I have experienced a number of NULL pointer dereferences on
suspend/resume where ring->private is NULL. These come from failed
initialization of the ring buffer. Sincce this doesn't seem to be easily
recoverable, this patch adds a BUG_ON and a bread crumb pointer for
people who might encounter this in the future.
Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
drivers/gpu/drm/i915/intel_ringbuffer.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index ca3972f..8357822 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -198,9 +198,17 @@ gen6_render_ring_flush(struct intel_ring_buffer *ring,
{
u32 flags = 0;
struct pipe_control *pc = ring->private;
- u32 scratch_addr = pc->gtt_offset + 128;
+ u32 scratch_addr;
int ret;
+ /* This condition was being hit when the ring buffer wasn't being
+ * properly initialized and subsequently cleaned (hence setting
+ * ring->private to NULL).
+ */
+ BUG_ON(pc == NULL);
+
+ scratch_addr = pc->gtt_offset + 128;
+
/* Force SNB workarounds for PIPE_CONTROL flushes */
intel_emit_post_sync_nonzero_flush(ring);
--
1.7.7.3
