[Intel-gfx] [PATCH 21/27] drm/i915/guc: Proper xarray usage for contexts_lookup
Daniele Ceraolo Spurio
daniele.ceraolospurio at intel.com
Thu Aug 26 00:48:15 UTC 2021
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 at 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 at 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 *
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