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[Qemu-devel] [PATCH 05/12] nbd: do not leak nbd_trip coroutines when a c
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 05/12] nbd: do not leak nbd_trip coroutines when a connection is torn down |
Date: |
Wed, 19 Sep 2012 15:49:49 +0200 |
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 <address@hidden>
---
nbd.c | 33 +++++++++++++++++++++++++++------
nbd.h | 1 +
2 file modificati, 28 inserzioni(+), 6 rimozioni(-)
diff --git a/nbd.c b/nbd.c
index 4aeb80a..eb72f4a 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;
diff --git a/nbd.h b/nbd.h
index a9038dc..8b84a50 100644
--- a/nbd.h
+++ b/nbd.h
@@ -84,6 +84,7 @@ void nbd_export_close(NBDExport *exp);
NBDClient *nbd_client_new(NBDExport *exp, int csock,
void (*close)(NBDClient *));
+void nbd_client_close(NBDClient *client);
void nbd_client_get(NBDClient *client);
void nbd_client_put(NBDClient *client);
--
1.7.12
- [Qemu-devel] [PULL 00/12] NBD patches for 2012-09-22, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 01/12] nbd: add more constants, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 03/12] nbd: do not close BlockDriverState in nbd_export_close, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 02/12] nbd: pass NBDClient to nbd_send_negotiate, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 04/12] nbd: make refcount interface public, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 05/12] nbd: do not leak nbd_trip coroutines when a connection is torn down,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 06/12] nbd: add reference counting to NBDExport, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 08/12] nbd: add notification for closing an NBDExport, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 11/12] nbd: negotiate with named exports, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 07/12] nbd: track clients into NBDExport, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 09/12] qemu-nbd: rewrite termination conditions to use a state machine, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 10/12] nbd: register named exports, Paolo Bonzini, 2012/09/19
- [Qemu-devel] [PATCH 12/12] nbd: add nbd_export_get_blockdev, Paolo Bonzini, 2012/09/19
- Re: [Qemu-devel] [PULL 00/12] NBD patches for 2012-09-22, Anthony Liguori, 2012/09/25