[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 00:44:11 UTC 2021
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.
> + 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 *
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