diff mbox series

[21/27] drm/i915/guc: Proper xarray usage for contexts_lookup

Message ID 20210819061639.21051-22-matthew.brost@intel.com (mailing list archive)
State New, archived
Headers show
Series Clean up GuC CI failures, simplify locking, and kernel DOC | expand

Commit Message

Matthew Brost Aug. 19, 2021, 6:16 a.m. UTC
Lock the xarray and take ref to the context if needed.

v2:
 (Checkpatch)
  - Add new line after declaration
 (Daniel Vetter)
  - Correct put / get accounting in xa_for_loops

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 103 +++++++++++++++---
 1 file changed, 88 insertions(+), 15 deletions(-)

Comments

Matthew Brost Aug. 26, 2021, 12:41 a.m. UTC | #1
On Wed, Aug 25, 2021 at 05:44:11PM -0700, Daniele Ceraolo Spurio wrote:
> 
> 
> On 8/18/2021 11:16 PM, Matthew Brost wrote:
> > Lock the xarray and take ref to the context if needed.
> > 
> > v2:
> >   (Checkpatch)
> >    - Add new line after declaration
> >   (Daniel Vetter)
> >    - Correct put / get accounting in xa_for_loops
> > 
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> >   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 103 +++++++++++++++---
> >   1 file changed, 88 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > index 509b298e7cf3..5f77f25322ca 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -606,8 +606,18 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> >   	unsigned long index, flags;
> >   	bool pending_disable, pending_enable, deregister, destroyed, banned;
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> >   	xa_for_each(&guc->context_lookup, index, ce) {
> > -		spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +		/*
> > +		 * Corner case where the ref count on the object is zero but and
> > +		 * deregister G2H was lost. In this case we don't touch the ref
> > +		 * count and finish the destroy of the context.
> > +		 */
> > +		bool do_put = kref_get_unless_zero(&ce->ref);
> > +
> > +		xa_unlock(&guc->context_lookup);
> > +
> > +		spin_lock(&ce->guc_state.lock);
> >   		/*
> >   		 * Once we are at this point submission_disabled() is guaranteed
> > @@ -623,7 +633,9 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> >   		banned = context_banned(ce);
> >   		init_sched_state(ce);
> > -		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +		spin_unlock(&ce->guc_state.lock);
> > +
> > +		GEM_BUG_ON(!do_put && !destroyed);
> >   		if (pending_enable || destroyed || deregister) {
> >   			decr_outstanding_submission_g2h(guc);
> > @@ -646,13 +658,19 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
> >   			}
> >   			intel_context_sched_disable_unpin(ce);
> >   			decr_outstanding_submission_g2h(guc);
> > -			spin_lock_irqsave(&ce->guc_state.lock, flags);
> > +
> > +			spin_lock(&ce->guc_state.lock);
> >   			guc_blocked_fence_complete(ce);
> > -			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > +			spin_unlock(&ce->guc_state.lock);
> >   			intel_context_put(ce);
> >   		}
> > +
> > +		if (do_put)
> > +			intel_context_put(ce);
> 
> is it safe to do the put outside the xa_lock, in case the refcount goes to
> zero with this? I know it is unlikely because the refcount was > 0 if do_put
> is true, but it might've gone down between us checking earlier and now.
> 

It is safe as xa_for_each indicates it is safe to destroy / delete
objects from the array while traversing it. 

> > +		xa_lock(&guc->context_lookup);
> >   	}
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> >   }
> >   static inline bool
> > @@ -873,16 +891,29 @@ void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
> >   {
> >   	struct intel_context *ce;
> >   	unsigned long index;
> > +	unsigned long flags;
> >   	if (unlikely(!guc_submission_initialized(guc))) {
> >   		/* Reset called during driver load? GuC not yet initialised! */
> >   		return;
> >   	}
> > -	xa_for_each(&guc->context_lookup, index, ce)
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> > +	xa_for_each(&guc->context_lookup, index, ce) {
> > +		if (!kref_get_unless_zero(&ce->ref))
> > +			continue;
> > +
> > +		xa_unlock(&guc->context_lookup);
> > +
> >   		if (intel_context_is_pinned(ce))
> >   			__guc_reset_context(ce, stalled);
> > +		intel_context_put(ce);
> > +
> > +		xa_lock(&guc->context_lookup);
> > +	}
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> > +
> >   	/* GuC is blown away, drop all references to contexts */
> >   	xa_destroy(&guc->context_lookup);
> >   }
> > @@ -957,11 +988,24 @@ void intel_guc_submission_cancel_requests(struct intel_guc *guc)
> >   {
> >   	struct intel_context *ce;
> >   	unsigned long index;
> > +	unsigned long flags;
> > +
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> > +	xa_for_each(&guc->context_lookup, index, ce) {
> > +		if (!kref_get_unless_zero(&ce->ref))
> > +			continue;
> > +
> > +		xa_unlock(&guc->context_lookup);
> > -	xa_for_each(&guc->context_lookup, index, ce)
> >   		if (intel_context_is_pinned(ce))
> >   			guc_cancel_context_requests(ce);
> > +		intel_context_put(ce);
> > +
> > +		xa_lock(&guc->context_lookup);
> > +	}
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> > +
> >   	guc_cancel_sched_engine_requests(guc->sched_engine);
> >   	/* GuC is blown away, drop all references to contexts */
> > @@ -2850,21 +2894,28 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
> >   	struct intel_context *ce;
> >   	struct i915_request *rq;
> >   	unsigned long index;
> > +	unsigned long flags;
> >   	/* Reset called during driver load? GuC not yet initialised! */
> >   	if (unlikely(!guc_submission_initialized(guc)))
> >   		return;
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> >   	xa_for_each(&guc->context_lookup, index, ce) {
> > -		if (!intel_context_is_pinned(ce))
> > +		if (!kref_get_unless_zero(&ce->ref))
> >   			continue;
> > +		xa_unlock(&guc->context_lookup);
> > +
> > +		if (!intel_context_is_pinned(ce))
> > +			goto next;
> > +
> >   		if (intel_engine_is_virtual(ce->engine)) {
> >   			if (!(ce->engine->mask & engine->mask))
> > -				continue;
> > +				goto next;
> >   		} else {
> >   			if (ce->engine != engine)
> > -				continue;
> > +				goto next;
> >   		}
> >   		list_for_each_entry(rq, &ce->guc_active.requests, sched.link) {
> > @@ -2874,9 +2925,17 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
> >   			intel_engine_set_hung_context(engine, ce);
> >   			/* Can only cope with one hang at a time... */
> > -			return;
> > +			intel_context_put(ce);
> > +			xa_lock(&guc->context_lookup);
> > +			goto done;
> >   		}
> > +next:
> > +		intel_context_put(ce);
> > +		xa_lock(&guc->context_lookup);
> > +
> 
> nit: extra newline
> 

Checkpatch got that one too. Already fixed.

Matt

> Daniele
> 
> >   	}
> > +done:
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> >   }
> >   void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
> > @@ -2892,23 +2951,34 @@ void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
> >   	if (unlikely(!guc_submission_initialized(guc)))
> >   		return;
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> >   	xa_for_each(&guc->context_lookup, index, ce) {
> > -		if (!intel_context_is_pinned(ce))
> > +		if (!kref_get_unless_zero(&ce->ref))
> >   			continue;
> > +		xa_unlock(&guc->context_lookup);
> > +
> > +		if (!intel_context_is_pinned(ce))
> > +			goto next;
> > +
> >   		if (intel_engine_is_virtual(ce->engine)) {
> >   			if (!(ce->engine->mask & engine->mask))
> > -				continue;
> > +				goto next;
> >   		} else {
> >   			if (ce->engine != engine)
> > -				continue;
> > +				goto next;
> >   		}
> > -		spin_lock_irqsave(&ce->guc_active.lock, flags);
> > +		spin_lock(&ce->guc_active.lock);
> >   		intel_engine_dump_active_requests(&ce->guc_active.requests,
> >   						  hung_rq, m);
> > -		spin_unlock_irqrestore(&ce->guc_active.lock, flags);
> > +		spin_unlock(&ce->guc_active.lock);
> > +
> > +next:
> > +		intel_context_put(ce);
> > +		xa_lock(&guc->context_lookup);
> >   	}
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> >   }
> >   void intel_guc_submission_print_info(struct intel_guc *guc,
> > @@ -2962,7 +3032,9 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
> >   {
> >   	struct intel_context *ce;
> >   	unsigned long index;
> > +	unsigned long flags;
> > +	xa_lock_irqsave(&guc->context_lookup, flags);
> >   	xa_for_each(&guc->context_lookup, index, ce) {
> >   		drm_printf(p, "GuC lrc descriptor %u:\n", ce->guc_id);
> >   		drm_printf(p, "\tHW Context Desc: 0x%08x\n", ce->lrc.lrca);
> > @@ -2981,6 +3053,7 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
> >   		guc_log_context_priority(p, ce);
> >   	}
> > +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> >   }
> >   static struct intel_context *
>
Daniele Ceraolo Spurio Aug. 26, 2021, 12:44 a.m. UTC | #2
On 8/18/2021 11:16 PM, Matthew Brost wrote:
> Lock the xarray and take ref to the context if needed.
>
> v2:
>   (Checkpatch)
>    - Add new line after declaration
>   (Daniel Vetter)
>    - Correct put / get accounting in xa_for_loops
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 103 +++++++++++++++---
>   1 file changed, 88 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index 509b298e7cf3..5f77f25322ca 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -606,8 +606,18 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
>   	unsigned long index, flags;
>   	bool pending_disable, pending_enable, deregister, destroyed, banned;
>   
> +	xa_lock_irqsave(&guc->context_lookup, flags);
>   	xa_for_each(&guc->context_lookup, index, ce) {
> -		spin_lock_irqsave(&ce->guc_state.lock, flags);
> +		/*
> +		 * Corner case where the ref count on the object is zero but and
> +		 * deregister G2H was lost. In this case we don't touch the ref
> +		 * count and finish the destroy of the context.
> +		 */
> +		bool do_put = kref_get_unless_zero(&ce->ref);
> +
> +		xa_unlock(&guc->context_lookup);
> +
> +		spin_lock(&ce->guc_state.lock);
>   
>   		/*
>   		 * Once we are at this point submission_disabled() is guaranteed
> @@ -623,7 +633,9 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
>   		banned = context_banned(ce);
>   		init_sched_state(ce);
>   
> -		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +		spin_unlock(&ce->guc_state.lock);
> +
> +		GEM_BUG_ON(!do_put && !destroyed);
>   
>   		if (pending_enable || destroyed || deregister) {
>   			decr_outstanding_submission_g2h(guc);
> @@ -646,13 +658,19 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
>   			}
>   			intel_context_sched_disable_unpin(ce);
>   			decr_outstanding_submission_g2h(guc);
> -			spin_lock_irqsave(&ce->guc_state.lock, flags);
> +
> +			spin_lock(&ce->guc_state.lock);
>   			guc_blocked_fence_complete(ce);
> -			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +			spin_unlock(&ce->guc_state.lock);
>   
>   			intel_context_put(ce);
>   		}
> +
> +		if (do_put)
> +			intel_context_put(ce);

is it safe to do the put outside the xa_lock, in case the refcount goes 
to zero with this? I know it is unlikely because the refcount was > 0 if 
do_put is true, but it might've gone down between us checking earlier 
and now.

> +		xa_lock(&guc->context_lookup);
>   	}
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>   }
>   
>   static inline bool
> @@ -873,16 +891,29 @@ void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
>   {
>   	struct intel_context *ce;
>   	unsigned long index;
> +	unsigned long flags;
>   
>   	if (unlikely(!guc_submission_initialized(guc))) {
>   		/* Reset called during driver load? GuC not yet initialised! */
>   		return;
>   	}
>   
> -	xa_for_each(&guc->context_lookup, index, ce)
> +	xa_lock_irqsave(&guc->context_lookup, flags);
> +	xa_for_each(&guc->context_lookup, index, ce) {
> +		if (!kref_get_unless_zero(&ce->ref))
> +			continue;
> +
> +		xa_unlock(&guc->context_lookup);
> +
>   		if (intel_context_is_pinned(ce))
>   			__guc_reset_context(ce, stalled);
>   
> +		intel_context_put(ce);
> +
> +		xa_lock(&guc->context_lookup);
> +	}
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> +
>   	/* GuC is blown away, drop all references to contexts */
>   	xa_destroy(&guc->context_lookup);
>   }
> @@ -957,11 +988,24 @@ void intel_guc_submission_cancel_requests(struct intel_guc *guc)
>   {
>   	struct intel_context *ce;
>   	unsigned long index;
> +	unsigned long flags;
> +
> +	xa_lock_irqsave(&guc->context_lookup, flags);
> +	xa_for_each(&guc->context_lookup, index, ce) {
> +		if (!kref_get_unless_zero(&ce->ref))
> +			continue;
> +
> +		xa_unlock(&guc->context_lookup);
>   
> -	xa_for_each(&guc->context_lookup, index, ce)
>   		if (intel_context_is_pinned(ce))
>   			guc_cancel_context_requests(ce);
>   
> +		intel_context_put(ce);
> +
> +		xa_lock(&guc->context_lookup);
> +	}
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
> +
>   	guc_cancel_sched_engine_requests(guc->sched_engine);
>   
>   	/* GuC is blown away, drop all references to contexts */
> @@ -2850,21 +2894,28 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
>   	struct intel_context *ce;
>   	struct i915_request *rq;
>   	unsigned long index;
> +	unsigned long flags;
>   
>   	/* Reset called during driver load? GuC not yet initialised! */
>   	if (unlikely(!guc_submission_initialized(guc)))
>   		return;
>   
> +	xa_lock_irqsave(&guc->context_lookup, flags);
>   	xa_for_each(&guc->context_lookup, index, ce) {
> -		if (!intel_context_is_pinned(ce))
> +		if (!kref_get_unless_zero(&ce->ref))
>   			continue;
>   
> +		xa_unlock(&guc->context_lookup);
> +
> +		if (!intel_context_is_pinned(ce))
> +			goto next;
> +
>   		if (intel_engine_is_virtual(ce->engine)) {
>   			if (!(ce->engine->mask & engine->mask))
> -				continue;
> +				goto next;
>   		} else {
>   			if (ce->engine != engine)
> -				continue;
> +				goto next;
>   		}
>   
>   		list_for_each_entry(rq, &ce->guc_active.requests, sched.link) {
> @@ -2874,9 +2925,17 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
>   			intel_engine_set_hung_context(engine, ce);
>   
>   			/* Can only cope with one hang at a time... */
> -			return;
> +			intel_context_put(ce);
> +			xa_lock(&guc->context_lookup);
> +			goto done;
>   		}
> +next:
> +		intel_context_put(ce);
> +		xa_lock(&guc->context_lookup);
> +

nit: extra newline

Daniele

>   	}
> +done:
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>   }
>   
>   void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
> @@ -2892,23 +2951,34 @@ void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
>   	if (unlikely(!guc_submission_initialized(guc)))
>   		return;
>   
> +	xa_lock_irqsave(&guc->context_lookup, flags);
>   	xa_for_each(&guc->context_lookup, index, ce) {
> -		if (!intel_context_is_pinned(ce))
> +		if (!kref_get_unless_zero(&ce->ref))
>   			continue;
>   
> +		xa_unlock(&guc->context_lookup);
> +
> +		if (!intel_context_is_pinned(ce))
> +			goto next;
> +
>   		if (intel_engine_is_virtual(ce->engine)) {
>   			if (!(ce->engine->mask & engine->mask))
> -				continue;
> +				goto next;
>   		} else {
>   			if (ce->engine != engine)
> -				continue;
> +				goto next;
>   		}
>   
> -		spin_lock_irqsave(&ce->guc_active.lock, flags);
> +		spin_lock(&ce->guc_active.lock);
>   		intel_engine_dump_active_requests(&ce->guc_active.requests,
>   						  hung_rq, m);
> -		spin_unlock_irqrestore(&ce->guc_active.lock, flags);
> +		spin_unlock(&ce->guc_active.lock);
> +
> +next:
> +		intel_context_put(ce);
> +		xa_lock(&guc->context_lookup);
>   	}
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>   }
>   
>   void intel_guc_submission_print_info(struct intel_guc *guc,
> @@ -2962,7 +3032,9 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
>   {
>   	struct intel_context *ce;
>   	unsigned long index;
> +	unsigned long flags;
>   
> +	xa_lock_irqsave(&guc->context_lookup, flags);
>   	xa_for_each(&guc->context_lookup, index, ce) {
>   		drm_printf(p, "GuC lrc descriptor %u:\n", ce->guc_id);
>   		drm_printf(p, "\tHW Context Desc: 0x%08x\n", ce->lrc.lrca);
> @@ -2981,6 +3053,7 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
>   
>   		guc_log_context_priority(p, ce);
>   	}
> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>   }
>   
>   static struct intel_context *
Daniele Ceraolo Spurio Aug. 26, 2021, 12:48 a.m. UTC | #3
On 8/25/2021 5:41 PM, Matthew Brost wrote:
> On Wed, Aug 25, 2021 at 05:44:11PM -0700, Daniele Ceraolo Spurio wrote:
>>
>> On 8/18/2021 11:16 PM, Matthew Brost wrote:
>>> Lock the xarray and take ref to the context if needed.
>>>
>>> v2:
>>>    (Checkpatch)
>>>     - Add new line after declaration
>>>    (Daniel Vetter)
>>>     - Correct put / get accounting in xa_for_loops
>>>
>>> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
>>> ---
>>>    .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 103 +++++++++++++++---
>>>    1 file changed, 88 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> index 509b298e7cf3..5f77f25322ca 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> @@ -606,8 +606,18 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
>>>    	unsigned long index, flags;
>>>    	bool pending_disable, pending_enable, deregister, destroyed, banned;
>>> +	xa_lock_irqsave(&guc->context_lookup, flags);
>>>    	xa_for_each(&guc->context_lookup, index, ce) {
>>> -		spin_lock_irqsave(&ce->guc_state.lock, flags);
>>> +		/*
>>> +		 * Corner case where the ref count on the object is zero but and
>>> +		 * deregister G2H was lost. In this case we don't touch the ref
>>> +		 * count and finish the destroy of the context.
>>> +		 */
>>> +		bool do_put = kref_get_unless_zero(&ce->ref);
>>> +
>>> +		xa_unlock(&guc->context_lookup);
>>> +
>>> +		spin_lock(&ce->guc_state.lock);
>>>    		/*
>>>    		 * Once we are at this point submission_disabled() is guaranteed
>>> @@ -623,7 +633,9 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
>>>    		banned = context_banned(ce);
>>>    		init_sched_state(ce);
>>> -		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>>> +		spin_unlock(&ce->guc_state.lock);
>>> +
>>> +		GEM_BUG_ON(!do_put && !destroyed);
>>>    		if (pending_enable || destroyed || deregister) {
>>>    			decr_outstanding_submission_g2h(guc);
>>> @@ -646,13 +658,19 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
>>>    			}
>>>    			intel_context_sched_disable_unpin(ce);
>>>    			decr_outstanding_submission_g2h(guc);
>>> -			spin_lock_irqsave(&ce->guc_state.lock, flags);
>>> +
>>> +			spin_lock(&ce->guc_state.lock);
>>>    			guc_blocked_fence_complete(ce);
>>> -			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
>>> +			spin_unlock(&ce->guc_state.lock);
>>>    			intel_context_put(ce);
>>>    		}
>>> +
>>> +		if (do_put)
>>> +			intel_context_put(ce);
>> is it safe to do the put outside the xa_lock, in case the refcount goes to
>> zero with this? I know it is unlikely because the refcount was > 0 if do_put
>> is true, but it might've gone down between us checking earlier and now.
>>
> It is safe as xa_for_each indicates it is safe to destroy / delete
> objects from the array while traversing it.

ok.

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>

Daniele

>>> +		xa_lock(&guc->context_lookup);
>>>    	}
>>> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>>>    }
>>>    static inline bool
>>> @@ -873,16 +891,29 @@ void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
>>>    {
>>>    	struct intel_context *ce;
>>>    	unsigned long index;
>>> +	unsigned long flags;
>>>    	if (unlikely(!guc_submission_initialized(guc))) {
>>>    		/* Reset called during driver load? GuC not yet initialised! */
>>>    		return;
>>>    	}
>>> -	xa_for_each(&guc->context_lookup, index, ce)
>>> +	xa_lock_irqsave(&guc->context_lookup, flags);
>>> +	xa_for_each(&guc->context_lookup, index, ce) {
>>> +		if (!kref_get_unless_zero(&ce->ref))
>>> +			continue;
>>> +
>>> +		xa_unlock(&guc->context_lookup);
>>> +
>>>    		if (intel_context_is_pinned(ce))
>>>    			__guc_reset_context(ce, stalled);
>>> +		intel_context_put(ce);
>>> +
>>> +		xa_lock(&guc->context_lookup);
>>> +	}
>>> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>>> +
>>>    	/* GuC is blown away, drop all references to contexts */
>>>    	xa_destroy(&guc->context_lookup);
>>>    }
>>> @@ -957,11 +988,24 @@ void intel_guc_submission_cancel_requests(struct intel_guc *guc)
>>>    {
>>>    	struct intel_context *ce;
>>>    	unsigned long index;
>>> +	unsigned long flags;
>>> +
>>> +	xa_lock_irqsave(&guc->context_lookup, flags);
>>> +	xa_for_each(&guc->context_lookup, index, ce) {
>>> +		if (!kref_get_unless_zero(&ce->ref))
>>> +			continue;
>>> +
>>> +		xa_unlock(&guc->context_lookup);
>>> -	xa_for_each(&guc->context_lookup, index, ce)
>>>    		if (intel_context_is_pinned(ce))
>>>    			guc_cancel_context_requests(ce);
>>> +		intel_context_put(ce);
>>> +
>>> +		xa_lock(&guc->context_lookup);
>>> +	}
>>> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>>> +
>>>    	guc_cancel_sched_engine_requests(guc->sched_engine);
>>>    	/* GuC is blown away, drop all references to contexts */
>>> @@ -2850,21 +2894,28 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
>>>    	struct intel_context *ce;
>>>    	struct i915_request *rq;
>>>    	unsigned long index;
>>> +	unsigned long flags;
>>>    	/* Reset called during driver load? GuC not yet initialised! */
>>>    	if (unlikely(!guc_submission_initialized(guc)))
>>>    		return;
>>> +	xa_lock_irqsave(&guc->context_lookup, flags);
>>>    	xa_for_each(&guc->context_lookup, index, ce) {
>>> -		if (!intel_context_is_pinned(ce))
>>> +		if (!kref_get_unless_zero(&ce->ref))
>>>    			continue;
>>> +		xa_unlock(&guc->context_lookup);
>>> +
>>> +		if (!intel_context_is_pinned(ce))
>>> +			goto next;
>>> +
>>>    		if (intel_engine_is_virtual(ce->engine)) {
>>>    			if (!(ce->engine->mask & engine->mask))
>>> -				continue;
>>> +				goto next;
>>>    		} else {
>>>    			if (ce->engine != engine)
>>> -				continue;
>>> +				goto next;
>>>    		}
>>>    		list_for_each_entry(rq, &ce->guc_active.requests, sched.link) {
>>> @@ -2874,9 +2925,17 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
>>>    			intel_engine_set_hung_context(engine, ce);
>>>    			/* Can only cope with one hang at a time... */
>>> -			return;
>>> +			intel_context_put(ce);
>>> +			xa_lock(&guc->context_lookup);
>>> +			goto done;
>>>    		}
>>> +next:
>>> +		intel_context_put(ce);
>>> +		xa_lock(&guc->context_lookup);
>>> +
>> nit: extra newline
>>
> Checkpatch got that one too. Already fixed.
>
> Matt
>
>> Daniele
>>
>>>    	}
>>> +done:
>>> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>>>    }
>>>    void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
>>> @@ -2892,23 +2951,34 @@ void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
>>>    	if (unlikely(!guc_submission_initialized(guc)))
>>>    		return;
>>> +	xa_lock_irqsave(&guc->context_lookup, flags);
>>>    	xa_for_each(&guc->context_lookup, index, ce) {
>>> -		if (!intel_context_is_pinned(ce))
>>> +		if (!kref_get_unless_zero(&ce->ref))
>>>    			continue;
>>> +		xa_unlock(&guc->context_lookup);
>>> +
>>> +		if (!intel_context_is_pinned(ce))
>>> +			goto next;
>>> +
>>>    		if (intel_engine_is_virtual(ce->engine)) {
>>>    			if (!(ce->engine->mask & engine->mask))
>>> -				continue;
>>> +				goto next;
>>>    		} else {
>>>    			if (ce->engine != engine)
>>> -				continue;
>>> +				goto next;
>>>    		}
>>> -		spin_lock_irqsave(&ce->guc_active.lock, flags);
>>> +		spin_lock(&ce->guc_active.lock);
>>>    		intel_engine_dump_active_requests(&ce->guc_active.requests,
>>>    						  hung_rq, m);
>>> -		spin_unlock_irqrestore(&ce->guc_active.lock, flags);
>>> +		spin_unlock(&ce->guc_active.lock);
>>> +
>>> +next:
>>> +		intel_context_put(ce);
>>> +		xa_lock(&guc->context_lookup);
>>>    	}
>>> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>>>    }
>>>    void intel_guc_submission_print_info(struct intel_guc *guc,
>>> @@ -2962,7 +3032,9 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
>>>    {
>>>    	struct intel_context *ce;
>>>    	unsigned long index;
>>> +	unsigned long flags;
>>> +	xa_lock_irqsave(&guc->context_lookup, flags);
>>>    	xa_for_each(&guc->context_lookup, index, ce) {
>>>    		drm_printf(p, "GuC lrc descriptor %u:\n", ce->guc_id);
>>>    		drm_printf(p, "\tHW Context Desc: 0x%08x\n", ce->lrc.lrca);
>>> @@ -2981,6 +3053,7 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
>>>    		guc_log_context_priority(p, ce);
>>>    	}
>>> +	xa_unlock_irqrestore(&guc->context_lookup, flags);
>>>    }
>>>    static struct intel_context *
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 509b298e7cf3..5f77f25322ca 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -606,8 +606,18 @@  static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
 	unsigned long index, flags;
 	bool pending_disable, pending_enable, deregister, destroyed, banned;
 
+	xa_lock_irqsave(&guc->context_lookup, flags);
 	xa_for_each(&guc->context_lookup, index, ce) {
-		spin_lock_irqsave(&ce->guc_state.lock, flags);
+		/*
+		 * Corner case where the ref count on the object is zero but and
+		 * deregister G2H was lost. In this case we don't touch the ref
+		 * count and finish the destroy of the context.
+		 */
+		bool do_put = kref_get_unless_zero(&ce->ref);
+
+		xa_unlock(&guc->context_lookup);
+
+		spin_lock(&ce->guc_state.lock);
 
 		/*
 		 * Once we are at this point submission_disabled() is guaranteed
@@ -623,7 +633,9 @@  static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
 		banned = context_banned(ce);
 		init_sched_state(ce);
 
-		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+		spin_unlock(&ce->guc_state.lock);
+
+		GEM_BUG_ON(!do_put && !destroyed);
 
 		if (pending_enable || destroyed || deregister) {
 			decr_outstanding_submission_g2h(guc);
@@ -646,13 +658,19 @@  static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
 			}
 			intel_context_sched_disable_unpin(ce);
 			decr_outstanding_submission_g2h(guc);
-			spin_lock_irqsave(&ce->guc_state.lock, flags);
+
+			spin_lock(&ce->guc_state.lock);
 			guc_blocked_fence_complete(ce);
-			spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+			spin_unlock(&ce->guc_state.lock);
 
 			intel_context_put(ce);
 		}
+
+		if (do_put)
+			intel_context_put(ce);
+		xa_lock(&guc->context_lookup);
 	}
+	xa_unlock_irqrestore(&guc->context_lookup, flags);
 }
 
 static inline bool
@@ -873,16 +891,29 @@  void intel_guc_submission_reset(struct intel_guc *guc, bool stalled)
 {
 	struct intel_context *ce;
 	unsigned long index;
+	unsigned long flags;
 
 	if (unlikely(!guc_submission_initialized(guc))) {
 		/* Reset called during driver load? GuC not yet initialised! */
 		return;
 	}
 
-	xa_for_each(&guc->context_lookup, index, ce)
+	xa_lock_irqsave(&guc->context_lookup, flags);
+	xa_for_each(&guc->context_lookup, index, ce) {
+		if (!kref_get_unless_zero(&ce->ref))
+			continue;
+
+		xa_unlock(&guc->context_lookup);
+
 		if (intel_context_is_pinned(ce))
 			__guc_reset_context(ce, stalled);
 
+		intel_context_put(ce);
+
+		xa_lock(&guc->context_lookup);
+	}
+	xa_unlock_irqrestore(&guc->context_lookup, flags);
+
 	/* GuC is blown away, drop all references to contexts */
 	xa_destroy(&guc->context_lookup);
 }
@@ -957,11 +988,24 @@  void intel_guc_submission_cancel_requests(struct intel_guc *guc)
 {
 	struct intel_context *ce;
 	unsigned long index;
+	unsigned long flags;
+
+	xa_lock_irqsave(&guc->context_lookup, flags);
+	xa_for_each(&guc->context_lookup, index, ce) {
+		if (!kref_get_unless_zero(&ce->ref))
+			continue;
+
+		xa_unlock(&guc->context_lookup);
 
-	xa_for_each(&guc->context_lookup, index, ce)
 		if (intel_context_is_pinned(ce))
 			guc_cancel_context_requests(ce);
 
+		intel_context_put(ce);
+
+		xa_lock(&guc->context_lookup);
+	}
+	xa_unlock_irqrestore(&guc->context_lookup, flags);
+
 	guc_cancel_sched_engine_requests(guc->sched_engine);
 
 	/* GuC is blown away, drop all references to contexts */
@@ -2850,21 +2894,28 @@  void intel_guc_find_hung_context(struct intel_engine_cs *engine)
 	struct intel_context *ce;
 	struct i915_request *rq;
 	unsigned long index;
+	unsigned long flags;
 
 	/* Reset called during driver load? GuC not yet initialised! */
 	if (unlikely(!guc_submission_initialized(guc)))
 		return;
 
+	xa_lock_irqsave(&guc->context_lookup, flags);
 	xa_for_each(&guc->context_lookup, index, ce) {
-		if (!intel_context_is_pinned(ce))
+		if (!kref_get_unless_zero(&ce->ref))
 			continue;
 
+		xa_unlock(&guc->context_lookup);
+
+		if (!intel_context_is_pinned(ce))
+			goto next;
+
 		if (intel_engine_is_virtual(ce->engine)) {
 			if (!(ce->engine->mask & engine->mask))
-				continue;
+				goto next;
 		} else {
 			if (ce->engine != engine)
-				continue;
+				goto next;
 		}
 
 		list_for_each_entry(rq, &ce->guc_active.requests, sched.link) {
@@ -2874,9 +2925,17 @@  void intel_guc_find_hung_context(struct intel_engine_cs *engine)
 			intel_engine_set_hung_context(engine, ce);
 
 			/* Can only cope with one hang at a time... */
-			return;
+			intel_context_put(ce);
+			xa_lock(&guc->context_lookup);
+			goto done;
 		}
+next:
+		intel_context_put(ce);
+		xa_lock(&guc->context_lookup);
+
 	}
+done:
+	xa_unlock_irqrestore(&guc->context_lookup, flags);
 }
 
 void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
@@ -2892,23 +2951,34 @@  void intel_guc_dump_active_requests(struct intel_engine_cs *engine,
 	if (unlikely(!guc_submission_initialized(guc)))
 		return;
 
+	xa_lock_irqsave(&guc->context_lookup, flags);
 	xa_for_each(&guc->context_lookup, index, ce) {
-		if (!intel_context_is_pinned(ce))
+		if (!kref_get_unless_zero(&ce->ref))
 			continue;
 
+		xa_unlock(&guc->context_lookup);
+
+		if (!intel_context_is_pinned(ce))
+			goto next;
+
 		if (intel_engine_is_virtual(ce->engine)) {
 			if (!(ce->engine->mask & engine->mask))
-				continue;
+				goto next;
 		} else {
 			if (ce->engine != engine)
-				continue;
+				goto next;
 		}
 
-		spin_lock_irqsave(&ce->guc_active.lock, flags);
+		spin_lock(&ce->guc_active.lock);
 		intel_engine_dump_active_requests(&ce->guc_active.requests,
 						  hung_rq, m);
-		spin_unlock_irqrestore(&ce->guc_active.lock, flags);
+		spin_unlock(&ce->guc_active.lock);
+
+next:
+		intel_context_put(ce);
+		xa_lock(&guc->context_lookup);
 	}
+	xa_unlock_irqrestore(&guc->context_lookup, flags);
 }
 
 void intel_guc_submission_print_info(struct intel_guc *guc,
@@ -2962,7 +3032,9 @@  void intel_guc_submission_print_context_info(struct intel_guc *guc,
 {
 	struct intel_context *ce;
 	unsigned long index;
+	unsigned long flags;
 
+	xa_lock_irqsave(&guc->context_lookup, flags);
 	xa_for_each(&guc->context_lookup, index, ce) {
 		drm_printf(p, "GuC lrc descriptor %u:\n", ce->guc_id);
 		drm_printf(p, "\tHW Context Desc: 0x%08x\n", ce->lrc.lrca);
@@ -2981,6 +3053,7 @@  void intel_guc_submission_print_context_info(struct intel_guc *guc,
 
 		guc_log_context_priority(p, ce);
 	}
+	xa_unlock_irqrestore(&guc->context_lookup, flags);
 }
 
 static struct intel_context *