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) > > i915_vma_set_ggtt_write(vma); > > -err_reset: > - i915_reset_unlock(dev_priv, srcu); > err_fence: > i915_vma_unpin_fence(vma); > err_unpin: > __i915_vma_unpin(vma); > err_unlock: > mutex_unlock(&dev->struct_mutex); > +err_reset: > + i915_reset_unlock(dev_priv, srcu); > err_rpm: > intel_runtime_pm_put(dev_priv, wakeref); > i915_gem_object_unpin_pages(obj); > -- > 2.20.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index cc88e7974422..62e4df1cbf87 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1834,9 +1834,15 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) wakeref = intel_runtime_pm_get(dev_priv); + srcu = i915_reset_trylock(dev_priv); + if (srcu < 0) { + ret = srcu; + goto err_rpm; + } + ret = i915_mutex_lock_interruptible(dev); if (ret) - goto err_rpm; + goto err_reset; /* Access to snoopable pages through the GTT is incoherent. */ if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev_priv)) { @@ -1885,12 +1891,6 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) if (ret) goto err_unpin; - srcu = i915_reset_trylock(dev_priv); - if (srcu < 0) { - ret = srcu; - goto err_fence; - } - /* Finally, remap it using the new GTT offset */ ret = remap_io_mapping(area, area->vm_start + (vma->ggtt_view.partial.offset << PAGE_SHIFT), @@ -1898,7 +1898,7 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) min_t(u64, vma->size, area->vm_end - area->vm_start), &ggtt->iomap); if (ret) - goto err_reset; + goto err_fence; /* Mark as being mmapped into userspace for later revocation */ assert_rpm_wakelock_held(dev_priv); @@ -1908,14 +1908,14 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) i915_vma_set_ggtt_write(vma); -err_reset: - i915_reset_unlock(dev_priv, srcu); err_fence: i915_vma_unpin_fence(vma); err_unpin: __i915_vma_unpin(vma); err_unlock: mutex_unlock(&dev->struct_mutex); +err_reset: + i915_reset_unlock(dev_priv, srcu); err_rpm: intel_runtime_pm_put(dev_priv, wakeref); i915_gem_object_unpin_pages(obj);
Annoyingly, struct_mutex was not entirely eliminated from the reset pathway; for reasons of its own, intel_display_resumes() requires struct_mutex to prepare the planes it already captured. To avoid the immediate problem of a deadlock between the struct_mutex and the reset srcu, we have to acquire the reset_lock before struct_mutex in i915_gem_fault(). Now any wait underneath struct_mutex will result us in having to forcibly reset all inflight rendering, less than ideal. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@intel.com> --- drivers/gpu/drm/i915/i915_gem.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)