From 8eb4704b124cbd44f189709959137d77063ecfa1 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Sun, 3 Nov 2019 16:23:05 +0000
Subject: drm/i915: Protect request peeking with RCU
Git-commit: 8eb4704b124cbd44f189709959137d77063ecfa1
Patch-mainline: v5.5-rc1
References: bsc#1152489
Since the execlists_active() is no longer protected by the
engine->active.lock, we need to protect the request pointer with RCU to
prevent it being freed as we evaluate whether or not we need to preempt.
Fixes: df403069029d ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock")
Fixes: 13ed13a4dcbf ("drm/i915: Don't set queue_priority_hint if we don't kick the submission")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191104090158.2959-2-chris@chris-wilson.co.uk
(cherry picked from commit 7d148635253328dda7cfe55d57e3c828e9564427)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/i915/i915_scheduler.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index d2edb527dcb8..010d67f48ad9 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -202,21 +202,26 @@ static void kick_submission(struct intel_engine_cs *engine,
if (prio <= engine->execlists.queue_priority_hint)
return;
+ rcu_read_lock();
+
/* Nothing currently active? We're overdue for a submission! */
inflight = execlists_active(&engine->execlists);
if (!inflight)
- return;
+ goto unlock;
/*
* If we are already the currently executing context, don't
* bother evaluating if we should preempt ourselves.
*/
if (inflight->hw_context == rq->hw_context)
- return;
+ goto unlock;
engine->execlists.queue_priority_hint = prio;
if (need_preempt(prio, rq_prio(inflight)))
tasklet_hi_schedule(&engine->execlists.tasklet);
+
+unlock:
+ rcu_read_unlock();
}
static void __i915_schedule(struct i915_sched_node *node,
--
2.28.0