pmlag

commit 0a1cd68d615a5c6064b6de949845a37f3bdefaa1
parent 5851fbeb8f3648f336c77c47eb8c371b696bd567
Author: Robin Bron <robin@finwo.nl>
Date:   Sun, 12 Feb 2023 23:58:44 +0100

Use mutex instead of sleep to let iface threads wait for the tap to exist

Diffstat:
M
src/config.h
 | 
25
+++++++++++++------------
M
src/main.c
 | 
18
++++++++++++++----

2 files changed, 27 insertions(+), 16 deletions(-)
diff --git a/src/config.h b/src/config.h
@@ -13,21 +13,22 @@ extern "C" {
 #define PMLAG_MODE_BALANCED_RR   3
 
 struct pmlag_iface {
-  void *next;
-  char *name;
-  int   weight;
-  int   sockfd;
-  pthread_t tid;
-  struct pmlag_bond *bond;
+  void *next;              // linked-list next reference
+  char *name;              // name of the interface this object represents
+  int   weight;            // weight of this interface within the bond
+  int   sockfd;            // file descriptor for the iface raw socket
+  pthread_t tid;           // thread id where the iface listener recides in
+  struct pmlag_bond *bond; // reference to the bond this iface belongs to
 };
 
 struct pmlag_bond {
-  void *next;
-  char *name;
-  int   mode;
-  int   sockfd;
-  pthread_t tid;
-  struct pmlag_iface *interfaces;
+  void *next;                     // linked-list next reference
+  char *name;                     // name of the bond interface
+  int   mode;                     // which mode to run pmlag in for this bond
+  int   sockfd;                   // file descriptor for the bond socket interface
+  pthread_t tid;                  // thread id where the bond interface listener recides in
+  pthread_mutex_t mtx_rt;         // lock for the routing table of the bond
+  struct pmlag_iface *interfaces; // linked-list of interfaces contained in the bond
 };
 
 struct pmlag_configuration {
diff --git a/src/main.c b/src/main.c
@@ -44,9 +44,9 @@ void * thread_iface(void *arg) {
 
   printf("Thread started for iface: %s->%s(%d)\n", iface->bond->name, iface->name, iface->sockfd);
 
-  // Allow some time for all threads to register their sockets
-  // TODO: use a mutex from main thread for this to not have idle-time?
-  sleep(1);
+  // Wait for the bond thread to finish initializing
+  pthread_mutex_lock(&(iface->bond->mtx_rt));
+  pthread_mutex_unlock(&(iface->bond->mtx_rt));
 
   // Bail if the bond's socket could not be opened
   if (!iface->bond->sockfd) {
@@ -97,7 +97,8 @@ void * thread_bond(void *arg) {
   struct pmlag_bond *bond = (struct pmlag_bond *)arg;
   printf("Thread started for bond: %s\n", bond->name);
 
-
+  // Lock this bond's routing table
+  pthread_mutex_lock(&(bond->mtx_rt));
 
   // Start thread for each interface of this bond
   struct pmlag_iface *iface = bond->interfaces;
@@ -113,6 +114,9 @@ void * thread_bond(void *arg) {
   // Take mac address of last iface
   bond->sockfd = tap_alloc(bond->name);
 
+  // Free this bond's routing table
+  pthread_mutex_unlock(&(bond->mtx_rt));
+
   // TODO: blocked listen on bond, send through routing table to other ifaces
   // TODO: send broadcasts to all interfaces
   // TODO: timer to broadcast announce our presence to ifaces (vrrp-ish)
@@ -159,6 +163,12 @@ int main(int argc, const char **argv) {
   // For each bond of config->bonds
   struct pmlag_bond *bond = config->bonds;
   while(bond) {
+    // Initialize it's routing table lock
+    if (pthread_mutex_init(&(bond->mtx_rt), NULL) != 0) {
+      perror("Initializing mutex for bond");
+      return 1;
+    }
+    // And start it's thread
     if(pthread_create(&(bond->tid), NULL, thread_bond, bond)) {
       perror("Starting bond thread");
       return 1;