vcl: epoll error handling fixes and improvements

- return VPPCOM_EEXIST if attempting to re-add a session
- return VPPCOM_ENOENT if the session to be removed is not epolled
- generate EPOLLIN if adding it through a mod operation on a session
that has data and did not have the event previously set.

Type: fix

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I728a06b8cf84af8d8c1dea7406e284de8886dffc
(cherry picked from commit 2645f68985df4955fd8a161224595dad9f4ab488)

2 files changed, 22 insertions, 6 deletions

diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 28f46f17b93..e98f9b7c84a 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -2713,6 +2713,12 @@ vppcom_epoll_ctl (uint32_t vep_handle, int op, uint32_t session_handle,
 	  VDBG (0, "EPOLL_CTL_ADD: NULL pointer to epoll_event structure!");
 	  return VPPCOM_EINVAL;
 	}
+      if (s->flags & VCL_SESSION_F_IS_VEP_SESSION)
+	{
+	  VDBG (0, "EPOLL_CTL_ADD: %u already epolled!", s->session_index);
+	  rv = VPPCOM_EEXIST;
+	  goto done;
+	}
       if (vep_session->vep.next_sh != ~0)
 	{
 	  vcl_session_t *next_session;
@@ -2771,7 +2777,7 @@ vppcom_epoll_ctl (uint32_t vep_handle, int op, uint32_t session_handle,
       else if (PREDICT_FALSE (!(s->flags & VCL_SESSION_F_IS_VEP_SESSION)))
 	{
 	  VDBG (0, "sh %u EPOLL_CTL_MOD: not a vep session!", session_handle);
-	  rv = VPPCOM_EINVAL;
+	  rv = VPPCOM_ENOENT;
 	  goto done;
 	}
       else if (PREDICT_FALSE (s->vep.vep_sh != vep_handle))
@@ -2782,15 +2788,24 @@ vppcom_epoll_ctl (uint32_t vep_handle, int op, uint32_t session_handle,
 	  goto done;
 	}
 
-      /* Generate EPOLLOUT when tx_fifo/ct_tx_fifo not full */
-      if ((event->events & EPOLLOUT) &&
-	  !(s->vep.ev.events & EPOLLOUT) && (vcl_session_write_ready (s) > 0))
+      /* Generate EPOLLOUT if session write ready nd event was not on */
+      if ((event->events & EPOLLOUT) && !(s->vep.ev.events & EPOLLOUT) &&
+	  (vcl_session_write_ready (s) > 0))
 	{
 	  session_event_t e = { 0 };
 	  e.event_type = SESSION_IO_EVT_TX;
 	  e.session_index = s->session_index;
 	  vec_add1 (wrk->unhandled_evts_vector, e);
 	}
+      /* Generate EPOLLIN if session read ready and event was not on */
+      if ((event->events & EPOLLIN) && !(s->vep.ev.events & EPOLLIN) &&
+	  (vcl_session_read_ready (s) > 0))
+	{
+	  session_event_t e = { 0 };
+	  e.event_type = SESSION_IO_EVT_RX;
+	  e.session_index = s->session_index;
+	  vec_add1 (wrk->unhandled_evts_vector, e);
+	}
       s->vep.et_mask = VEP_DEFAULT_ET_MASK;
       s->vep.ev = *event;
       txf = vcl_session_is_ct (s) ? s->ct_tx_fifo : s->tx_fifo;
@@ -2809,7 +2824,7 @@ vppcom_epoll_ctl (uint32_t vep_handle, int op, uint32_t session_handle,
       if (PREDICT_FALSE (!(s->flags & VCL_SESSION_F_IS_VEP_SESSION)))
 	{
 	  VDBG (0, "EPOLL_CTL_DEL: %u not a vep session!", session_handle);
-	  rv = VPPCOM_EINVAL;
+	  rv = VPPCOM_ENOENT;
 	  goto done;
 	}
       else if (PREDICT_FALSE (s->vep.vep_sh != vep_handle))
diff --git a/src/vcl/vppcom.h b/src/vcl/vppcom.h
index ae157ccc8b4..c2a625e974e 100644
--- a/src/vcl/vppcom.h
+++ b/src/vcl/vppcom.h
@@ -98,7 +98,8 @@ typedef enum
   VPPCOM_ECONNREFUSED = -ECONNREFUSED,
   VPPCOM_ETIMEDOUT = -ETIMEDOUT,
   VPPCOM_EEXIST = -EEXIST,
-  VPPCOM_ENOPROTOOPT = -ENOPROTOOPT
+  VPPCOM_ENOPROTOOPT = -ENOPROTOOPT,
+  VPPCOM_ENOENT = -ENOENT,
 } vppcom_error_t;
 
 typedef enum