Lock the xarray and take ref to the context if needed.

Signed-off-by: Matthew Brost <matthew.br...@intel.com>
---
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 83 ++++++++++++++++---
 1 file changed, 72 insertions(+), 11 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 d3f1d8ca0396..4120d1a3c065 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -599,8 +599,17 @@ 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
@@ -616,7 +625,9 @@ 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) {
                        atomic_dec(&guc->outstanding_submission_g2h);
@@ -645,7 +656,12 @@ static void scrub_guc_desc_for_outstanding_g2h(struct 
intel_guc *guc)
 
                        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
@@ -865,16 +881,26 @@ 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) {
+               intel_context_get(ce);
+               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);
 }
@@ -949,11 +975,21 @@ 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) {
+               intel_context_get(ce);
+               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 */
@@ -2847,21 +2883,26 @@ 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) {
+               intel_context_get(ce);
+               xa_unlock(&guc->context_lookup);
+
                if (!intel_context_is_pinned(ce))
-                       continue;
+                       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) {
@@ -2871,9 +2912,17 @@ 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,
@@ -2889,23 +2938,32 @@ 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) {
+               intel_context_get(ce);
+               xa_unlock(&guc->context_lookup);
+
                if (!intel_context_is_pinned(ce))
-                       continue;
+                       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);
                intel_engine_dump_active_requests(&ce->guc_active.requests,
                                                  hung_rq, m);
                spin_unlock_irqrestore(&ce->guc_active.lock, flags);
+
+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,
@@ -2959,7 +3017,9 @@ 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);
@@ -2978,6 +3038,7 @@ 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 *
-- 
2.32.0

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