From: Steven <sluong@cisco.com>
Date: Wed, 22 Mar 2017 19:05:19 +0000 (-0700)
Subject: vhost: vhost-user component may become unusable with too many open files (VPP-668)
X-Git-Tag: v17.07-rc1~408
X-Git-Url: https://gerrit.fd.io/r/gitweb?a=commitdiff_plain;h=0d150bb132b81c20b38a0cefd82c8f718435515d;p=vpp.git

vhost: vhost-user component may become unusable with too many open files (VPP-668)

When the number of open files is reached in the system, vhost may
encounter a failure in socket call and return from vhost-user-process.
The return terminates all attempts of incoming socket connections
in the future, even if the condition is reconciled.

The fix is to not return from vhost-user-process, record the error in
the interface, spit out the error, and retry the connection every 3 seconds.

Change-Id: I806baedf13e8c9b73e7c7820c094240f39949950
Signed-off-by: Steven <sluong@cisco.com>
---

diff --git a/src/vnet/devices/virtio/vhost-user.c b/src/vnet/devices/virtio/vhost-user.c
index 5ad4cb62bee..00807dc0398 100644
--- a/src/vnet/devices/virtio/vhost-user.c
+++ b/src/vnet/devices/virtio/vhost-user.c
@@ -2440,14 +2440,11 @@ vhost_user_process (vlib_main_t * vm,
   f64 timeout = 3153600000.0 /* 100 years */ ;
   uword *event_data = 0;
 
-  sockfd = socket (AF_UNIX, SOCK_STREAM, 0);
+  sockfd = -1;
   sun.sun_family = AF_UNIX;
   template.read_function = vhost_user_socket_read;
   template.error_function = vhost_user_socket_error;
 
-  if (sockfd < 0)
-    return 0;
-
   while (1)
     {
       vlib_process_wait_for_event_or_clock (vm, timeout);
@@ -2462,6 +2459,23 @@ vhost_user_process (vlib_main_t * vm,
 	  if (vui->unix_server_index == ~0) { //Nothing to do for server sockets
 	      if (vui->unix_file_index == ~0)
 		{
+		  if ((sockfd < 0) &&
+		      ((sockfd = socket (AF_UNIX, SOCK_STREAM, 0)) < 0))
+		    {
+		      /*
+		       * 1st time error or new error for this interface,
+		       * spit out the message and record the error
+		       */
+		      if (!vui->sock_errno || (vui->sock_errno != errno))
+			{
+			  clib_unix_warning
+			    ("Error: Could not open unix socket for %s",
+			     vui->sock_filename);
+			  vui->sock_errno = errno;
+			}
+		      continue;
+		    }
+
 		  /* try to connect */
 		  strncpy (sun.sun_path, (char *) vui->sock_filename,
 			   sizeof (sun.sun_path) - 1);
@@ -2483,11 +2497,8 @@ vhost_user_process (vlib_main_t * vm,
 			  vui - vhost_user_main.vhost_user_interfaces;
 		      vui->unix_file_index = unix_file_add (&unix_main, &template);
 
-		      //Re-open for next connect
-		      if ((sockfd = socket (AF_UNIX, SOCK_STREAM, 0)) < 0) {
-			  clib_warning("Critical: Could not open unix socket");
-			  return 0;
-		      }
+		      /* This sockfd is considered consumed */
+		      sockfd = -1;
 		    }
 		  else
 		    {