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authorPaolo Bonzini <pbonzini@redhat.com>2012-08-22 18:45:12 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2012-09-19 15:26:28 +0200
commitff2b68aa70d10b7eae813b04e9a23723dbd89ebd (patch)
tree3ddaf5829ccd5d60a14345cf0d5d6c4981bf6d2d /nbd.c
parentce33967af74523685c7f911f6576c689728fcc81 (diff)
downloadqemu-arm-ff2b68aa70d10b7eae813b04e9a23723dbd89ebd.tar.gz
nbd: do not leak nbd_trip coroutines when a connection is torn down
Because nbd_client_close removes the I/O handlers for the client socket, there is no way that any suspended coroutines are restarted. This will be a problem with the QEMU embedded NBD server, because we will have a QMP command to forcibly close all connections with the clients. Instead, we can exploit the reference counting of NBDClients; shutdown the client socket, which will make it readable and writeable. Also call the close callback, which will release the user's reference. The coroutines then will fail and exit cleanly, and release all remaining references, until the last refcount finally triggers the closure of the client. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'nbd.c')
-rw-r--r--nbd.c33
1 files changed, 27 insertions, 6 deletions
diff --git a/nbd.c b/nbd.c
index 4aeb80ae18..eb72f4a6e5 100644
--- a/nbd.c
+++ b/nbd.c
@@ -109,6 +109,7 @@ struct NBDClient {
Coroutine *send_coroutine;
int nb_requests;
+ bool closing;
};
/* That's all folks */
@@ -655,19 +656,35 @@ void nbd_client_get(NBDClient *client)
void nbd_client_put(NBDClient *client)
{
if (--client->refcount == 0) {
+ /* The last reference should be dropped by client->close,
+ * which is called by nbd_client_close.
+ */
+ assert(client->closing);
+
+ qemu_set_fd_handler2(client->sock, NULL, NULL, NULL, NULL);
+ close(client->sock);
+ client->sock = -1;
g_free(client);
}
}
-static void nbd_client_close(NBDClient *client)
+void nbd_client_close(NBDClient *client)
{
- qemu_set_fd_handler2(client->sock, NULL, NULL, NULL, NULL);
- close(client->sock);
- client->sock = -1;
+ if (client->closing) {
+ return;
+ }
+
+ client->closing = true;
+
+ /* Force requests to finish. They will drop their own references,
+ * then we'll close the socket and free the NBDClient.
+ */
+ shutdown(client->sock, 2);
+
+ /* Also tell the client, so that they release their reference. */
if (client->close) {
client->close(client);
}
- nbd_client_put(client);
}
static NBDRequest *nbd_request_get(NBDClient *client)
@@ -810,14 +827,18 @@ out:
static void nbd_trip(void *opaque)
{
NBDClient *client = opaque;
- NBDRequest *req = nbd_request_get(client);
NBDExport *exp = client->exp;
+ NBDRequest *req;
struct nbd_request request;
struct nbd_reply reply;
ssize_t ret;
TRACE("Reading request.");
+ if (client->closing) {
+ return;
+ }
+ req = nbd_request_get(client);
ret = nbd_co_receive_request(req, &request);
if (ret == -EAGAIN) {
goto done;