From a2487174af332f46456048f96ddd2a8c28a3839e Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 24 Oct 2017 12:55:01 +0100
Subject: [PATCH] drm/i915/execlists: Remove the priority "optimisation"
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Git-commit: a2487174af332f46456048f96ddd2a8c28a3839e
Patch-mainline: v4.15-rc1
References: FATE#322643 bsc#1055900
No-fix: 64b80085dd3603d401fc05879f700b86a3a5c8e8
Originally we set the priority to max upon inserting the request into
the execlists queue (and removing it from the scheduler lists). We could
then use the prio==INT_MAX as a shortcut within execlists_schedule() to
detect the end of the dependency chain. Since commit 1f181225f8ec
("drm/i915/execlists: Keep request->priority for its lifetime") this is
no longer true as we use the request completion as an indicator the
schedule dependency chain is complete instead. (This allows us to then
reschedule requests even when its context is in flight.) However, this
makes the GEM_BUG_ON() inside execlists_schedule() racy as we may change
the rq->prio at the same time. As the assertion is useful, let's keep
the assertion and remove the micro-optimisation.
Fixes: 1f181225f8ec ("drm/i915/execlists: Keep request->priority for its lifetime")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171024115501.21033-1-chris@chris-wilson.co.uk
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
(cherry picked from commit 64b80085dd3603d401fc05879f700b86a3a5c8e8)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/i915/intel_lrc.c | 2 --
1 file changed, 2 deletions(-)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -734,7 +734,6 @@ static void execlists_cancel_requests(st
list_for_each_entry_safe(rq, rn, &p->requests, priotree.link) {
INIT_LIST_HEAD(&rq->priotree.link);
- rq->priotree.priority = INT_MAX;
dma_fence_set_error(&rq->fence, -EIO);
__i915_gem_request_submit(rq);
@@ -891,7 +890,6 @@ static void intel_lrc_irq_handler(unsign
execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT);
trace_i915_gem_request_out(rq);
- rq->priotree.priority = INT_MAX;
i915_gem_request_put(rq);
execlists_port_complete(execlists, port);