Introduce a per sock_mapping refcount, in addition to the existing
global refcount. Thanks to the sock_mapping refcount, we can safely wait
for it to be 1 in pvcalls_front_release before freeing an active socket,
instead of waiting for the global refcount to be 1.
Signed-off-by: Stefano Stabellini
---
Changes in v3:
- remove pointless initializers
- reorder pvcalls_enter_sock
---
drivers/xen/pvcalls-front.c | 191 ++--
1 file changed, 79 insertions(+), 112 deletions(-)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index 4c789e6..18d1bac 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -60,6 +60,7 @@ struct sock_mapping {
bool active_socket;
struct list_head list;
struct socket *sock;
+ atomic_t refcount;
union {
struct {
int irq;
@@ -93,6 +94,32 @@ struct sock_mapping {
};
};
+static inline struct sock_mapping *pvcalls_enter_sock(struct socket *sock)
+{
+ struct sock_mapping *map;
+
+ if (!pvcalls_front_dev ||
+ dev_get_drvdata(&pvcalls_front_dev->dev) == NULL)
+ return ERR_PTR(-ENOTCONN);
+
+ map = (struct sock_mapping *)sock->sk->sk_send_head;
+ if (map == NULL)
+ return ERR_PTR(-ENOTSOCK);
+
+ pvcalls_enter();
+ atomic_inc(&map->refcount);
+ return map;
+}
+
+static inline void pvcalls_exit_sock(struct socket *sock)
+{
+ struct sock_mapping *map;
+
+ map = (struct sock_mapping *)sock->sk->sk_send_head;
+ atomic_dec(&map->refcount);
+ pvcalls_exit();
+}
+
static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
{
*req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
@@ -369,31 +396,23 @@ int pvcalls_front_connect(struct socket *sock, struct
sockaddr *addr,
if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
return -EOPNOTSUPP;
- pvcalls_enter();
- if (!pvcalls_front_dev) {
- pvcalls_exit();
- return -ENOTCONN;
- }
+ map = pvcalls_enter_sock(sock);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
- map = (struct sock_mapping *)sock->sk->sk_send_head;
- if (!map) {
- pvcalls_exit();
- return -ENOTSOCK;
- }
-
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
- pvcalls_exit();
+ pvcalls_exit_sock(sock);
return ret;
}
ret = create_active(map, &evtchn);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
- pvcalls_exit();
+ pvcalls_exit_sock(sock);
return ret;
}
@@ -423,7 +442,7 @@ int pvcalls_front_connect(struct socket *sock, struct
sockaddr *addr,
smp_rmb();
ret = bedata->rsp[req_id].ret;
bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
- pvcalls_exit();
+ pvcalls_exit_sock(sock);
return ret;
}
@@ -488,23 +507,15 @@ int pvcalls_front_sendmsg(struct socket *sock, struct
msghdr *msg,
if (flags & (MSG_CONFIRM|MSG_DONTROUTE|MSG_EOR|MSG_OOB))
return -EOPNOTSUPP;
- pvcalls_enter();
- if (!pvcalls_front_dev) {
- pvcalls_exit();
- return -ENOTCONN;
- }
+ map = pvcalls_enter_sock(sock);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
- map = (struct sock_mapping *) sock->sk->sk_send_head;
- if (!map) {
- pvcalls_exit();
- return -ENOTSOCK;
- }
-
mutex_lock(&map->active.out_mutex);
if ((flags & MSG_DONTWAIT) && !pvcalls_front_write_todo(map)) {
mutex_unlock(&map->active.out_mutex);
- pvcalls_exit();
+ pvcalls_exit_sock(sock);
return -EAGAIN;
}
if (len > INT_MAX)
@@ -526,7 +537,7 @@ int pvcalls_front_sendmsg(struct socket *sock, struct
msghdr *msg,
tot_sent = sent;
mutex_unlock(&map->active.out_mutex);
- pvcalls_exit();
+ pvcalls_exit_sock(sock);
return tot_sent;
}
@@ -591,19 +602,11 @@ int pvcalls_front_recvmsg(struct socket *sock, struct
msghdr *msg, size_t len,
if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC))
return -EOPNOTSUPP;
- pvcalls_enter();
- if (!pvcalls_front_dev) {
- pvcalls_exit();
- return -ENOTCONN;
- }
+ map = pvcalls_enter_sock(sock);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
bedata = dev_get_drvdata(&pvcalls_front_dev->
