blktap2: Support for control op cancellation.

Make client disconnect cancel blocking operations.

Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>

diff --git a/drivers/tapdisk-control.c b/drivers/tapdisk-control.c
index f522e7447e2e7d6d244e66f0aaf541f138c77aa1..80cc01235f82fcbbe5b583871c55b7aa72122765 100644 (file)
--- a/drivers/tapdisk-control.c
+++ b/drivers/tapdisk-control.c
@@ -53,12 +53,13 @@ struct tapdisk_control {
        int                uuid;
        int                socket;
        int                event_id;
-       int                running;
+       int                busy;
 };
 
 struct tapdisk_control_connection {
        int                socket;
        event_id_t         event_id;
+       int                busy;
 };
 
 static struct tapdisk_control td_control;
@@ -106,21 +107,30 @@ tapdisk_control_allocate_connection(int fd)
 static void
 tapdisk_control_close_connection(struct tapdisk_control_connection *connection)
 {
-       tapdisk_server_unregister_event(connection->event_id);
-       close(connection->socket);
-       free(connection);
+       if (connection->event_id) {
+               tapdisk_server_unregister_event(connection->event_id);
+               connection->event_id = 0;
+       }
+
+       if (connection->socket >= 0) {
+               close(connection->socket);
+               connection->socket = -1;
+       }
+
+       if (!connection->busy)
+               free(connection);
 }
 
 static int
 tapdisk_control_read_message(int fd, tapdisk_message_t *message, int timeout)
 {
+       const int len = sizeof(tapdisk_message_t);
        fd_set readfds;
-       int ret, len, offset;
+       int ret, offset;
        struct timeval tv, *t;
 
        t      = NULL;
        offset = 0;
-       len    = sizeof(tapdisk_message_t);
 
        if (timeout) {
                tv.tv_sec  = timeout;
@@ -155,7 +165,7 @@ tapdisk_control_read_message(int fd, tapdisk_message_t *message, int timeout)
        DPRINTF("received '%s' message (uuid = %u)\n",
                tapdisk_message_name(message->type), message->cookie);
 
-       return 0;
+       return offset;
 }
 
 static int
@@ -570,7 +580,8 @@ tapdisk_control_pause_vbd(struct tapdisk_control_connection *connection,
                        break;
 
                tapdisk_server_iterate();
-       } while (1);
+
+       } while (connection->socket >= 0);
 
 out:
        response.cookie = request->cookie;
@@ -657,13 +668,13 @@ struct tapdisk_message_info {
 static void
 tapdisk_control_handle_request(event_id_t id, char mode, void *private)
 {
-       int err;
+       int err, len, excl;
        tapdisk_message_t message, response;
        struct tapdisk_control_connection *connection = private;
        struct tapdisk_message_info *info;
 
-       if (tapdisk_control_read_message(connection->socket, &message, 2)) {
-               EPRINTF("failed to read message from %d\n", connection->socket);
+       len = tapdisk_control_read_message(connection->socket, &message, 2);
+       if (len <= 0) {
                tapdisk_control_close_connection(connection);
                return;
        }
@@ -676,21 +687,25 @@ tapdisk_control_handle_request(event_id_t id, char mode, void *private)
                goto invalid;
 
        info = &message_infos[message.type];
-       if (!info)
+
+       if (!info->handler)
                goto invalid;
 
-       if (td_control.running && !(info->flags & TAPDISK_MSG_REENTER))
-               goto busy;
+       excl = !(info->flags & TAPDISK_MSG_REENTER);
 
-       td_control.running++;
+       if (excl) {
+               if (td_control.busy)
+                       goto busy;
 
-       tapdisk_server_mask_event(connection->event_id, 1);
+               td_control.busy++;
+       }
+       connection->busy++;
 
        info->handler(connection, &message);
 
-       tapdisk_server_mask_event(connection->event_id, 0);
-
-       td_control.running--;
+       connection->busy++;
+       if (excl)
+               td_control.busy--;
 
        return;