From 6619160beb07804d9f576c336aaa75932f91e12a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Si=C3=A2n=20James?= <sian.james@amd.com>
Date: Tue, 12 Nov 2024 14:47:49 +0000
Subject: [PATCH] ON-16118: Add basic refcounting for RXQs

---
 src/include/ci/efhw/ef10ct.h     |  4 +---
 src/lib/efhw/ef10ct/aux_ef10ct.c |  4 +---
 src/lib/efhw/ef10ct/ef10ct.c     | 31 +++++++++++++++++++++++--------
 3 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/src/include/ci/efhw/ef10ct.h b/src/include/ci/efhw/ef10ct.h
index 681ab103..075ab8de 100644
--- a/src/include/ci/efhw/ef10ct.h
+++ b/src/include/ci/efhw/ef10ct.h
@@ -26,9 +26,7 @@ struct efhw_nic_ef10ct_evq {
 
 struct efhw_nic_ef10ct_rxq {
   int evq;
-  /* ID of the software vi that is bound to this hardware rxq */
-  /* TODO: Does this need to be expanded for shared rxqs? */
-  int q_id;
+  int ref_count;
   uint64_t *post_buffer_addr;
 };
 
diff --git a/src/lib/efhw/ef10ct/aux_ef10ct.c b/src/lib/efhw/ef10ct/aux_ef10ct.c
index 0214295a..46de597e 100644
--- a/src/lib/efhw/ef10ct/aux_ef10ct.c
+++ b/src/lib/efhw/ef10ct/aux_ef10ct.c
@@ -104,10 +104,8 @@ static int ef10ct_resource_init(struct efx_auxdev *edev,
     rc = -ENOMEM;
     goto fail1;
   }
-  for( i = 0; i < ef10ct->rxq_n; i++ ) {
+  for( i = 0; i < ef10ct->rxq_n; i++ )
     ef10ct->rxq[i].evq = -1;
-    ef10ct->rxq[i].q_id = -1;
-  }
 
   res_dim->irq_n_ranges = 0;
 #if 0
diff --git a/src/lib/efhw/ef10ct/ef10ct.c b/src/lib/efhw/ef10ct/ef10ct.c
index 3dc6fd2d..7accbf97 100644
--- a/src/lib/efhw/ef10ct/ef10ct.c
+++ b/src/lib/efhw/ef10ct/ef10ct.c
@@ -171,11 +171,6 @@ static void ef10ct_check_for_flushes(struct work_struct *work)
       if(CI_QWORD_FIELD(*event, EFCT_FLUSH_TYPE) == EFCT_FLUSH_TYPE_TX) {
         efhw_handle_txdmaq_flushed(evq->nic, q_id);
       } else /* EFCT_FLUSH_TYPE_RX */ {
-        struct efhw_nic_ef10ct *ef10ct = evq->nic->arch_extra;
-        int hw_rxq = q_id;
-
-        q_id = ef10ct->rxq[hw_rxq].q_id;
-        ef10ct->rxq[hw_rxq].q_id = -1;
         ef10ct_free_rxq(evq->nic, q_id);
         /* RXQ flush is not reported upwards. The HW RXQ is managed within
          * efhw. */
@@ -565,6 +560,21 @@ ef10ct_shared_rxq_bind(struct efhw_nic* nic,
   EFHW_WARN("%s: evq %d, rxq %d", __func__, params->wakeup_instance,
             params->qid);
 
+
+  /* FIXME EF10CT basic ref counting to avoid breaking shared queues while
+   * this is properly dealt with. At a minimum we need to ensure this is
+   * concurrency safe, but the details of lifecycle management need more
+   * consideration in general. */
+  if( ef10ct->rxq[rxq].ref_count > 0 ) {
+    /* This queue is already bound, so all that's needed is to inc the refs. */
+    ef10ct->rxq[rxq].ref_count++;
+
+    /* Already bound, so should have an associated evq */
+    EFHW_ASSERT(ef10ct->rxq[rxq].evq >= 0);
+
+    return 0;
+  }
+
   /* FIXME EF10CT the evq used here is not mapped to userspace, so isn't part
    * of the higher level resource management. We need to decide what evq to
    * attach to - a shared queue with rx event suppression, or a dedicated
@@ -601,10 +611,9 @@ ef10ct_shared_rxq_bind(struct efhw_nic* nic,
 
   flush_delayed_work(&ef10ct->evq[rxq_params.evq].check_flushes);
   EFHW_ASSERT(ef10ct->rxq[rxq].evq == -1);
-  EFHW_ASSERT(ef10ct->rxq[rxq].q_id == -1);
 
+  ef10ct->rxq[rxq].ref_count++;
   ef10ct->rxq[rxq].evq = rxq_params.evq;
-  ef10ct->rxq[rxq].q_id = rxq;
   params->rxq->qid = rxq;
 
   return rc;
@@ -620,7 +629,13 @@ ef10ct_shared_rxq_unbind(struct efhw_nic* nic, struct efhw_efct_rxq *rxq,
   struct efhw_nic_ef10ct_evq *ef10ct_evq;
   int dmaq = rxq->qid;
 
-  /* FIXME EF10CT this needs to be done based on ref count of users */
+  /* FIXME EF10CT proper refcounting */
+  EFHW_ASSERT(ef10ct->rxq[dmaq].ref_count > 0);
+  ef10ct->rxq[dmaq].ref_count--;
+
+  if( ef10ct->rxq[dmaq].ref_count > 0 )
+    return;
+
   /* FIXME EF10CT check errors here */
 
   dummy.cmd = MC_CMD_FINI_RXQ;