[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 10/13] xen/pvcalls: implement poll command
For active sockets, check the indexes and use the inflight_conn_req waitqueue to wait. For passive sockets, send PVCALLS_POLL to the backend. Use the inflight_accept_req waitqueue if an accept is outstanding. Otherwise 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 socket pointer from the poll id (we previously converted struct socket* to uint64_t and used it as id). Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx> CC: boris.ostrovsky@xxxxxxxxxx CC: jgross@xxxxxxxx --- drivers/xen/pvcalls-front.c | 134 ++++++++++++++++++++++++++++++++++++++++---- drivers/xen/pvcalls-front.h | 3 + 2 files changed, 126 insertions(+), 11 deletions(-) diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c index b4ca569..833b717 100644 --- a/drivers/xen/pvcalls-front.c +++ b/drivers/xen/pvcalls-front.c @@ -130,17 +130,35 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id) rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons); req_id = rsp->req_id; - src = (uint8_t *)&bedata->rsp[req_id]; - src += sizeof(rsp->req_id); - dst = (uint8_t *)rsp; - dst += 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(); - WRITE_ONCE(bedata->rsp[req_id].req_id, rsp->req_id); + if (rsp->cmd == PVCALLS_POLL) { + struct socket *sock = (struct socket *) rsp->u.poll.id; + struct sock_mapping *map = + (struct sock_mapping *) + READ_ONCE(sock->sk->sk_send_head); + + set_bit(PVCALLS_FLAG_POLL_RET, + (void *)&map->passive.flags); + /* + * Set RET, then clear INFLIGHT. It pairs with + * the checks at the beginning of + * pvcalls_front_poll_passive. + */ + smp_wmb(); + clear_bit(PVCALLS_FLAG_POLL_INFLIGHT, + (void *)&map->passive.flags); + } else { + src = (uint8_t *)&bedata->rsp[req_id]; + src += sizeof(rsp->req_id); + dst = (uint8_t *)rsp; + dst += 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(); + WRITE_ONCE(bedata->rsp[req_id].req_id, rsp->req_id); + } done = 1; bedata->ring.rsp_cons++; @@ -707,6 +725,100 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) 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; + struct xen_pvcalls_request *req; + + if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags)) { + 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; + + /* + * 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->pvcallss_lock); + req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1); + if (RING_FULL(&bedata->ring) || + READ_ONCE(bedata->rsp[req_id].req_id) != PVCALLS_INVALID_ID) { + spin_unlock(&bedata->pvcallss_lock); + return -EAGAIN; + } + req = RING_GET_REQUEST(&bedata->ring, req_id); + req->req_id = req_id; + req->cmd = PVCALLS_POLL; + req->u.poll.id = (uint64_t) map->sock; + + bedata->ring.req_prod_pvt++; + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); + spin_unlock(&bedata->pvcallss_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; + + if (!pvcalls_front_dev) + return POLLNVAL; + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + + map = (struct sock_mapping *) READ_ONCE(sock->sk->sk_send_head); + if (!map) + return POLLNVAL; + if (map->active_socket) + return pvcalls_front_poll_active(file, bedata, map, wait); + else + return pvcalls_front_poll_passive(file, bedata, map, wait); +} + 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 de24041..25e05b8 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 -- 1.9.1 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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