virtio: fix txq locking

Initialize txq lock only if some txq are shared and check if another
worker is already operating on the txq before processing gro timeouts
in input node.

Type: fix

Change-Id: I89dab6c0e6eb6a7aa621fa1548b0a2c76e6c7581
Signed-off-by: Benoît Ganne <bganne@cisco.com>
(cherry picked from commit b6b484d01adb8ab2ef5a50d5a3d6f3f097df2e0c)

3 files changed, 23 insertions, 2 deletions

diff --git a/src/vnet/devices/virtio/node.c b/src/vnet/devices/virtio/node.c
index 7fabe36401c..1c9cfd0cc03 100644
--- a/src/vnet/devices/virtio/node.c
+++ b/src/vnet/devices/virtio/node.c
@@ -279,10 +279,12 @@ virtio_device_input_gso_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
   u16 last = vring->last_used_idx;
   u16 n_left = vring->used->idx - last;
 
-  if (vif->packet_coalesce)
+  if (vif->packet_coalesce
+      && clib_spinlock_trylock_if_init (&txq_vring->lockp))
     {
       vnet_gro_flow_table_schedule_node_on_dispatcher (vm,
 						       txq_vring->flow_table);
+      clib_spinlock_unlock_if_init (&txq_vring->lockp);
     }
 
   if ((vring->used->flags & VRING_USED_F_NO_NOTIFY) == 0 &&
diff --git a/src/vnet/devices/virtio/pci.c b/src/vnet/devices/virtio/pci.c
index 5ba9f36de81..df8e2bdaf68 100644
--- a/src/vnet/devices/virtio/pci.c
+++ b/src/vnet/devices/virtio/pci.c
@@ -494,6 +494,7 @@ virtio_pci_control_vring_init (vlib_main_t * vm, virtio_if_t * vif,
 clib_error_t *
 virtio_pci_vring_init (vlib_main_t * vm, virtio_if_t * vif, u16 queue_num)
 {
+  vlib_thread_main_t *vtm = vlib_get_thread_main ();
   clib_error_t *error = 0;
   u16 queue_size = 0;
   virtio_vring_t *vring;
@@ -519,7 +520,8 @@ virtio_pci_vring_init (vlib_main_t * vm, virtio_if_t * vif, u16 queue_num)
       vec_validate_aligned (vif->txq_vrings, TX_QUEUE_ACCESS (queue_num),
 			    CLIB_CACHE_LINE_BYTES);
       vring = vec_elt_at_index (vif->txq_vrings, TX_QUEUE_ACCESS (queue_num));
-      clib_spinlock_init (&vring->lockp);
+      if (vif->max_queue_pairs < vtm->n_vlib_mains)
+	clib_spinlock_init (&vring->lockp);
     }
   else
     {
diff --git a/src/vppinfra/lock.h b/src/vppinfra/lock.h
index 3cfe11cba17..470890b6ec7 100644
--- a/src/vppinfra/lock.h
+++ b/src/vppinfra/lock.h
@@ -91,6 +91,15 @@ clib_spinlock_lock (clib_spinlock_t * p)
   CLIB_LOCK_DBG (p);
 }
 
+static_always_inline int
+clib_spinlock_trylock (clib_spinlock_t * p)
+{
+  if (PREDICT_FALSE (CLIB_SPINLOCK_IS_LOCKED (p)))
+    return 0;
+  clib_spinlock_lock (p);
+  return 1;
+}
+
 static_always_inline void
 clib_spinlock_lock_if_init (clib_spinlock_t * p)
 {
@@ -98,6 +107,14 @@ clib_spinlock_lock_if_init (clib_spinlock_t * p)
     clib_spinlock_lock (p);
 }
 
+static_always_inline int
+clib_spinlock_trylock_if_init (clib_spinlock_t * p)
+{
+  if (PREDICT_FALSE (*p != 0))
+    return clib_spinlock_trylock (p);
+  return 1;
+}
+
 static_always_inline void
 clib_spinlock_unlock (clib_spinlock_t * p)
 {