diff options
| -rw-r--r-- | drivers/gpu/drm/i915/i915_irq.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index bd56ca629b31..637c13211613 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -2784,6 +2784,26 @@ semaphore_waits_for(struct intel_engine_cs *ring, u32 *seqno) u64 offset = 0; int i, backwards; + /* + * This function does not support execlist mode - any attempt to + * proceed further into this function will result in a kernel panic + * when dereferencing ring->buffer, which is not set up in execlist + * mode. + * + * The correct way of doing it would be to derive the currently + * executing ring buffer from the current context, which is derived + * from the currently running request. Unfortunately, to get the + * current request we would have to grab the struct_mutex before doing + * anything else, which would be ill-advised since some other thread + * might have grabbed it already and managed to hang itself, causing + * the hang checker to deadlock. + * + * Therefore, this function does not support execlist mode in its + * current form. Just return NULL and move on. + */ + if (ring->buffer == NULL) + return NULL; + ipehr = I915_READ(RING_IPEHR(ring->mmio_base)); if (!ipehr_is_semaphore_wait(ring->dev, ipehr)) return NULL; |