From 64d6871827b1e2ac8c9daf49f2c883378c7d50cd Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Wed, 14 Feb 2018 10:28:23 -0800 Subject: [PATCH] pvcalls-front: introduce a per sock_mapping refcount 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 Acked-by: Juergen Gross Signed-off-by: Juergen Gross --- 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 753d9cb437d0..11ce470b41a5 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->dev); - map = (struct sock_mapping *) sock->sk->sk_send_head; - if (!map) { - pvcalls_exit(); - return -ENOTSOCK; - } - mutex_lock(&map->active.in_mutex); if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) len = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); @@ -623,7 +626,7 @@ int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, ret = 0; mutex_unlock(&map->active.in_mutex); - pvcalls_exit(); + pvcalls_exit_sock(sock); return ret; } @@ -637,24 +640,16 @@ int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len) 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 == NULL) { - 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; } req = RING_GET_REQUEST(&bedata->ring, req_id); @@ -684,7 +679,7 @@ int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len) bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; map->passive.status = PVCALLS_STATUS_BIND; - pvcalls_exit(); + pvcalls_exit_sock(sock); return 0; } @@ -695,21 +690,13 @@ int pvcalls_front_listen(struct socket *sock, int backlog) struct xen_pvcalls_request *req; int notify, req_id, ret; - 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; - } - if (map->passive.status != PVCALLS_STATUS_BIND) { - pvcalls_exit(); + pvcalls_exit_sock(sock); return -EOPNOTSUPP; } @@ -717,7 +704,7 @@ int pvcalls_front_listen(struct socket *sock, int backlog) ret = get_request(bedata, &req_id); if (ret < 0) { spin_unlock(&bedata->socket_lock); - pvcalls_exit(); + pvcalls_exit_sock(sock); return ret; } req = RING_GET_REQUEST(&bedata->ring, req_id); @@ -741,7 +728,7 @@ int pvcalls_front_listen(struct socket *sock, int backlog) bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID; map->passive.status = PVCALLS_STATUS_LISTEN; - pvcalls_exit(); + pvcalls_exit_sock(sock); return ret; } @@ -753,21 +740,13 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) struct xen_pvcalls_request *req; int notify, req_id, ret, evtchn, nonblock; - 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; - } - if (map->passive.status != PVCALLS_STATUS_LISTEN) { - pvcalls_exit(); + pvcalls_exit_sock(sock); return -EINVAL; } @@ -785,13 +764,13 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) goto received; } if (nonblock) { - pvcalls_exit(); + pvcalls_exit_sock(sock); return -EAGAIN; } if (wait_event_interruptible(map->passive.inflight_accept_req, !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags))) { - pvcalls_exit(); + pvcalls_exit_sock(sock); return -EINTR; } } @@ -802,7 +781,7 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); spin_unlock(&bedata->socket_lock); - pvcalls_exit(); + pvcalls_exit_sock(sock); return ret; } map2 = kzalloc(sizeof(*map2), GFP_ATOMIC); @@ -810,7 +789,7 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); spin_unlock(&bedata->socket_lock); - pvcalls_exit(); + pvcalls_exit_sock(sock); return -ENOMEM; } ret = create_active(map2, &evtchn); @@ -819,7 +798,7 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); spin_unlock(&bedata->socket_lock); - pvcalls_exit(); + pvcalls_exit_sock(sock); return ret; } list_add_tail(&map2->list, &bedata->socket_mappings); @@ -841,13 +820,13 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) /* We could check if we have received a response before returning. */ if (nonblock) { WRITE_ONCE(map->passive.inflight_req_id, req_id); - pvcalls_exit(); + pvcalls_exit_sock(sock); return -EAGAIN; } if (wait_event_interruptible(bedata->inflight_req, READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) { - pvcalls_exit(); + pvcalls_exit_sock(sock); return -EINTR; } /* read req_id, then the content */ @@ -862,7 +841,7 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); pvcalls_front_free_map(bedata, map2); - pvcalls_exit(); + pvcalls_exit_sock(sock); return -ENOMEM; } newsock->sk->sk_send_head = (void *)map2; @@ -874,7 +853,7 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); wake_up(&map->passive.inflight_accept_req); - pvcalls_exit(); + pvcalls_exit_sock(sock); return ret; } @@ -965,23 +944,16 @@ __poll_t pvcalls_front_poll(struct file *file, struct socket *sock, struct sock_mapping *map; __poll_t ret; - pvcalls_enter(); - if (!pvcalls_front_dev) { - pvcalls_exit(); + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) return EPOLLNVAL; - } bedata = dev_get_drvdata(&pvcalls_front_dev->dev); - map = (struct sock_mapping *) sock->sk->sk_send_head; - if (!map) { - pvcalls_exit(); - return EPOLLNVAL; - } if (map->active_socket) ret = pvcalls_front_poll_active(file, bedata, map, wait); else ret = pvcalls_front_poll_passive(file, bedata, map, wait); - pvcalls_exit(); + pvcalls_exit_sock(sock); return ret; } @@ -995,25 +967,20 @@ int pvcalls_front_release(struct socket *sock) if (sock->sk == NULL) return 0; - pvcalls_enter(); - if (!pvcalls_front_dev) { - pvcalls_exit(); - return -EIO; + map = pvcalls_enter_sock(sock); + if (IS_ERR(map)) { + if (PTR_ERR(map) == -ENOTCONN) + return -EIO; + else + return 0; } - bedata = dev_get_drvdata(&pvcalls_front_dev->dev); - map = (struct sock_mapping *) sock->sk->sk_send_head; - if (map == NULL) { - pvcalls_exit(); - return 0; - } - 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; } sock->sk->sk_send_head = NULL; @@ -1043,10 +1010,10 @@ int pvcalls_front_release(struct socket *sock) /* * We need to make sure that sendmsg/recvmsg on this socket have * not started before we've cleared sk_send_head here. The - * easiest (though not optimal) way to guarantee this is to see - * that no pvcall (other than us) is in progress. + * easiest way to guarantee this is to see that no pvcalls + * (other than us) is in progress on this socket. */ - while (atomic_read(&pvcalls_refcount) > 1) + while (atomic_read(&map->refcount) > 1) cpu_relax(); pvcalls_front_free_map(bedata, map);