[PATCH] drm/i915: Prevent timeline updates whilst performing reset

[PATCH] drm/i915: Prevent timeline updates whilst performing reset

[Chris Wilson]

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@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org>
---
 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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✓ Fi.CI.BAT: success for drm/i915: Prevent timeline updates whilst performing reset

[Patchwork]

== Series Details ==

Series: drm/i915: Prevent timeline updates whilst performing reset
URL   : https://patchwork.freedesktop.org/series/16998/
State : success

== Summary ==

Series 16998v1 drm/i915: Prevent timeline updates whilst performing reset
https://patchwork.freedesktop.org/api/1.0/series/16998/revisions/1/mbox/


fi-bdw-5557u     total:247  pass:233  dwarn:0   dfail:0   fail:0   skip:14 
fi-bsw-n3050     total:247  pass:208  dwarn:0   dfail:0   fail:0   skip:39 
fi-bxt-j4205     total:247  pass:225  dwarn:1   dfail:0   fail:0   skip:21 
fi-bxt-t5700     total:247  pass:220  dwarn:0   dfail:0   fail:0   skip:27 
fi-byt-j1900     total:247  pass:220  dwarn:0   dfail:0   fail:0   skip:27 
fi-byt-n2820     total:247  pass:216  dwarn:0   dfail:0   fail:0   skip:31 
fi-hsw-4770      total:247  pass:228  dwarn:0   dfail:0   fail:0   skip:19 
fi-hsw-4770r     total:247  pass:228  dwarn:0   dfail:0   fail:0   skip:19 
fi-ilk-650       total:247  pass:195  dwarn:0   dfail:0   fail:0   skip:52 
fi-ivb-3520m     total:247  pass:226  dwarn:0   dfail:0   fail:0   skip:21 
fi-ivb-3770      total:247  pass:226  dwarn:0   dfail:0   fail:0   skip:21 
fi-kbl-7500u     total:247  pass:226  dwarn:0   dfail:0   fail:0   skip:21 
fi-skl-6260u     total:247  pass:234  dwarn:0   dfail:0   fail:0   skip:13 
fi-skl-6700hq    total:247  pass:227  dwarn:0   dfail:0   fail:0   skip:20 
fi-skl-6700k     total:247  pass:224  dwarn:3   dfail:0   fail:0   skip:20 
fi-skl-6770hq    total:247  pass:234  dwarn:0   dfail:0   fail:0   skip:13 
fi-snb-2520m     total:247  pass:216  dwarn:0   dfail:0   fail:0   skip:31 
fi-snb-2600      total:247  pass:215  dwarn:0   dfail:0   fail:0   skip:32 

cda2d70a4395323bcf064c81ee0f89d2de015544 drm-tip: 2016y-12m-19d-13h-00m-10s UTC integration manifest
c075aaa drm/i915: Prevent timeline updates whilst performing reset

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_3330/
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Re: [PATCH] drm/i915: Prevent timeline updates whilst performing reset

[Mika Kuoppala]

Chris Wilson <chris@chris-wilson.co.uk> 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@chris-wilson.co.uk>

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>

> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Cc: <drm-intel-fixes@lists.freedesktop.org>
> ---
>  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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