diff options
Diffstat (limited to 'drivers/gpu/drm/i915/i915_request.c')
-rw-r--r-- | drivers/gpu/drm/i915/i915_request.c | 57 |
1 files changed, 35 insertions, 22 deletions
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 73d5195146b0..62fad16a55e8 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -60,7 +60,7 @@ static struct kmem_cache *slab_execute_cbs; static const char *i915_fence_get_driver_name(struct dma_fence *fence) { - return dev_name(to_request(fence)->engine->i915->drm.dev); + return dev_name(to_request(fence)->i915->drm.dev); } static const char *i915_fence_get_timeline_name(struct dma_fence *fence) @@ -134,17 +134,42 @@ static void i915_fence_release(struct dma_fence *fence) i915_sw_fence_fini(&rq->semaphore); /* - * Keep one request on each engine for reserved use under mempressure, + * Keep one request on each engine for reserved use under mempressure * do not use with virtual engines as this really is only needed for * kernel contexts. + * + * We do not hold a reference to the engine here and so have to be + * very careful in what rq->engine we poke. The virtual engine is + * referenced via the rq->context and we released that ref during + * i915_request_retire(), ergo we must not dereference a virtual + * engine here. Not that we would want to, as the only consumer of + * the reserved engine->request_pool is the power management parking, + * which must-not-fail, and that is only run on the physical engines. + * + * Since the request must have been executed to be have completed, + * we know that it will have been processed by the HW and will + * not be unsubmitted again, so rq->engine and rq->execution_mask + * at this point is stable. rq->execution_mask will be a single + * bit if the last and _only_ engine it could execution on was a + * physical engine, if it's multiple bits then it started on and + * could still be on a virtual engine. Thus if the mask is not a + * power-of-two we assume that rq->engine may still be a virtual + * engine and so a dangling invalid pointer that we cannot dereference + * + * For example, consider the flow of a bonded request through a virtual + * engine. The request is created with a wide engine mask (all engines + * that we might execute on). On processing the bond, the request mask + * is reduced to one or more engines. If the request is subsequently + * bound to a single engine, it will then be constrained to only + * execute on that engine and never returned to the virtual engine + * after timeslicing away, see __unwind_incomplete_requests(). Thus we + * know that if the rq->execution_mask is a single bit, rq->engine + * can be a physical engine with the exact corresponding mask. */ if (!intel_engine_is_virtual(rq->engine) && - !cmpxchg(&rq->engine->request_pool, NULL, rq)) { - intel_context_put(rq->context); + is_power_of_2(rq->execution_mask) && + !cmpxchg(&rq->engine->request_pool, NULL, rq)) return; - } - - intel_context_put(rq->context); kmem_cache_free(slab_requests, rq); } @@ -611,7 +636,7 @@ bool __i915_request_submit(struct i915_request *request) goto active; } - if (unlikely(intel_context_is_banned(request->context))) + if (unlikely(!intel_context_is_schedulable(request->context))) i915_request_set_error_once(request, -EIO); if (unlikely(fatal_error(request->fence.error))) @@ -921,22 +946,11 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp) } } - /* - * Hold a reference to the intel_context over life of an i915_request. - * Without this an i915_request can exist after the context has been - * destroyed (e.g. request retired, context closed, but user space holds - * a reference to the request from an out fence). In the case of GuC - * submission + virtual engine, the engine that the request references - * is also destroyed which can trigger bad pointer dref in fence ops - * (e.g. i915_fence_get_driver_name). We could likely change these - * functions to avoid touching the engine but let's just be safe and - * hold the intel_context reference. In execlist mode the request always - * eventually points to a physical engine so this isn't an issue. - */ - rq->context = intel_context_get(ce); + rq->context = ce; rq->engine = ce->engine; rq->ring = ce->ring; rq->execution_mask = ce->engine->mask; + rq->i915 = ce->engine->i915; ret = intel_timeline_get_seqno(tl, rq, &seqno); if (ret) @@ -1008,7 +1022,6 @@ err_unwind: GEM_BUG_ON(!list_empty(&rq->sched.waiters_list)); err_free: - intel_context_put(ce); kmem_cache_free(slab_requests, rq); err_unreserve: intel_context_unpin(ce); |