From 73e227959e02c3484085ce05c466a3ea0f3e5065 Mon Sep 17 00:00:00 2001
From: Johann Latocha
Date: Sat, 11 Feb 2012 01:34:07 +0100
Subject: [SERVER] Spinlocks to freeze threads while reloading config

---
 src/server/ipc.c    |  2 --
 src/server/net.c    | 11 +++++------
 src/server/server.c |  3 +--
 src/server/server.h |  2 +-
 src/server/utils.c  |  9 ++++++++-
 5 files changed, 15 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/src/server/ipc.c b/src/server/ipc.c
index 4adbb7e..1ae401b 100644
--- a/src/server/ipc.c
+++ b/src/server/ipc.c
@@ -88,9 +88,7 @@ void* dnbd3_ipc_receive()
 
         case IPC_RELOAD:
             printf("INFO: Reloading configuration...\n");
-            pthread_spin_lock(&_spinlock);
             dnbd3_reload_config(_config_file_name);
-            pthread_spin_unlock(&_spinlock);
             break;
 
         case IPC_INFO:
diff --git a/src/server/net.c b/src/server/net.c
index e4be703..ab01f70 100644
--- a/src/server/net.c
+++ b/src/server/net.c
@@ -41,7 +41,6 @@ void *dnbd3_handle_query(void *dnbd3_client)
     dnbd3_reply_t reply;
 
     int image_file = -1;
-    dnbd3_image_t *image;
 
     struct in_addr server;
     int i = 0;
@@ -52,10 +51,6 @@ void *dnbd3_handle_query(void *dnbd3_client)
         reply.error = 0;
         memcpy(reply.handle, request.handle, sizeof(request.handle));
 
-        // TODO: lock CMD_GET_SERVERS and CMD_GET_SIZE because of reloading cfg...
-        // pthread_spin_lock(&_spinlock);
-        // pthread_spin_unlock(&_spinlock);
-
         switch (request.cmd)
         {
         case CMD_GET_SERVERS:
@@ -67,6 +62,7 @@ void *dnbd3_handle_query(void *dnbd3_client)
                 continue;
             }
 
+            pthread_spin_lock(&client->spinlock);
             if (client->image->num_servers < MAX_NUMBER_SERVERS)
                 reply.size = client->image->num_servers * sizeof(struct in_addr);
             else
@@ -79,10 +75,13 @@ void *dnbd3_handle_query(void *dnbd3_client)
                 inet_aton(client->image->servers[i], &server);
                 send(client->sock, (char *) &server, sizeof(struct in_addr), 0);
             }
+            pthread_spin_unlock(&client->spinlock);
             continue;
 
         case CMD_GET_SIZE:
-            image = dnbd3_get_image(request.vid, request.rid);
+            pthread_spin_lock(&client->spinlock);
+            dnbd3_image_t *image = dnbd3_get_image(request.vid, request.rid);
+            pthread_spin_unlock(&client->spinlock);
 
             if(!image)
             { // image not found, send error
diff --git a/src/server/server.c b/src/server/server.c
index 786cc40..6fdedf0 100644
--- a/src/server/server.c
+++ b/src/server/server.c
@@ -37,7 +37,6 @@
 int _sock;
 
 GSList *_dnbd3_clients = NULL;
-pthread_spinlock_t _spinlock;
 char *_config_file_name = DEFAULT_SERVER_CONFIG_FILE;
 dnbd3_image_t *_images;
 size_t _num_images = 0;
@@ -137,7 +136,6 @@ int main(int argc, char* argv[])
         daemon(1, 0);
 
     // load config file
-    pthread_spin_init(&_spinlock, PTHREAD_PROCESS_PRIVATE);
     dnbd3_load_config(_config_file_name);
 
     // setup signal handler
@@ -178,6 +176,7 @@ int main(int argc, char* argv[])
 
         pthread_t thread;
         dnbd3_client_t *dnbd3_client = (dnbd3_client_t *) malloc(sizeof(dnbd3_client_t));
+        pthread_spin_init(&dnbd3_client->spinlock, PTHREAD_PROCESS_PRIVATE);
         strcpy(dnbd3_client->ip, inet_ntoa(client.sin_addr));
         dnbd3_client->sock = fd;
         dnbd3_client->thread = &thread;
diff --git a/src/server/server.h b/src/server/server.h
index 02da005..de9eccb 100644
--- a/src/server/server.h
+++ b/src/server/server.h
@@ -44,10 +44,10 @@ typedef struct
     char ip[16];
     pthread_t *thread;
     dnbd3_image_t *image;
+    pthread_spinlock_t spinlock;
 } dnbd3_client_t;
 
 extern GSList *_dnbd3_clients;
-extern pthread_spinlock_t _spinlock;
 extern char *_config_file_name;
 extern dnbd3_image_t *_images;
 extern size_t _num_images;
diff --git a/src/server/utils.c b/src/server/utils.c
index 3091b2f..be0b584 100644
--- a/src/server/utils.c
+++ b/src/server/utils.c
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <pthread.h>
 
 #include "server.h"
 #include "utils.h"
@@ -72,15 +73,21 @@ void dnbd3_load_config(char *file)
 
 void dnbd3_reload_config(char* config_file_name)
 {
-    _num_images = 0;
     GSList *iterator = NULL;
     for (iterator = _dnbd3_clients; iterator; iterator = iterator->next)
     {
         dnbd3_client_t *client = iterator->data;
+        pthread_spin_lock(&client->spinlock);
         client->image = NULL;
     }
+    _num_images = 0;
     free(_images);
     dnbd3_load_config(config_file_name);
+    for (iterator = _dnbd3_clients; iterator; iterator = iterator->next)
+    {
+        dnbd3_client_t *client = iterator->data;
+        pthread_spin_unlock(&client->spinlock);
+    }
 }
 
 dnbd3_image_t* dnbd3_get_image(int vid, int rid)
-- 
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