X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvcl%2Fvcl_locked.c;h=d69d391d626bb5f7a6d188ae90b403f65d994065;hb=b020806806c0e6c54886cdb4347a5fd1f19504b0;hp=c6c79cdd470eb8baf7f43492ea781922a4253be1;hpb=f9240dc9207b677038183ca29888d4be89bb88d5;p=vpp.git

diff --git a/src/vcl/vcl_locked.c b/src/vcl/vcl_locked.c
index c6c79cdd470..d69d391d626 100644
--- a/src/vcl/vcl_locked.c
+++ b/src/vcl/vcl_locked.c
@@ -22,19 +22,31 @@ typedef struct vcl_locked_session_
   u32 session_index;
   u32 worker_index;
   u32 vls_index;
-  u32 flags;
   u32 *workers_subscribed;
+  clib_bitmap_t *listeners;
 } vcl_locked_session_t;
 
-typedef struct vcl_main_
+typedef struct vls_local_
+{
+  int vls_wrk_index;
+  volatile int vls_mt_n_threads;
+  pthread_mutex_t vls_mt_mq_mlock;
+  pthread_mutex_t vls_mt_spool_mlock;
+  volatile u8 select_mp_check;
+  volatile u8 epoll_mp_check;
+} vls_process_local_t;
+
+static vls_process_local_t vls_local;
+static vls_process_local_t *vlsl = &vls_local;
+
+typedef struct vls_main_
 {
   vcl_locked_session_t *vls_pool;
   clib_rwlock_t vls_table_lock;
   uword *session_index_to_vlsh_table;
 } vls_main_t;
 
-vls_main_t vls_main;
-vls_main_t *vlsm = &vls_main;
+vls_main_t *vlsm;
 
 static inline void
 vls_table_rlock (void)
@@ -60,6 +72,58 @@ vls_table_wunlock (void)
   clib_rwlock_writer_unlock (&vlsm->vls_table_lock);
 }
 
+typedef enum
+{
+  VLS_MT_OP_READ,
+  VLS_MT_OP_WRITE,
+  VLS_MT_OP_SPOOL,
+  VLS_MT_OP_XPOLL,
+} vls_mt_ops_t;
+
+typedef enum
+{
+  VLS_MT_LOCK_MQ = 1 << 0,
+  VLS_MT_LOCK_SPOOL = 1 << 1
+} vls_mt_lock_type_t;
+
+static void
+vls_mt_add (void)
+{
+  vlsl->vls_mt_n_threads += 1;
+  vcl_set_worker_index (vlsl->vls_wrk_index);
+}
+
+static inline void
+vls_mt_mq_lock (void)
+{
+  pthread_mutex_lock (&vlsl->vls_mt_mq_mlock);
+}
+
+static inline void
+vls_mt_mq_unlock (void)
+{
+  pthread_mutex_unlock (&vlsl->vls_mt_mq_mlock);
+}
+
+static inline void
+vls_mt_spool_lock (void)
+{
+  pthread_mutex_lock (&vlsl->vls_mt_spool_mlock);
+}
+
+static inline void
+vls_mt_create_unlock (void)
+{
+  pthread_mutex_unlock (&vlsl->vls_mt_spool_mlock);
+}
+
+static void
+vls_mt_locks_init (void)
+{
+  pthread_mutex_init (&vlsl->vls_mt_mq_mlock, NULL);
+  pthread_mutex_init (&vlsl->vls_mt_spool_mlock, NULL);
+}
+
 static inline vcl_session_handle_t
 vls_to_sh (vcl_locked_session_t * vls)
 {
@@ -101,12 +165,12 @@ vls_get (vls_handle_t vlsh)
 }
 
 static void
-vls_free (vcl_locked_session_t * fde)
+vls_free (vcl_locked_session_t * vls)
 {
-  ASSERT (fde != 0);
-  hash_unset (vlsm->session_index_to_vlsh_table, fde->session_index);
-  clib_spinlock_free (&fde->lock);
-  pool_put (vlsm->vls_pool, fde);
+  ASSERT (vls != 0);
+  hash_unset (vlsm->session_index_to_vlsh_table, vls->session_index);
+  clib_spinlock_free (&vls->lock);
+  pool_put (vlsm->vls_pool, vls);
 }
 
 static vcl_locked_session_t *
@@ -131,6 +195,12 @@ vls_get_w_dlock (vls_handle_t vlsh)
   return vls;
 }
 
+static inline void
+vls_lock (vcl_locked_session_t * vls)
+{
+  clib_spinlock_lock (&vls->lock);
+}
+
 static inline void
 vls_unlock (vcl_locked_session_t * vls)
 {
@@ -154,15 +224,46 @@ vls_dunlock (vcl_locked_session_t * vls)
   vls_table_runlock ();
 }
 
-static void
-vls_get_and_free (vls_handle_t vlsh)
+vcl_session_handle_t
+vlsh_to_sh (vls_handle_t vlsh)
 {
   vcl_locked_session_t *vls;
+  int rv;
 
-  vls_table_wlock ();
-  vls = vls_get (vlsh);
-  vls_free (vls);
-  vls_table_wunlock ();
+  vls = vls_get_w_dlock (vlsh);
+  if (!vls)
+    return INVALID_SESSION_ID;
+  rv = vls_to_sh (vls);
+  vls_dunlock (vls);
+  return rv;
+}
+
+vcl_session_handle_t
+vlsh_to_session_index (vls_handle_t vlsh)
+{
+  vcl_session_handle_t sh;
+  sh = vlsh_to_sh (vlsh);
+  return vppcom_session_index (sh);
+}
+
+vls_handle_t
+vls_si_to_vlsh (u32 session_index)
+{
+  uword *vlshp;
+  vlshp = hash_get (vlsm->session_index_to_vlsh_table, session_index);
+  return vlshp ? *vlshp : VLS_INVALID_HANDLE;
+}
+
+vls_handle_t
+vls_session_index_to_vlsh (uint32_t session_index)
+{
+  vls_handle_t vlsh;
+
+  vls_table_rlock ();
+  vlsh = vls_si_to_vlsh (session_index);
+  vls_table_runlock ();
+
+  return vlsh;
 }
 
 u8
@@ -171,41 +272,94 @@ vls_is_shared (vcl_locked_session_t * vls)
   return vec_len (vls->workers_subscribed);
 }
 
+u8
+vls_is_shared_by_wrk (vcl_locked_session_t * vls, u32 wrk_index)
+{
+  int i;
+  for (i = 0; i < vec_len (vls->workers_subscribed); i++)
+    if (vls->workers_subscribed[i] == wrk_index)
+      return 1;
+  return 0;
+}
+
+static void
+vls_listener_wrk_set (vcl_locked_session_t * vls, u32 wrk_index, u8 is_active)
+{
+  clib_bitmap_set (vls->listeners, wrk_index, is_active);
+}
+
+static u8
+vls_listener_wrk_is_active (vcl_locked_session_t * vls, u32 wrk_index)
+{
+  return (clib_bitmap_get (vls->listeners, wrk_index) == 1);
+}
+
+static void
+vls_listener_wrk_start_listen (vcl_locked_session_t * vls, u32 wrk_index)
+{
+  vppcom_session_listen (vls_to_sh (vls), ~0);
+  vls_listener_wrk_set (vls, wrk_index, 1 /* is_active */ );
+}
+
+static void
+vls_listener_wrk_stop_listen (vcl_locked_session_t * vls, u32 wrk_index)
+{
+  vcl_worker_t *wrk;
+  vcl_session_t *s;
+
+  wrk = vcl_worker_get (wrk_index);
+  s = vcl_session_get (wrk, vls->session_index);
+  if (s->session_state != STATE_LISTEN)
+    return;
+  vcl_send_session_unlisten (wrk, s);
+  s->session_state = STATE_LISTEN_NO_MQ;
+  vls_listener_wrk_set (vls, wrk_index, 0 /* is_active */ );
+}
+
 int
-vls_unshare_session (vcl_locked_session_t * vls)
+vls_unshare_session (vcl_locked_session_t * vls, vcl_worker_t * wrk)
 {
-  vcl_worker_t *wrk = vcl_worker_get_current ();
+  int i, do_disconnect;
   vcl_session_t *s;
-  int i;
+
+  s = vcl_session_get (wrk, vls->session_index);
+  if (s->session_state == STATE_LISTEN)
+    vls_listener_wrk_set (vls, wrk->wrk_index, 0 /* is_active */ );
 
   for (i = 0; i < vec_len (vls->workers_subscribed); i++)
     {
       if (vls->workers_subscribed[i] != wrk->wrk_index)
 	continue;
 
-      s = vcl_session_get (wrk, vls->session_index);
       if (s->rx_fifo)
 	{
 	  svm_fifo_del_subscriber (s->rx_fifo, wrk->vpp_wrk_index);
 	  svm_fifo_del_subscriber (s->tx_fifo, wrk->vpp_wrk_index);
 	}
       vec_del1 (vls->workers_subscribed, i);
-      vcl_session_cleanup (wrk, s, vcl_session_handle (s),
-			   0 /* do_disconnect */ );
+      do_disconnect = s->session_state == STATE_LISTEN;
+      vcl_session_cleanup (wrk, s, vcl_session_handle (s), do_disconnect);
       return 0;
     }
 
-  /* Assumption is that unshare is only called if session is shared.
-   * So shared_workers must be non-empty if the worker is the owner */
-  if (vls->worker_index == wrk->wrk_index)
+  /* Return, if this is not the owning worker */
+  if (vls->worker_index != wrk->wrk_index)
+    return 0;
+
+  /* Check if we can change owner or close */
+  if (vec_len (vls->workers_subscribed))
     {
-      s = vcl_session_get (wrk, vls->session_index);
       vls->worker_index = vls->workers_subscribed[0];
       vec_del1 (vls->workers_subscribed, 0);
       vcl_send_session_worker_update (wrk, s, vls->worker_index);
       if (vec_len (vls->workers_subscribed))
 	clib_warning ("more workers need to be updated");
     }
+  else
+    {
+      vcl_session_cleanup (wrk, s, vcl_session_handle (s),
+			   1 /* do_disconnect */ );
+    }
 
   return 0;
 }
@@ -215,16 +369,22 @@ vls_share_vcl_session (vcl_worker_t * wrk, vcl_session_t * s)
 {
   vcl_locked_session_t *vls;
 
-  vls = vls_get_w_dlock (vls_session_index_to_vlsh (s->session_index));
+  vls = vls_get (vls_si_to_vlsh (s->session_index));
   if (!vls)
     return;
+  vls_lock (vls);
   vec_add1 (vls->workers_subscribed, wrk->wrk_index);
   if (s->rx_fifo)
     {
       svm_fifo_add_subscriber (s->rx_fifo, wrk->vpp_wrk_index);
       svm_fifo_add_subscriber (s->tx_fifo, wrk->vpp_wrk_index);
     }
-  vls_dunlock (vls);
+  else if (s->session_state == STATE_LISTEN)
+    {
+      s->session_state = STATE_LISTEN_NO_MQ;
+    }
+
+  vls_unlock (vls);
 }
 
 void
@@ -237,14 +397,86 @@ vls_worker_copy_on_fork (vcl_worker_t * parent_wrk)
   wrk->sessions = pool_dup (parent_wrk->sessions);
   wrk->session_index_by_vpp_handles =
     hash_dup (parent_wrk->session_index_by_vpp_handles);
+  vls_table_rlock ();
 
   /* *INDENT-OFF* */
   pool_foreach (s, wrk->sessions, ({
     vls_share_vcl_session (wrk, s);
   }));
   /* *INDENT-ON* */
+
+  vls_table_runlock ();
 }
 
+static void
+vls_mt_acq_locks (vcl_locked_session_t * vls, vls_mt_ops_t op, int *locks_acq)
+{
+  vcl_worker_t *wrk = vcl_worker_get_current ();
+  vcl_session_t *s = 0;
+  int is_nonblk = 0;
+
+  if (vls)
+    {
+      s = vcl_session_get (wrk, vls->session_index);
+      if (PREDICT_FALSE (!s))
+	return;
+      is_nonblk = VCL_SESS_ATTR_TEST (s->attr, VCL_SESS_ATTR_NONBLOCK);
+    }
+
+  switch (op)
+    {
+    case VLS_MT_OP_READ:
+      if (!is_nonblk)
+	is_nonblk = vcl_session_read_ready (s) != 0;
+      if (!is_nonblk)
+	{
+	  vls_mt_mq_lock ();
+	  *locks_acq |= VLS_MT_LOCK_MQ;
+	}
+      break;
+    case VLS_MT_OP_WRITE:
+      ASSERT (s);
+      if (!is_nonblk)
+	is_nonblk = vcl_session_write_ready (s) != 0;
+      if (!is_nonblk)
+	{
+	  vls_mt_mq_lock ();
+	  *locks_acq |= VLS_MT_LOCK_MQ;
+	}
+      break;
+    case VLS_MT_OP_XPOLL:
+      vls_mt_mq_lock ();
+      *locks_acq |= VLS_MT_LOCK_MQ;
+      break;
+    case VLS_MT_OP_SPOOL:
+      vls_mt_spool_lock ();
+      *locks_acq |= VLS_MT_LOCK_SPOOL;
+      break;
+    default:
+      break;
+    }
+}
+
+static void
+vls_mt_rel_locks (int locks_acq)
+{
+  if (locks_acq & VLS_MT_LOCK_MQ)
+    vls_mt_mq_unlock ();
+  if (locks_acq & VLS_MT_LOCK_SPOOL)
+    vls_mt_create_unlock ();
+}
+
+#define vls_mt_guard(_vls, _op)				\
+  int _locks_acq = 0;					\
+  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))	\
+    vls_mt_add ();					\
+  if (PREDICT_FALSE (vlsl->vls_mt_n_threads > 1))	\
+    vls_mt_acq_locks (_vls, _op, &_locks_acq);		\
+
+#define vls_mt_unguard()				\
+  if (PREDICT_FALSE (_locks_acq))			\
+    vls_mt_rel_locks (_locks_acq)
+
 int
 vls_write (vls_handle_t vlsh, void *buf, size_t nbytes)
 {
@@ -253,7 +485,10 @@ vls_write (vls_handle_t vlsh, void *buf, size_t nbytes)
 
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
+
+  vls_mt_guard (vls, VLS_MT_OP_WRITE);
   rv = vppcom_session_write (vls_to_sh_tu (vls), buf, nbytes);
+  vls_mt_unguard ();
   vls_get_and_unlock (vlsh);
   return rv;
 }
@@ -266,7 +501,9 @@ vls_write_msg (vls_handle_t vlsh, void *buf, size_t nbytes)
 
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
+  vls_mt_guard (vls, VLS_MT_OP_WRITE);
   rv = vppcom_session_write_msg (vls_to_sh_tu (vls), buf, nbytes);
+  vls_mt_unguard ();
   vls_get_and_unlock (vlsh);
   return rv;
 }
@@ -280,7 +517,9 @@ vls_sendto (vls_handle_t vlsh, void *buf, int buflen, int flags,
 
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
+  vls_mt_guard (vls, VLS_MT_OP_WRITE);
   rv = vppcom_session_sendto (vls_to_sh_tu (vls), buf, buflen, flags, ep);
+  vls_mt_unguard ();
   vls_get_and_unlock (vlsh);
   return rv;
 }
@@ -293,7 +532,9 @@ vls_read (vls_handle_t vlsh, void *buf, size_t nbytes)
 
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
+  vls_mt_guard (vls, VLS_MT_OP_READ);
   rv = vppcom_session_read (vls_to_sh_tu (vls), buf, nbytes);
+  vls_mt_unguard ();
   vls_get_and_unlock (vlsh);
   return rv;
 }
@@ -307,8 +548,10 @@ vls_recvfrom (vls_handle_t vlsh, void *buffer, uint32_t buflen, int flags,
 
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
+  vls_mt_guard (vls, VLS_MT_OP_READ);
   rv = vppcom_session_recvfrom (vls_to_sh_tu (vls), buffer, buflen, flags,
 				ep);
+  vls_mt_unguard ();
   vls_get_and_unlock (vlsh);
   return rv;
 }
@@ -319,6 +562,9 @@ vls_attr (vls_handle_t vlsh, uint32_t op, void *buffer, uint32_t * buflen)
   vcl_locked_session_t *vls;
   int rv;
 
+  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))
+    vls_mt_add ();
+
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
   rv = vppcom_session_attr (vls_to_sh_tu (vls), op, buffer, buflen);
@@ -347,7 +593,9 @@ vls_listen (vls_handle_t vlsh, int q_len)
 
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
+  vls_mt_guard (vls, VLS_MT_OP_XPOLL);
   rv = vppcom_session_listen (vls_to_sh_tu (vls), q_len);
+  vls_mt_unguard ();
   vls_get_and_unlock (vlsh);
   return rv;
 }
@@ -360,11 +608,53 @@ vls_connect (vls_handle_t vlsh, vppcom_endpt_t * server_ep)
 
   if (!(vls = vls_get_w_dlock (vlsh)))
     return VPPCOM_EBADFD;
+  vls_mt_guard (vls, VLS_MT_OP_XPOLL);
   rv = vppcom_session_connect (vls_to_sh_tu (vls), server_ep);
+  vls_mt_unguard ();
   vls_get_and_unlock (vlsh);
   return rv;
 }
 
+static inline void
+vls_mp_checks (vcl_locked_session_t * vls, int is_add)
+{
+  vcl_worker_t *wrk = vcl_worker_get_current ();
+  vcl_session_t *s;
+
+  s = vcl_session_get (wrk, vls->session_index);
+  switch (s->session_state)
+    {
+    case STATE_LISTEN:
+      if (is_add)
+	{
+	  if (vls->worker_index == wrk->wrk_index)
+	    vls_listener_wrk_set (vls, wrk->wrk_index, 1 /* is_active */ );
+	  break;
+	}
+      vls_listener_wrk_stop_listen (vls, vls->worker_index);
+      break;
+    case STATE_LISTEN_NO_MQ:
+      if (!is_add)
+	break;
+
+      /* Register worker as listener */
+      vls_listener_wrk_start_listen (vls, wrk->wrk_index);
+
+      /* If owner worker did not attempt to accept/xpoll on the session,
+       * force a listen stop for it, since it may not be interested in
+       * accepting new sessions.
+       * This is pretty much a hack done to give app workers the illusion
+       * that it is fine to listen and not accept new sessions for a
+       * given listener. Without it, we would accumulate unhandled
+       * accepts on the passive worker message queue. */
+      if (!vls_listener_wrk_is_active (vls, vls->worker_index))
+	vls_listener_wrk_stop_listen (vls, vls->worker_index);
+      break;
+    default:
+      break;
+    }
+}
+
 vls_handle_t
 vls_accept (vls_handle_t listener_vlsh, vppcom_endpt_t * ep, int flags)
 {
@@ -374,7 +664,11 @@ vls_accept (vls_handle_t listener_vlsh, vppcom_endpt_t * ep, int flags)
 
   if (!(vls = vls_get_w_dlock (listener_vlsh)))
     return VPPCOM_EBADFD;
+  if (vcl_n_workers () > 1)
+    vls_mp_checks (vls, 1 /* is_add */ );
+  vls_mt_guard (vls, VLS_MT_OP_SPOOL);
   sh = vppcom_session_accept (vls_to_sh_tu (vls), ep, flags);
+  vls_mt_unguard ();
   vls_get_and_unlock (listener_vlsh);
   if (sh < 0)
     return sh;
@@ -390,7 +684,9 @@ vls_create (uint8_t proto, uint8_t is_nonblocking)
   vcl_session_handle_t sh;
   vls_handle_t vlsh;
 
+  vls_mt_guard (0, VLS_MT_OP_SPOOL);
   sh = vppcom_session_create (proto, is_nonblocking);
+  vls_mt_unguard ();
   if (sh == INVALID_SESSION_ID)
     return VLS_INVALID_HANDLE;
 
@@ -405,28 +701,34 @@ int
 vls_close (vls_handle_t vlsh)
 {
   vcl_locked_session_t *vls;
-  vcl_session_handle_t sh;
   int rv;
 
-  if (!(vls = vls_get_w_dlock (vlsh)))
-    return VPPCOM_EBADFD;
+  vls_table_wlock ();
 
-  if (vls_is_shared (vls))
+  vls = vls_get_and_lock (vlsh);
+  if (!vls)
     {
-      vls_unshare_session (vls);
-      vls_dunlock (vls);
-      return VPPCOM_OK;
+      vls_table_wunlock ();
+      return VPPCOM_EBADFD;
     }
 
-  sh = vls_to_sh (vls);
-  if ((rv = vppcom_session_close (sh)))
+  vls_mt_guard (0, VLS_MT_OP_SPOOL);
+  if (vls_is_shared (vls))
     {
-      vls_dunlock (vls);
-      return rv;
+      /* At least two workers share the session so vls won't be freed */
+      vls_unshare_session (vls, vcl_worker_get_current ());
+      vls_unlock (vls);
+      vls_mt_unguard ();
+      vls_table_wunlock ();
+      return VPPCOM_OK;
     }
 
-  vls_dunlock (vls);
-  vls_get_and_free (vlsh);
+  rv = vppcom_session_close (vls_to_sh (vls));
+  vls_free (vls);
+  vls_mt_unguard ();
+
+  vls_table_wunlock ();
+
   return rv;
 }
 
@@ -436,6 +738,9 @@ vls_epoll_create (void)
   vcl_session_handle_t sh;
   vls_handle_t vlsh;
 
+  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))
+    vls_mt_add ();
+
   sh = vppcom_epoll_create ();
   if (sh == INVALID_SESSION_ID)
     return VLS_INVALID_HANDLE;
@@ -447,6 +752,22 @@ vls_epoll_create (void)
   return vlsh;
 }
 
+static void
+vls_epoll_ctl_mp_checks (vcl_locked_session_t * vls, int op)
+{
+  if (vcl_n_workers () <= 1)
+    {
+      vlsl->epoll_mp_check = 1;
+      return;
+    }
+
+  if (op == EPOLL_CTL_MOD)
+    return;
+
+  vlsl->epoll_mp_check = 1;
+  vls_mp_checks (vls, op == EPOLL_CTL_ADD);
+}
+
 int
 vls_epoll_ctl (vls_handle_t ep_vlsh, int op, vls_handle_t vlsh,
 	       struct epoll_event *event)
@@ -460,6 +781,10 @@ vls_epoll_ctl (vls_handle_t ep_vlsh, int op, vls_handle_t vlsh,
   vls = vls_get_and_lock (vlsh);
   ep_sh = vls_to_sh (ep_vls);
   sh = vls_to_sh (vls);
+
+  if (PREDICT_FALSE (!vlsl->epoll_mp_check))
+    vls_epoll_ctl_mp_checks (vls, op);
+
   vls_table_runlock ();
 
   rv = vppcom_epoll_ctl (ep_sh, op, sh, event);
@@ -482,46 +807,92 @@ vls_epoll_wait (vls_handle_t ep_vlsh, struct epoll_event *events,
 
   if (!(vls = vls_get_w_dlock (ep_vlsh)))
     return VPPCOM_EBADFD;
+  vls_mt_guard (0, VLS_MT_OP_XPOLL);
   rv = vppcom_epoll_wait (vls_to_sh_tu (vls), events, maxevents,
 			  wait_for_time);
+  vls_mt_unguard ();
   vls_get_and_unlock (ep_vlsh);
   return rv;
 }
 
-vcl_session_handle_t
-vlsh_to_sh (vls_handle_t vlsh)
+static void
+vls_select_mp_checks (vcl_si_set * read_map)
 {
   vcl_locked_session_t *vls;
-  int rv;
+  vcl_worker_t *wrk;
+  vcl_session_t *s;
+  u32 si;
 
-  vls = vls_get_w_dlock (vlsh);
-  if (!vls)
-    return INVALID_SESSION_ID;
-  rv = vls_to_sh (vls);
-  vls_dunlock (vls);
-  return rv;
+  if (vcl_n_workers () <= 1)
+    {
+      vlsl->select_mp_check = 1;
+      return;
+    }
+
+  if (!read_map)
+    return;
+
+  vlsl->select_mp_check = 1;
+  wrk = vcl_worker_get_current ();
+
+  /* *INDENT-OFF* */
+  clib_bitmap_foreach (si, read_map, ({
+    s = vcl_session_get (wrk, si);
+    if (s->session_state == STATE_LISTEN)
+      {
+	vls = vls_get (vls_session_index_to_vlsh (si));
+	vls_mp_checks (vls, 1 /* is_add */);
+      }
+  }));
+  /* *INDENT-ON* */
 }
 
-vcl_session_handle_t
-vlsh_to_session_index (vls_handle_t vlsh)
+int
+vls_select (int n_bits, vcl_si_set * read_map, vcl_si_set * write_map,
+	    vcl_si_set * except_map, double wait_for_time)
 {
-  vcl_session_handle_t sh;
-  sh = vlsh_to_sh (vlsh);
-  return vppcom_session_index (sh);
+  int rv;
+
+  vls_mt_guard (0, VLS_MT_OP_XPOLL);
+  if (PREDICT_FALSE (!vlsl->select_mp_check))
+    vls_select_mp_checks (read_map);
+  rv = vppcom_select (n_bits, read_map, write_map, except_map, wait_for_time);
+  vls_mt_unguard ();
+  return rv;
 }
 
-vls_handle_t
-vls_session_index_to_vlsh (uint32_t session_index)
+static void
+vls_unshare_vcl_worker_sessions (vcl_worker_t * wrk)
 {
-  vls_handle_t vlsh;
-  uword *vlshp;
+  u32 current_wrk, is_current;
+  vcl_locked_session_t *vls;
+  vcl_session_t *s;
 
-  vls_table_rlock ();
-  vlshp = hash_get (vlsm->session_index_to_vlsh_table, session_index);
-  vlsh = vlshp ? *vlshp : VLS_INVALID_HANDLE;
-  vls_table_runlock ();
+  if (pool_elts (vcm->workers) <= 1)
+    return;
 
-  return vlsh;
+  current_wrk = vcl_get_worker_index ();
+  is_current = current_wrk == wrk->wrk_index;
+  vls_table_wlock ();
+
+  /* *INDENT-OFF* */
+  pool_foreach (s, wrk->sessions, ({
+    vls = vls_get (vls_si_to_vlsh (s->session_index));
+    if (vls && (is_current || vls_is_shared_by_wrk (vls, current_wrk)))
+      vls_unshare_session (vls, wrk);
+  }));
+  /* *INDENT-ON* */
+
+  vls_table_wunlock ();
+}
+
+static void
+vls_cleanup_vcl_worker (vcl_worker_t * wrk)
+{
+  /* Unshare sessions and also cleanup worker since child may have
+   * called _exit () and therefore vcl may not catch the event */
+  vls_unshare_vcl_worker_sessions (wrk);
+  vcl_worker_cleanup (wrk, 1 /* notify vpp */ );
 }
 
 static void
@@ -542,8 +913,8 @@ vls_cleanup_forked_child (vcl_worker_t * wrk, vcl_worker_t * child_wrk)
 	    vls_cleanup_forked_child (child_wrk, sub_child);
 	}
     }
-  vcl_worker_cleanup (child_wrk, 1 /* notify vpp */ );
-  VDBG (0, "Cleaned up wrk %u", child_wrk->wrk_index);
+  vls_cleanup_vcl_worker (child_wrk);
+  VDBG (0, "Cleaned up forked child wrk %u", child_wrk->wrk_index);
   wrk->forked_child = ~0;
 }
 
@@ -654,6 +1025,13 @@ vls_app_fork_child_handler (void)
   vls_worker_copy_on_fork (parent_wrk);
   parent_wrk->forked_child = vcl_get_worker_index ();
 
+  /* Reset number of threads and set wrk index */
+  vlsl->vls_mt_n_threads = 0;
+  vlsl->vls_wrk_index = vcl_get_worker_index ();
+  vlsl->select_mp_check = 0;
+  vlsl->epoll_mp_check = 0;
+  vls_mt_locks_init ();
+
   VDBG (0, "forked child main worker initialized");
   vcm->forking = 0;
 }
@@ -666,15 +1044,28 @@ vls_app_fork_parent_handler (void)
     ;
 }
 
+void
+vls_app_exit (void)
+{
+  /* Unshare the sessions. VCL will clean up the worker */
+  vls_unshare_vcl_worker_sessions (vcl_worker_get_current ());
+}
+
 int
 vls_app_create (char *app_name)
 {
   int rv;
+
   if ((rv = vppcom_app_create (app_name)))
     return rv;
+  vlsm = clib_mem_alloc (sizeof (vls_main_t));
+  clib_memset (vlsm, 0, sizeof (*vlsm));
   clib_rwlock_init (&vlsm->vls_table_lock);
   pthread_atfork (vls_app_pre_fork, vls_app_fork_parent_handler,
 		  vls_app_fork_child_handler);
+  atexit (vls_app_exit);
+  vlsl->vls_wrk_index = vcl_get_worker_index ();
+  vls_mt_locks_init ();
   return VPPCOM_OK;
 }