trace-cmd/listen: Force search of unique port

On some systems, the code to find a unique udp port may
give a invalid success of the previous port. Which causes two
child process to listen to the same port, and makes one of them
fail.

Force the start of the port search to the port after the last
port found, to prevent the same port from being used by two
listeners.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/trace-listen.c b/trace-listen.c
index e8c9ba9..e60c96b 100644
--- a/trace-listen.c
+++ b/trace-listen.c
@@ -231,13 +231,13 @@ static void process_udp_child(int sfd, const char *host, const char *port,
 #define MAX_PORT_SEARCH 6000
 
 static int open_udp(const char *node, const char *port, int *pid,
-                    int cpu, int pagesize)
+                    int cpu, int pagesize, int start_port)
 {
         struct addrinfo hints;
         struct addrinfo *result, *rp;
         int sfd, s;
         char buf[BUFSIZ];
-        int num_port = START_PORT_SEARCH;
+        int num_port = start_port;
 
  again:
         snprintf(buf, BUFSIZ, "%d", num_port);
@@ -293,6 +293,7 @@ static void process_client(const char *node, const char *port, int fd)
         int *port_array;
         int *pid_array;
         int pagesize;
+        int start_port;
         int udp_port;
         int options;
         int size;
@@ -379,13 +380,17 @@ static void process_client(const char *node, const char *port, int fd)
         pid_array = malloc_or_die(sizeof(int) * cpus);
         memset(pid_array, 0, sizeof(int) * cpus);
 
+        start_port = START_PORT_SEARCH;
+
         /* Now create a UDP port for each CPU */
         for (cpu = 0; cpu < cpus; cpu++) {
-                udp_port = open_udp(node, port, &pid, cpu, pagesize);
+                udp_port = open_udp(node, port, &pid, cpu, pagesize, start_port);
                 if (udp_port < 0)
                         goto out_free;
                 port_array[cpu] = udp_port;
                 pid_array[cpu] = pid;
+                /* due to some bugging finding ports, force search after last port */
+                start_port = udp_port+1;
         }
 
         /* send the client a comma deliminated set of port numbers */