On Fri, Mar 10, 2017 at 01:14:33PM +0000, Tvrtko Ursulin wrote: > > On 10/03/2017 12:21, Chris Wilson wrote: > >Provide some serialisation between user operations by waiting for the > >reset initiated by setting i915_wedged to complete. > > > >Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > >Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> > >--- > > drivers/gpu/drm/i915/i915_debugfs.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > >diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c > >index 115433d46477..a1eccf2ef313 100644 > >--- a/drivers/gpu/drm/i915/i915_debugfs.c > >+++ b/drivers/gpu/drm/i915/i915_debugfs.c > >@@ -4138,6 +4138,10 @@ i915_wedged_set(void *data, u64 val) > > i915_handle_error(dev_priv, val, > > "Manually setting wedged to %llu", val); > > > >+ wait_on_bit(&dev_priv->gpu_error.flags, > >+ I915_RESET_IN_PROGRESS, > >+ TASK_UNINTERRUPTIBLE); > >+ > > return 0; > > } > > I've spotted that the kerneldoc for wait_on_bit says "One uses > wait_on_bit() where one is waiting for the bit to clear, but has no > intention of setting it." That describes the above. > I assume this is to avoid races, which it seems this new wait also > doesn't avoid. Should it grab struct mutex across wait and > handle_error? Or if not possible what is the benefit of the patch, > just something to help IGT? Could we instead have IGT wait on the > reset in progress status itself by exporting the status? (If we > don't already, haven't looked.) The primary purpose is so that the write doesn't return until the reset it kicked (or joined) is complete. Since that is the intended side-effect of writing into i915_wedged, it made sense to me. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
