Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> As the fence may be signaled concurrently from an interrupt on another
> device, it is possible for the list of requests on the timeline to be
> modified as we walk it. Take both (the context's timeline and the global
> timeline) locks to prevent such modifications.
>
> Fixes: 80b204bce8f2 ("drm/i915: Enable multiple timelines")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Cc: <drm-intel-fixes@xxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 2d736442c6ab..d94df127d9f6 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2725,6 +2725,7 @@ static void i915_gem_reset_engine(struct intel_engine_cs *engine)
> struct drm_i915_gem_request *request;
> struct i915_gem_context *incomplete_ctx;
> struct intel_timeline *timeline;
> + unsigned long flags;
> bool ring_hung;
>
> if (engine->irq_seqno_barrier)
> @@ -2768,13 +2769,20 @@ static void i915_gem_reset_engine(struct intel_engine_cs *engine)
> if (i915_gem_context_is_default(incomplete_ctx))
> return;
>
> + timeline = i915_gem_context_lookup_timeline(incomplete_ctx, engine);
> +
> + spin_lock_irqsave(&engine->timeline->lock, flags);
> + spin_lock(&timeline->lock);
> +
> list_for_each_entry_continue(request, &engine->timeline->requests, link)
> if (request->ctx == incomplete_ctx)
> reset_request(request);
>
> - timeline = i915_gem_context_lookup_timeline(incomplete_ctx, engine);
> list_for_each_entry(request, &timeline->requests, link)
> reset_request(request);
> +
> + spin_unlock(&timeline->lock);
> + spin_unlock_irqrestore(&engine->timeline->lock, flags);
> }
>
> void i915_gem_reset(struct drm_i915_private *dev_priv)
> --
> 2.11.0
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