From 5842c83596fcfa742978ec2840440ab56c7fdf79 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Mon, 30 Oct 2017 15:41:01 -0700 Subject: [PATCH] xen/pvcalls: implement poll command For active sockets, check the indexes and use the inflight_conn_req waitqueue to wait. For passive sockets if an accept is outstanding (PVCALLS_FLAG_ACCEPT_INFLIGHT), check if it has been answered by looking at bedata->rsp[req_id]. If so, return POLLIN. Otherwise use the inflight_accept_req waitqueue. If no accepts are inflight, send PVCALLS_POLL to the backend. If we have outstanding POLL requests awaiting for a response use the inflight_req waitqueue: inflight_req is awaken when a new response is received; on wakeup we check whether the POLL response is arrived by looking at the PVCALLS_FLAG_POLL_RET flag. We set the flag from pvcalls_front_event_handler, if the response was for a POLL command. In pvcalls_front_event_handler, get the struct sock_mapping from the poll id (we previously converted struct sock_mapping* to uintptr_t and used it as id). Signed-off-by: Stefano Stabellini Reviewed-by: Boris Ostrovsky CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky --- drivers/xen/pvcalls-front.c | 144 +++++++++++++++++++++++++++++++++--- drivers/xen/pvcalls-front.h | 3 + 2 files changed, 138 insertions(+), 9 deletions(-) diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c index 24ffdc90e217..c7d4251c3678 100644 --- a/drivers/xen/pvcalls-front.c +++ b/drivers/xen/pvcalls-front.c @@ -83,6 +83,8 @@ struct sock_mapping { * Only one poll operation can be inflight for a given socket. */ #define PVCALLS_FLAG_ACCEPT_INFLIGHT 0 +#define PVCALLS_FLAG_POLL_INFLIGHT 1 +#define PVCALLS_FLAG_POLL_RET 2 uint8_t flags; uint32_t inflight_req_id; struct sock_mapping *accept_map; @@ -154,15 +156,32 @@ again: rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons); req_id = rsp->req_id; - dst = (uint8_t *)&bedata->rsp[req_id] + sizeof(rsp->req_id); - src = (uint8_t *)rsp + sizeof(rsp->req_id); - memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id)); - /* - * First copy the rest of the data, then req_id. It is - * paired with the barrier when accessing bedata->rsp. - */ - smp_wmb(); - bedata->rsp[req_id].req_id = rsp->req_id; + if (rsp->cmd == PVCALLS_POLL) { + struct sock_mapping *map = (struct sock_mapping *)(uintptr_t) + rsp->u.poll.id; + + clear_bit(PVCALLS_FLAG_POLL_INFLIGHT, + (void *)&map->passive.flags); + /* + * clear INFLIGHT, then set RET. It pairs with + * the checks at the beginning of + * pvcalls_front_poll_passive. + */ + smp_wmb(); + set_bit(PVCALLS_FLAG_POLL_RET, + (void *)&map->passive.flags); + } else { + dst = (uint8_t *)&bedata->rsp[req_id] + + sizeof(rsp->req_id); + src = (uint8_t *)rsp + sizeof(rsp->req_id); + memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id)); + /* + * First copy the rest of the data, then req_id. It is + * paired with the barrier when accessing bedata->rsp. + */ + smp_wmb(); + bedata->rsp[req_id].req_id = req_id; + } done = 1; bedata->ring.rsp_cons++; @@ -846,6 +865,113 @@ received: return ret; } +static unsigned int pvcalls_front_poll_passive(struct file *file, + struct pvcalls_bedata *bedata, + struct sock_mapping *map, + poll_table *wait) +{ + int notify, req_id, ret; + struct xen_pvcalls_request *req; + + if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags)) { + uint32_t req_id = READ_ONCE(map->passive.inflight_req_id); + + if (req_id != PVCALLS_INVALID_ID && + READ_ONCE(bedata->rsp[req_id].req_id) == req_id) + return POLLIN | POLLRDNORM; + + poll_wait(file, &map->passive.inflight_accept_req, wait); + return 0; + } + + if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET, + (void *)&map->passive.flags)) + return POLLIN | POLLRDNORM; + + /* + * First check RET, then INFLIGHT. No barriers necessary to + * ensure execution ordering because of the conditional + * instructions creating control dependencies. + */ + + if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT, + (void *)&map->passive.flags)) { + poll_wait(file, &bedata->inflight_req, wait); + return 0; + } + + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { + spin_unlock(&bedata->socket_lock); + return ret; + } + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_POLL; + req->u.poll.id = (uintptr_t) map; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->socket_lock); + if (notify) + notify_remote_via_irq(bedata->irq); + + poll_wait(file, &bedata->inflight_req, wait); + return 0; +} + +static unsigned int pvcalls_front_poll_active(struct file *file, + struct pvcalls_bedata *bedata, + struct sock_mapping *map, + poll_table *wait) +{ + unsigned int mask = 0; + int32_t in_error, out_error; + struct pvcalls_data_intf *intf = map->active.ring; + + out_error = intf->out_error; + in_error = intf->in_error; + + poll_wait(file, &map->active.inflight_conn_req, wait); + if (pvcalls_front_write_todo(map)) + mask |= POLLOUT | POLLWRNORM; + if (pvcalls_front_read_todo(map)) + mask |= POLLIN | POLLRDNORM; + if (in_error != 0 || out_error != 0) + mask |= POLLERR; + + return mask; +} + +unsigned int pvcalls_front_poll(struct file *file, struct socket *sock, + poll_table *wait) +{ + struct pvcalls_bedata *bedata; + struct sock_mapping *map; + int ret; + + pvcalls_enter(); + if (!pvcalls_front_dev) { + pvcalls_exit(); + return POLLNVAL; + } + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + map = (struct sock_mapping *) sock->sk->sk_send_head; + if (!map) { + pvcalls_exit(); + return POLLNVAL; + } + 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(); + return ret; +} + static const struct xenbus_device_id pvcalls_front_ids[] = { { "pvcalls" }, { "" } diff --git a/drivers/xen/pvcalls-front.h b/drivers/xen/pvcalls-front.h index de24041e9a86..25e05b8f2d72 100644 --- a/drivers/xen/pvcalls-front.h +++ b/drivers/xen/pvcalls-front.h @@ -20,5 +20,8 @@ int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, int flags); +unsigned int pvcalls_front_poll(struct file *file, + struct socket *sock, + poll_table *wait); #endif