vcl/ldp: select cleanup/improvements

Change-Id: I640e69388f2ab0f66ad60c5165c749f5a5a9f525
Signed-off-by: Florin Coras <fcoras@cisco.com>

4 files changed, 223 insertions, 254 deletions

diff --git a/src/vcl/ldp.c b/src/vcl/ldp.c
index 1c038b0a102..9f195c64a1b 100644
--- a/src/vcl/ldp.c
+++ b/src/vcl/ldp.c
@@ -62,13 +62,12 @@ typedef struct ldp_worker_ctx_
   clib_bitmap_t *rd_bitmap;
   clib_bitmap_t *wr_bitmap;
   clib_bitmap_t *ex_bitmap;
-  clib_bitmap_t *sid_rd_bitmap;
-  clib_bitmap_t *sid_wr_bitmap;
-  clib_bitmap_t *sid_ex_bitmap;
+  clib_bitmap_t *si_rd_bitmap;
+  clib_bitmap_t *si_wr_bitmap;
+  clib_bitmap_t *si_ex_bitmap;
   clib_bitmap_t *libc_rd_bitmap;
   clib_bitmap_t *libc_wr_bitmap;
   clib_bitmap_t *libc_ex_bitmap;
-  u8 select_vcl;
 
   /*
    * Poll state
@@ -85,6 +84,13 @@ typedef struct ldp_worker_ctx_
 
 } ldp_worker_ctx_t;
 
+/* clib_bitmap_t, fd_mask and vcl_si_set are used interchangeably. Make sure
+ * they are the same size */
+STATIC_ASSERT (sizeof (clib_bitmap_t) == sizeof (fd_mask),
+	       "ldp bitmap size mismatch");
+STATIC_ASSERT (sizeof (vcl_si_set) == sizeof (fd_mask),
+	       "ldp bitmap size mismatch");
+
 typedef struct
 {
   ldp_worker_ctx_t *workers;
@@ -211,32 +217,29 @@ ldp_init (void)
       u32 sb;
       if (sscanf (env_var_str, "%u", &sb) != 1)
 	{
-	  clib_warning ("LDP<%d>: WARNING: Invalid LDP sid bit specified in"
-			" the env var " LDP_ENV_SID_BIT " (%s)! sid bit "
-			"value %d (0x%x)", getpid (), env_var_str,
-			ldp->vlsh_bit_val, ldp->vlsh_bit_val);
+	  LDBG (0, "WARNING: Invalid LDP sid bit specified in the env var "
+		LDP_ENV_SID_BIT " (%s)! sid bit value %d (0x%x)", env_var_str,
+		ldp->vlsh_bit_val, ldp->vlsh_bit_val);
 	}
       else if (sb < LDP_SID_BIT_MIN)
 	{
 	  ldp->vlsh_bit_val = (1 << LDP_SID_BIT_MIN);
 	  ldp->vlsh_bit_mask = ldp->vlsh_bit_val - 1;
 
-	  clib_warning ("LDP<%d>: WARNING: LDP sid bit (%u) specified in the"
-			" env var " LDP_ENV_SID_BIT " (%s) is too small. "
-			"Using LDP_SID_BIT_MIN (%d)! sid bit value %d (0x%x)",
-			getpid (), sb, env_var_str, LDP_SID_BIT_MIN,
-			ldp->vlsh_bit_val, ldp->vlsh_bit_val);
+	  LDBG (0, "WARNING: LDP sid bit (%u) specified in the env var "
+		LDP_ENV_SID_BIT " (%s) is too small. Using LDP_SID_BIT_MIN"
+		" (%d)! sid bit value %d (0x%x)", sb, env_var_str,
+		LDP_SID_BIT_MIN, ldp->vlsh_bit_val, ldp->vlsh_bit_val);
 	}
       else if (sb > LDP_SID_BIT_MAX)
 	{
 	  ldp->vlsh_bit_val = (1 << LDP_SID_BIT_MAX);
 	  ldp->vlsh_bit_mask = ldp->vlsh_bit_val - 1;
 
-	  clib_warning ("LDP<%d>: WARNING: LDP sid bit (%u) specified in the"
-			" env var " LDP_ENV_SID_BIT " (%s) is too big. Using"
-			" LDP_SID_BIT_MAX (%d)! sid bit value %d (0x%x)",
-			getpid (), sb, env_var_str, LDP_SID_BIT_MAX,
-			ldp->vlsh_bit_val, ldp->vlsh_bit_val);
+	  LDBG (0, "WARNING: LDP sid bit (%u) specified in the env var "
+		LDP_ENV_SID_BIT " (%s) is too big. Using LDP_SID_BIT_MAX"
+		" (%d)! sid bit value %d (0x%x)", sb, env_var_str,
+		LDP_SID_BIT_MAX, ldp->vlsh_bit_val, ldp->vlsh_bit_val);
 	}
       else
 	{
@@ -247,6 +250,15 @@ ldp_init (void)
 		LDP_ENV_SID_BIT "!  sid bit value %d (0x%x)", sb,
 		ldp->vlsh_bit_val, ldp->vlsh_bit_val);
 	}
+
+      /* Make sure there are enough bits in the fd set for vcl sessions */
+      if (ldp->vlsh_bit_val > FD_SETSIZE / 2)
+	{
+	  LDBG (0, "ERROR: LDP vlsh bit value %d > FD_SETSIZE/2 %d!",
+		ldp->vlsh_bit_val, FD_SETSIZE / 2);
+	  ldp->init = 0;
+	  return -1;
+	}
     }
 
   clib_time_init (&ldpw->clib_time);
@@ -563,6 +575,79 @@ ioctl (int fd, unsigned long int cmd, ...)
   return rv;
 }
 
+always_inline void
+ldp_select_init_maps (fd_set * __restrict original,
+		      clib_bitmap_t ** resultb, clib_bitmap_t ** libcb,
+		      clib_bitmap_t ** vclb, int nfds, u32 minbits,
+		      u32 n_bytes, uword * si_bits, uword * libc_bits)
+{
+  uword si_bits_set, libc_bits_set;
+  vls_handle_t vlsh;
+  int fd;
+
+  clib_bitmap_validate (*vclb, minbits);
+  clib_bitmap_validate (*libcb, minbits);
+  clib_bitmap_validate (*resultb, minbits);
+  clib_memcpy_fast (*resultb, original, n_bytes);
+  memset (original, 0, n_bytes);
+
+  /* *INDENT-OFF* */
+  clib_bitmap_foreach (fd, *resultb, ({
+    if (fd > nfds)
+      break;
+    vlsh = ldp_fd_to_vlsh (fd);
+    if (vlsh == VLS_INVALID_HANDLE)
+      clib_bitmap_set_no_check (*libcb, fd, 1);
+    else
+      clib_bitmap_set_no_check (*vclb, vlsh_to_session_index (vlsh), 1);
+  }));
+  /* *INDENT-ON* */
+
+  si_bits_set = clib_bitmap_last_set (*vclb) + 1;
+  *si_bits = (si_bits_set > *si_bits) ? si_bits_set : *si_bits;
+
+  libc_bits_set = clib_bitmap_last_set (*libcb) + 1;
+  *libc_bits = (libc_bits_set > *libc_bits) ? libc_bits_set : *libc_bits;
+}
+
+always_inline int
+ldp_select_vcl_map_to_libc (clib_bitmap_t * vclb, fd_set * __restrict libcb)
+{
+  vls_handle_t vlsh;
+  uword si;
+  int fd;
+
+  if (!libcb)
+    return 0;
+
+  /* *INDENT-OFF* */
+  clib_bitmap_foreach (si, vclb, ({
+    vlsh = vls_session_index_to_vlsh (si);
+    fd = ldp_vlsh_to_fd (vlsh);
+    if (PREDICT_FALSE (fd < 0))
+      {
+        errno = EBADFD;
+        return -1;
+      }
+    FD_SET (fd, libcb);
+  }));
+  /* *INDENT-ON* */
+
+  return 0;
+}
+
+always_inline void
+ldp_select_libc_map_merge (clib_bitmap_t * result, fd_set * __restrict libcb)
+{
+  uword fd;
+
+  /* *INDENT-OFF* */
+  clib_bitmap_foreach (fd, result, ({
+    FD_SET ((int)fd, libcb);
+  }));
+  /* *INDENT-ON* */
+}
+
 int
 ldp_pselect (int nfds, fd_set * __restrict readfds,
 	     fd_set * __restrict writefds,
@@ -570,12 +655,12 @@ ldp_pselect (int nfds, fd_set * __restrict readfds,
 	     const struct timespec *__restrict timeout,
 	     const __sigset_t * __restrict sigmask)
 {
-  uword sid_bits, sid_bits_set, libc_bits, libc_bits_set;
+  u32 minbits = clib_max (nfds, BITS (uword)), n_bytes;
   ldp_worker_ctx_t *ldpw = ldp_worker_get_current ();
-  u32 minbits = clib_max (nfds, BITS (uword)), si;
-  vls_handle_t vlsh;
-  f64 time_out;
-  int rv, fd;
+  struct timespec libc_tspec = { 0 };
+  f64 time_out, vcl_timeout = 0;
+  uword si_bits, libc_bits;
+  int rv, bits_set = 0;
 
   if (nfds < 0)
     {
@@ -605,7 +690,6 @@ ldp_pselect (int nfds, fd_set * __restrict readfds,
   else
     time_out = -1;
 
-
   if (nfds <= ldp->vlsh_bit_val)
     {
       rv = libc_pselect (nfds, readfds, writefds, exceptfds,
@@ -613,218 +697,112 @@ ldp_pselect (int nfds, fd_set * __restrict readfds,
       goto done;
     }
 
-  if (PREDICT_FALSE (ldp->vlsh_bit_val > FD_SETSIZE / 2))
-    {
-      LDBG (0, "ERROR: LDP sid bit value %d > FD_SETSIZE/2 %d!",
-	    ldp->vlsh_bit_val, FD_SETSIZE / 2);
-      errno = EOVERFLOW;
-      return -1;
-    }
-
-  sid_bits = libc_bits = 0;
-  u32 n_bytes = nfds / 8 + ((nfds % 8) ? 1 : 0);
+  si_bits = libc_bits = 0;
+  n_bytes = nfds / 8 + ((nfds % 8) ? 1 : 0);
 
   if (readfds)
-    {
-      clib_bitmap_validate (ldpw->sid_rd_bitmap, minbits);
-      clib_bitmap_validate (ldpw->libc_rd_bitmap, minbits);
-      clib_bitmap_validate (ldpw->rd_bitmap, minbits);
-      clib_memcpy_fast (ldpw->rd_bitmap, readfds, n_bytes);
-      memset (readfds, 0, n_bytes);
-
-      /* *INDENT-OFF* */
-      clib_bitmap_foreach (fd, ldpw->rd_bitmap, ({
-	if (fd > nfds)
-	  break;
-        vlsh = ldp_fd_to_vlsh (fd);
-        if (vlsh == VLS_INVALID_HANDLE)
-          clib_bitmap_set_no_check (ldpw->libc_rd_bitmap, fd, 1);
-        else
-          clib_bitmap_set_no_check (ldpw->sid_rd_bitmap,
-                                    vlsh_to_session_index (vlsh), 1);
-      }));
-      /* *INDENT-ON* */
-
-      sid_bits_set = clib_bitmap_last_set (ldpw->sid_rd_bitmap) + 1;
-      sid_bits = (sid_bits_set > sid_bits) ? sid_bits_set : sid_bits;
-
-      libc_bits_set = clib_bitmap_last_set (ldpw->libc_rd_bitmap) + 1;
-      libc_bits = (libc_bits_set > libc_bits) ? libc_bits_set : libc_bits;
-    }
+    ldp_select_init_maps (readfds, &ldpw->rd_bitmap, &ldpw->libc_rd_bitmap,
+			  &ldpw->si_rd_bitmap, nfds, minbits, n_bytes,
+			  &si_bits, &libc_bits);
   if (writefds)
-    {
-      clib_bitmap_validate (ldpw->sid_wr_bitmap, minbits);
-      clib_bitmap_validate (ldpw->libc_wr_bitmap, minbits);
-      clib_bitmap_validate (ldpw->wr_bitmap, minbits);
-      clib_memcpy_fast (ldpw->wr_bitmap, writefds, n_bytes);
-      memset (writefds, 0, n_bytes);
-
-      /* *INDENT-OFF* */
-      clib_bitmap_foreach (fd, ldpw->wr_bitmap, ({
-	if (fd > nfds)
-	  break;
-        vlsh = ldp_fd_to_vlsh (fd);
-        if (vlsh == VLS_INVALID_HANDLE)
-          clib_bitmap_set_no_check (ldpw->libc_wr_bitmap, fd, 1);
-        else
-          clib_bitmap_set_no_check (ldpw->sid_wr_bitmap,
-                                    vlsh_to_session_index (vlsh), 1);
-      }));
-      /* *INDENT-ON* */
-
-      sid_bits_set = clib_bitmap_last_set (ldpw->sid_wr_bitmap) + 1;
-      sid_bits = (sid_bits_set > sid_bits) ? sid_bits_set : sid_bits;
-
-      libc_bits_set = clib_bitmap_last_set (ldpw->libc_wr_bitmap) + 1;
-      libc_bits = (libc_bits_set > libc_bits) ? libc_bits_set : libc_bits;
-
-    }
+    ldp_select_init_maps (writefds, &ldpw->wr_bitmap,
+			  &ldpw->libc_wr_bitmap, &ldpw->si_wr_bitmap, nfds,
+			  minbits, n_bytes, &si_bits, &libc_bits);
   if (exceptfds)
-    {
-      clib_bitmap_validate (ldpw->sid_ex_bitmap, minbits);
-      clib_bitmap_validate (ldpw->libc_ex_bitmap, minbits);
-      clib_bitmap_validate (ldpw->ex_bitmap, minbits);
-      clib_memcpy_fast (ldpw->ex_bitmap, exceptfds, n_bytes);
-      memset (exceptfds, 0, n_bytes);
-
-      /* *INDENT-OFF* */
-      clib_bitmap_foreach (fd, ldpw->ex_bitmap, ({
-	if (fd > nfds)
-	  break;
-        vlsh = ldp_fd_to_vlsh (fd);
-        if (vlsh == VLS_INVALID_HANDLE)
-          clib_bitmap_set_no_check (ldpw->libc_ex_bitmap, fd, 1);
-        else
-          clib_bitmap_set_no_check (ldpw->sid_ex_bitmap,
-                                    vlsh_to_session_index (vlsh), 1);
-      }));
-      /* *INDENT-ON* */
-
-      sid_bits_set = clib_bitmap_last_set (ldpw->sid_ex_bitmap) + 1;
-      sid_bits = (sid_bits_set > sid_bits) ? sid_bits_set : sid_bits;
-
-      libc_bits_set = clib_bitmap_last_set (ldpw->libc_ex_bitmap) + 1;
-      libc_bits = (libc_bits_set > libc_bits) ? libc_bits_set : libc_bits;
-    }
+    ldp_select_init_maps (exceptfds, &ldpw->ex_bitmap,
+			  &ldpw->libc_ex_bitmap, &ldpw->si_ex_bitmap, nfds,
+			  minbits, n_bytes, &si_bits, &libc_bits);
 
-  if (PREDICT_FALSE (!sid_bits && !libc_bits))
+  if (PREDICT_FALSE (!si_bits && !libc_bits))
     {
       errno = EINVAL;
       rv = -1;
       goto done;
     }
 
+  libc_tspec = si_bits ? libc_tspec : *timeout;
+
   do
     {
-      if (sid_bits)
+      if (si_bits)
 	{
-	  if (!ldpw->select_vcl)
+	  if (readfds)
+	    clib_memcpy_fast (ldpw->rd_bitmap, ldpw->si_rd_bitmap,
+			      vec_len (ldpw->rd_bitmap) *
+			      sizeof (clib_bitmap_t));
+	  if (writefds)
+	    clib_memcpy_fast (ldpw->wr_bitmap, ldpw->si_wr_bitmap,
+			      vec_len (ldpw->wr_bitmap) *
+			      sizeof (clib_bitmap_t));
+	  if (exceptfds)
+	    clib_memcpy_fast (ldpw->ex_bitmap, ldpw->si_ex_bitmap,
+			      vec_len (ldpw->ex_bitmap) *
+			      sizeof (clib_bitmap_t));
+
+	  rv = vppcom_select (si_bits, readfds ? ldpw->rd_bitmap : NULL,
+			      writefds ? ldpw->wr_bitmap : NULL,
+			      exceptfds ? ldpw->ex_bitmap : NULL,
+			      vcl_timeout);
+	  if (rv < 0)
 	    {
-	      if (readfds)
-		clib_memcpy_fast (ldpw->rd_bitmap, ldpw->sid_rd_bitmap,
-				  vec_len (ldpw->rd_bitmap) *
-				  sizeof (clib_bitmap_t));
-	      if (writefds)
-		clib_memcpy_fast (ldpw->wr_bitmap, ldpw->sid_wr_bitmap,
-				  vec_len (ldpw->wr_bitmap) *
-				  sizeof (clib_bitmap_t));
-	      if (exceptfds)
-		clib_memcpy_fast (ldpw->ex_bitmap, ldpw->sid_ex_bitmap,
-				  vec_len (ldpw->ex_bitmap) *
-				  sizeof (clib_bitmap_t));
-
-	      rv = vppcom_select (sid_bits,
-				  readfds ? (unsigned long *) ldpw->rd_bitmap
-				  : NULL,
-				  writefds ? (unsigned long *) ldpw->wr_bitmap
-				  : NULL,
-				  exceptfds ? (unsigned long *)
-				  ldpw->ex_bitmap : NULL, 0);
-	      if (rv < 0)
+	      errno = -rv;
+	      rv = -1;
+	    }
+	  else if (rv > 0)
+	    {
+	      if (ldp_select_vcl_map_to_libc (ldpw->rd_bitmap, readfds))
 		{
-		  errno = -rv;
 		  rv = -1;
+		  goto done;
 		}
-	      else if (rv > 0)
+
+	      if (ldp_select_vcl_map_to_libc (ldpw->wr_bitmap, writefds))
 		{
-		  if (readfds)
-		    {
-                      /* *INDENT-OFF* */
-                      clib_bitmap_foreach (si, ldpw->rd_bitmap, ({
-                	vlsh = vls_session_index_to_vlsh (si);
-                        fd = ldp_vlsh_to_fd (vlsh);
-                        if (PREDICT_FALSE (fd < 0))
-                          {
-                            errno = EBADFD;
-                            rv = -1;
-                            goto done;
-                          }
-                        FD_SET (fd, readfds);
-                      }));
-                      /* *INDENT-ON* */
-		    }
-		  if (writefds)
-		    {
-                      /* *INDENT-OFF* */
-                      clib_bitmap_foreach (si, ldpw->wr_bitmap, ({
-                	vlsh = vls_session_index_to_vlsh (si);
-                        fd = ldp_vlsh_to_fd (vlsh);
-                        if (PREDICT_FALSE (fd < 0))
-                          {
-                            errno = EBADFD;
-                            rv = -1;
-                            goto done;
-                          }
-                        FD_SET (fd, writefds);
-                      }));
-                      /* *INDENT-ON* */
-		    }
-		  if (exceptfds)
-		    {
-                      /* *INDENT-OFF* */
-                      clib_bitmap_foreach (si, ldpw->ex_bitmap, ({
-                	vlsh = vls_session_index_to_vlsh (si);
-                        fd = ldp_vlsh_to_fd (vlsh);
-                        if (PREDICT_FALSE (fd < 0))
-                          {
-                            errno = EBADFD;
-                            rv = -1;
-                            goto done;
-                          }
-                        FD_SET (fd, exceptfds);
-                      }));
-                      /* *INDENT-ON* */
-		    }
-		  ldpw->select_vcl = 1;
+		  rv = -1;
+		  goto done;
+		}
+
+	      if (ldp_select_vcl_map_to_libc (ldpw->ex_bitmap, exceptfds))
+		{
+		  rv = -1;
 		  goto done;
 		}
+	      bits_set = rv;
 	    }
-	  else
-	    ldpw->select_vcl = 0;
 	}
       if (libc_bits)
 	{
-	  struct timespec tspec;
-
 	  if (readfds)
-	    clib_memcpy_fast (readfds, ldpw->libc_rd_bitmap,
-			      vec_len (ldpw->rd_bitmap) *
+	    clib_memcpy_fast (ldpw->rd_bitmap, ldpw->libc_rd_bitmap,
+			      vec_len (ldpw->libc_rd_bitmap) *
 			      sizeof (clib_bitmap_t));
 	  if (writefds)
-	    clib_memcpy_fast (writefds, ldpw->libc_wr_bitmap,
-			      vec_len (ldpw->wr_bitmap) *
+	    clib_memcpy_fast (ldpw->wr_bitmap, ldpw->libc_wr_bitmap,
+			      vec_len (ldpw->libc_wr_bitmap) *
 			      sizeof (clib_bitmap_t));
 	  if (exceptfds)
-	    clib_memcpy_fast (exceptfds, ldpw->libc_ex_bitmap,
-			      vec_len (ldpw->ex_bitmap) *
+	    clib_memcpy_fast (ldpw->ex_bitmap, ldpw->libc_ex_bitmap,
+			      vec_len (ldpw->libc_ex_bitmap) *
 			      sizeof (clib_bitmap_t));
-	  tspec.tv_sec = tspec.tv_nsec = 0;
+
 	  rv = libc_pselect (libc_bits,
-			     readfds ? readfds : NULL,
-			     writefds ? writefds : NULL,
-			     exceptfds ? exceptfds : NULL, &tspec, sigmask);
-	  if (rv != 0)
-	    goto done;
+			     readfds ? (fd_set *) ldpw->rd_bitmap : NULL,
+			     writefds ? (fd_set *) ldpw->wr_bitmap : NULL,
+			     exceptfds ? (fd_set *) ldpw->ex_bitmap : NULL,
+			     &libc_tspec, sigmask);
+	  if (rv > 0)
+	    {
+	      ldp_select_libc_map_merge (ldpw->rd_bitmap, readfds);
+	      ldp_select_libc_map_merge (ldpw->wr_bitmap, writefds);
+	      ldp_select_libc_map_merge (ldpw->ex_bitmap, exceptfds);
+	      bits_set += rv;
+	    }
+	}
+
+      if (bits_set)
+	{
+	  rv = bits_set;
+	  goto done;
 	}
     }
   while ((time_out == -1) || (clib_time_now (&ldpw->clib_time) < time_out));
@@ -833,13 +811,13 @@ ldp_pselect (int nfds, fd_set * __restrict readfds,
 done:
   /* TBD: set timeout to amount of time left */
   clib_bitmap_zero (ldpw->rd_bitmap);
-  clib_bitmap_zero (ldpw->sid_rd_bitmap);
+  clib_bitmap_zero (ldpw->si_rd_bitmap);
   clib_bitmap_zero (ldpw->libc_rd_bitmap);
   clib_bitmap_zero (ldpw->wr_bitmap);
-  clib_bitmap_zero (ldpw->sid_wr_bitmap);
+  clib_bitmap_zero (ldpw->si_wr_bitmap);
   clib_bitmap_zero (ldpw->libc_wr_bitmap);
   clib_bitmap_zero (ldpw->ex_bitmap);
-  clib_bitmap_zero (ldpw->sid_ex_bitmap);
+  clib_bitmap_zero (ldpw->si_ex_bitmap);
   clib_bitmap_zero (ldpw->libc_ex_bitmap);
 
   return rv;
diff --git a/src/vcl/vcl_private.h b/src/vcl/vcl_private.h
index 0315a620f86..dd1d0cea440 100644
--- a/src/vcl/vcl_private.h
+++ b/src/vcl/vcl_private.h
@@ -90,6 +90,11 @@ typedef struct
   u32 et_mask;
 } vppcom_epoll_t;
 
+/* Select uses the vcl_si_set as if a clib_bitmap. Make sure they are the
+ * same size */
+STATIC_ASSERT (sizeof (clib_bitmap_t) == sizeof (vcl_si_set),
+	       "vppcom bitmap size mismatch");
+
 typedef struct
 {
   u8 is_ip4;
diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 2c2cb2c186b..54c5f10284d 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -2043,18 +2043,17 @@ vppcom_session_write_ready (vcl_session_t * session)
   /* Assumes caller has acquired spinlock: vcm->sessions_lockp */
   if (PREDICT_FALSE (session->is_vep))
     {
-      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
-		    "cannot write to an epoll session!",
-		    getpid (), session->vpp_handle, session->session_index);
+      VDBG (0, "session %u [0x%llx]: cannot write to an epoll session!",
+	    session->session_index, session->vpp_handle);
       return VPPCOM_EBADFD;
     }
 
   if (PREDICT_FALSE (session->session_state & STATE_LISTEN))
     {
-      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
-		    "cannot write to a listen session!",
-		    getpid (), session->vpp_handle, session->session_index);
-      return VPPCOM_EBADFD;
+      if (session->tx_fifo)
+	return svm_fifo_max_enqueue (session->tx_fifo);
+      else
+	return VPPCOM_EBADFD;
     }
 
   if (PREDICT_FALSE (!(session->session_state & STATE_OPEN)))
@@ -2063,19 +2062,13 @@ vppcom_session_write_ready (vcl_session_t * session)
       int rv;
 
       rv = ((state & STATE_DISCONNECT) ? VPPCOM_ECONNRESET : VPPCOM_ENOTCONN);
-      clib_warning ("VCL<%d>: ERROR: vpp handle 0x%llx, sid %u: "
-		    "session is not open! state 0x%x (%s), "
-		    "returning %d (%s)", getpid (), session->vpp_handle,
-		    session->session_index,
-		    state, vppcom_session_state_str (state),
-		    rv, vppcom_retval_str (rv));
+      VDBG (0, "session %u [0x%llx]: session is not open! state 0x%x (%s), "
+	    "returning %d (%s)", session->session_index, session->vpp_handle,
+	    state, vppcom_session_state_str (state), rv,
+	    vppcom_retval_str (rv));
       return rv;
     }
 
-  VDBG (3, "VCL<%d>: vpp handle 0x%llx, sid %u: peek %s (%p), ready = %d",
-	getpid (), session->vpp_handle, session->session_index,
-	session->tx_fifo, svm_fifo_max_enqueue (session->tx_fifo));
-
   return svm_fifo_max_enqueue (session->tx_fifo);
 }
 
@@ -2248,15 +2241,15 @@ vcl_select_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
 }
 
 static int
-vppcom_select_condvar (vcl_worker_t * wrk, unsigned long n_bits,
-		       unsigned long *read_map, unsigned long *write_map,
-		       unsigned long *except_map, double time_to_wait,
+vppcom_select_condvar (vcl_worker_t * wrk, int n_bits,
+		       vcl_si_set * read_map, vcl_si_set * write_map,
+		       vcl_si_set * except_map, double time_to_wait,
 		       u32 * bits_set)
 {
   double total_wait = 0, wait_slice;
   vcl_cut_through_registration_t *cr;
 
-  time_to_wait = (time_to_wait == -1) ? 10e9 : time_to_wait;
+  time_to_wait = (time_to_wait == -1) ? 1e6 : time_to_wait;
   wait_slice = wrk->cut_through_registrations ? 10e-6 : time_to_wait;
   do
     {
@@ -2270,7 +2263,7 @@ vppcom_select_condvar (vcl_worker_t * wrk, unsigned long n_bits,
       vcl_ct_registration_unlock (wrk);
 
       vcl_select_handle_mq (wrk, wrk->app_event_queue, n_bits, read_map,
-			    write_map, except_map, time_to_wait, bits_set);
+			    write_map, except_map, wait_slice, bits_set);
       total_wait += wait_slice;
       if (*bits_set)
 	return *bits_set;
@@ -2281,9 +2274,9 @@ vppcom_select_condvar (vcl_worker_t * wrk, unsigned long n_bits,
 }
 
 static int
-vppcom_select_eventfd (vcl_worker_t * wrk, unsigned long n_bits,
-		       unsigned long *read_map, unsigned long *write_map,
-		       unsigned long *except_map, double time_to_wait,
+vppcom_select_eventfd (vcl_worker_t * wrk, int n_bits,
+		       vcl_si_set * read_map, vcl_si_set * write_map,
+		       vcl_si_set * except_map, double time_to_wait,
 		       u32 * bits_set)
 {
   vcl_mq_evt_conn_t *mqc;
@@ -2306,44 +2299,34 @@ vppcom_select_eventfd (vcl_worker_t * wrk, unsigned long n_bits,
 }
 
 int
-vppcom_select (unsigned long n_bits, unsigned long *read_map,
-	       unsigned long *write_map, unsigned long *except_map,
-	       double time_to_wait)
+vppcom_select (int n_bits, vcl_si_set * read_map, vcl_si_set * write_map,
+	       vcl_si_set * except_map, double time_to_wait)
 {
   u32 sid, minbits = clib_max (n_bits, BITS (uword)), bits_set = 0;
   vcl_worker_t *wrk = vcl_worker_get_current ();
   vcl_session_t *session = 0;
   int rv, i;
 
-  STATIC_ASSERT (sizeof (clib_bitmap_t) == sizeof (unsigned long),
-		 "vppcom bitmap size mismatch");
-  STATIC_ASSERT (sizeof (clib_bitmap_t) == sizeof (fd_mask),
-		 "vppcom bitmap size mismatch");
-  STATIC_ASSERT (sizeof (clib_bitmap_t) == sizeof (uword),
-		 "vppcom bitmap size mismatch");
-
   if (n_bits && read_map)
     {
       clib_bitmap_validate (wrk->rd_bitmap, minbits);
       clib_memcpy_fast (wrk->rd_bitmap, read_map,
-			vec_len (wrk->rd_bitmap) * sizeof (unsigned long));
-      memset (read_map, 0, vec_len (wrk->rd_bitmap) * sizeof (unsigned long));
+			vec_len (wrk->rd_bitmap) * sizeof (vcl_si_set));
+      memset (read_map, 0, vec_len (wrk->rd_bitmap) * sizeof (vcl_si_set));
     }
   if (n_bits && write_map)
     {
       clib_bitmap_validate (wrk->wr_bitmap, minbits);
       clib_memcpy_fast (wrk->wr_bitmap, write_map,
-			vec_len (wrk->wr_bitmap) * sizeof (unsigned long));
-      memset (write_map, 0,
-	      vec_len (wrk->wr_bitmap) * sizeof (unsigned long));
+			vec_len (wrk->wr_bitmap) * sizeof (vcl_si_set));
+      memset (write_map, 0, vec_len (wrk->wr_bitmap) * sizeof (vcl_si_set));
     }
   if (n_bits && except_map)
     {
       clib_bitmap_validate (wrk->ex_bitmap, minbits);
       clib_memcpy_fast (wrk->ex_bitmap, except_map,
-			vec_len (wrk->ex_bitmap) * sizeof (unsigned long));
-      memset (except_map, 0,
-	      vec_len (wrk->ex_bitmap) * sizeof (unsigned long));
+			vec_len (wrk->ex_bitmap) * sizeof (vcl_si_set));
+      memset (except_map, 0, vec_len (wrk->ex_bitmap) * sizeof (vcl_si_set));
     }
 
   if (!n_bits)
@@ -2367,6 +2350,8 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
         clib_bitmap_set_no_check ((uword*)write_map, sid, 1);
         bits_set++;
       }
+    else
+      svm_fifo_set_want_tx_evt (session->tx_fifo, 1);
   }));
 
 check_rd:
diff --git a/src/vcl/vppcom.h b/src/vcl/vppcom.h
index 513947a559e..d82c9f9c58c 100644
--- a/src/vcl/vppcom.h
+++ b/src/vcl/vppcom.h
@@ -173,6 +173,8 @@ typedef struct vppcom_data_segment_
 
 typedef vppcom_data_segment_t vppcom_data_segments_t[2];
 
+typedef unsigned long vcl_si_set;
+
 /*
  * VPPCOM Public API Functions
  */
@@ -259,10 +261,9 @@ extern int vppcom_session_write (uint32_t session_handle, void *buf,
 extern int vppcom_session_write_msg (uint32_t session_handle, void *buf,
 				     size_t n);
 
-extern int vppcom_select (unsigned long n_bits,
-			  unsigned long *read_map,
-			  unsigned long *write_map,
-			  unsigned long *except_map, double wait_for_time);
+extern int vppcom_select (int n_bits, vcl_si_set * read_map,
+			  vcl_si_set * write_map, vcl_si_set * except_map,
+			  double wait_for_time);
 
 extern int vppcom_epoll_create (void);
 extern int vppcom_epoll_ctl (uint32_t vep_handle, int op,