linux_dsm_epyc7002/drivers/xen/pvcalls-front.c

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/*
* (c) 2017 Stefano Stabellini <stefano@aporeto.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/module.h>
xen/pvcalls: implement socket command and handle events Send a PVCALLS_SOCKET command to the backend, use the masked req_prod_pvt as req_id. This way, req_id is guaranteed to be between 0 and PVCALLS_NR_REQ_PER_RING. We already have a slot in the rsp array ready for the response, and there cannot be two outstanding responses with the same req_id. Wait for the response by waiting on the inflight_req waitqueue and check for the req_id field in rsp[req_id]. Use atomic accesses and barriers to read the field. Note that the barriers are simple smp barriers (as opposed to virt barriers) because they are for internal frontend synchronization, not frontend<->backend communication. Once a response is received, clear the corresponding rsp slot by setting req_id to PVCALLS_INVALID_ID. Note that PVCALLS_INVALID_ID is invalid only from the frontend point of view. It is not part of the PVCalls protocol. pvcalls_front_event_handler is in charge of copying responses from the ring to the appropriate rsp slot. It is done by copying the body of the response first, then by copying req_id atomically. After the copies, wake up anybody waiting on waitqueue. socket_lock protects accesses to the ring. Convert the pointer to sock_mapping into an uintptr_t and use it as id for the new socket to pass to the backend. The struct will be fully initialized later on connect or bind. sock->sk->sk_send_head is not used for ip sockets: reuse the field to store a pointer to the struct sock_mapping corresponding to the socket. This way, we can easily get the struct sock_mapping from the struct socket. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-10-31 05:40:54 +07:00
#include <linux/net.h>
#include <linux/socket.h>
#include <net/sock.h>
#include <xen/events.h>
#include <xen/grant_table.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
#include <xen/interface/io/pvcalls.h>
xen/pvcalls: implement socket command and handle events Send a PVCALLS_SOCKET command to the backend, use the masked req_prod_pvt as req_id. This way, req_id is guaranteed to be between 0 and PVCALLS_NR_REQ_PER_RING. We already have a slot in the rsp array ready for the response, and there cannot be two outstanding responses with the same req_id. Wait for the response by waiting on the inflight_req waitqueue and check for the req_id field in rsp[req_id]. Use atomic accesses and barriers to read the field. Note that the barriers are simple smp barriers (as opposed to virt barriers) because they are for internal frontend synchronization, not frontend<->backend communication. Once a response is received, clear the corresponding rsp slot by setting req_id to PVCALLS_INVALID_ID. Note that PVCALLS_INVALID_ID is invalid only from the frontend point of view. It is not part of the PVCalls protocol. pvcalls_front_event_handler is in charge of copying responses from the ring to the appropriate rsp slot. It is done by copying the body of the response first, then by copying req_id atomically. After the copies, wake up anybody waiting on waitqueue. socket_lock protects accesses to the ring. Convert the pointer to sock_mapping into an uintptr_t and use it as id for the new socket to pass to the backend. The struct will be fully initialized later on connect or bind. sock->sk->sk_send_head is not used for ip sockets: reuse the field to store a pointer to the struct sock_mapping corresponding to the socket. This way, we can easily get the struct sock_mapping from the struct socket. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-10-31 05:40:54 +07:00
#include "pvcalls-front.h"
#define PVCALLS_INVALID_ID UINT_MAX
#define PVCALLS_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
#define PVCALLS_NR_RSP_PER_RING __CONST_RING_SIZE(xen_pvcalls, XEN_PAGE_SIZE)
#define PVCALLS_FRONT_MAX_SPIN 5000
struct pvcalls_bedata {
struct xen_pvcalls_front_ring ring;
grant_ref_t ref;
int irq;
struct list_head socket_mappings;
spinlock_t socket_lock;
wait_queue_head_t inflight_req;
struct xen_pvcalls_response rsp[PVCALLS_NR_RSP_PER_RING];
};
/* Only one front/back connection supported. */
static struct xenbus_device *pvcalls_front_dev;
static atomic_t pvcalls_refcount;
/* first increment refcount, then proceed */
#define pvcalls_enter() { \
atomic_inc(&pvcalls_refcount); \
}
/* first complete other operations, then decrement refcount */
#define pvcalls_exit() { \
atomic_dec(&pvcalls_refcount); \
}
struct sock_mapping {
bool active_socket;
struct list_head list;
struct socket *sock;
union {
struct {
int irq;
grant_ref_t ref;
struct pvcalls_data_intf *ring;
struct pvcalls_data data;
struct mutex in_mutex;
struct mutex out_mutex;
wait_queue_head_t inflight_conn_req;
} active;
struct {
/* Socket status */
#define PVCALLS_STATUS_UNINITALIZED 0
#define PVCALLS_STATUS_BIND 1
#define PVCALLS_STATUS_LISTEN 2
uint8_t status;
/*
* Internal state-machine flags.
* Only one accept operation can be inflight for a socket.
* 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;
wait_queue_head_t inflight_accept_req;
} passive;
};
};
xen/pvcalls: implement socket command and handle events Send a PVCALLS_SOCKET command to the backend, use the masked req_prod_pvt as req_id. This way, req_id is guaranteed to be between 0 and PVCALLS_NR_REQ_PER_RING. We already have a slot in the rsp array ready for the response, and there cannot be two outstanding responses with the same req_id. Wait for the response by waiting on the inflight_req waitqueue and check for the req_id field in rsp[req_id]. Use atomic accesses and barriers to read the field. Note that the barriers are simple smp barriers (as opposed to virt barriers) because they are for internal frontend synchronization, not frontend<->backend communication. Once a response is received, clear the corresponding rsp slot by setting req_id to PVCALLS_INVALID_ID. Note that PVCALLS_INVALID_ID is invalid only from the frontend point of view. It is not part of the PVCalls protocol. pvcalls_front_event_handler is in charge of copying responses from the ring to the appropriate rsp slot. It is done by copying the body of the response first, then by copying req_id atomically. After the copies, wake up anybody waiting on waitqueue. socket_lock protects accesses to the ring. Convert the pointer to sock_mapping into an uintptr_t and use it as id for the new socket to pass to the backend. The struct will be fully initialized later on connect or bind. sock->sk->sk_send_head is not used for ip sockets: reuse the field to store a pointer to the struct sock_mapping corresponding to the socket. This way, we can easily get the struct sock_mapping from the struct socket. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-10-31 05:40:54 +07:00
static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
{
*req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1);
if (RING_FULL(&bedata->ring) ||
bedata->rsp[*req_id].req_id != PVCALLS_INVALID_ID)
return -EAGAIN;
return 0;
}
static bool pvcalls_front_write_todo(struct sock_mapping *map)
{
struct pvcalls_data_intf *intf = map->active.ring;
RING_IDX cons, prod, size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
int32_t error;
error = intf->out_error;
if (error == -ENOTCONN)
return false;
if (error != 0)
return true;
cons = intf->out_cons;
prod = intf->out_prod;
return !!(size - pvcalls_queued(prod, cons, size));
}
static bool pvcalls_front_read_todo(struct sock_mapping *map)
{
struct pvcalls_data_intf *intf = map->active.ring;
RING_IDX cons, prod;
int32_t error;
cons = intf->in_cons;
prod = intf->in_prod;
error = intf->in_error;
return (error != 0 ||
pvcalls_queued(prod, cons,
XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) != 0);
}
static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
{
xen/pvcalls: implement socket command and handle events Send a PVCALLS_SOCKET command to the backend, use the masked req_prod_pvt as req_id. This way, req_id is guaranteed to be between 0 and PVCALLS_NR_REQ_PER_RING. We already have a slot in the rsp array ready for the response, and there cannot be two outstanding responses with the same req_id. Wait for the response by waiting on the inflight_req waitqueue and check for the req_id field in rsp[req_id]. Use atomic accesses and barriers to read the field. Note that the barriers are simple smp barriers (as opposed to virt barriers) because they are for internal frontend synchronization, not frontend<->backend communication. Once a response is received, clear the corresponding rsp slot by setting req_id to PVCALLS_INVALID_ID. Note that PVCALLS_INVALID_ID is invalid only from the frontend point of view. It is not part of the PVCalls protocol. pvcalls_front_event_handler is in charge of copying responses from the ring to the appropriate rsp slot. It is done by copying the body of the response first, then by copying req_id atomically. After the copies, wake up anybody waiting on waitqueue. socket_lock protects accesses to the ring. Convert the pointer to sock_mapping into an uintptr_t and use it as id for the new socket to pass to the backend. The struct will be fully initialized later on connect or bind. sock->sk->sk_send_head is not used for ip sockets: reuse the field to store a pointer to the struct sock_mapping corresponding to the socket. This way, we can easily get the struct sock_mapping from the struct socket. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-10-31 05:40:54 +07:00
struct xenbus_device *dev = dev_id;
struct pvcalls_bedata *bedata;
struct xen_pvcalls_response *rsp;
uint8_t *src, *dst;
int req_id = 0, more = 0, done = 0;
if (dev == NULL)
return IRQ_HANDLED;
pvcalls_enter();
bedata = dev_get_drvdata(&dev->dev);
if (bedata == NULL) {
pvcalls_exit();
return IRQ_HANDLED;
}
again:
while (RING_HAS_UNCONSUMED_RESPONSES(&bedata->ring)) {
rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons);
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;
}
xen/pvcalls: implement socket command and handle events Send a PVCALLS_SOCKET command to the backend, use the masked req_prod_pvt as req_id. This way, req_id is guaranteed to be between 0 and PVCALLS_NR_REQ_PER_RING. We already have a slot in the rsp array ready for the response, and there cannot be two outstanding responses with the same req_id. Wait for the response by waiting on the inflight_req waitqueue and check for the req_id field in rsp[req_id]. Use atomic accesses and barriers to read the field. Note that the barriers are simple smp barriers (as opposed to virt barriers) because they are for internal frontend synchronization, not frontend<->backend communication. Once a response is received, clear the corresponding rsp slot by setting req_id to PVCALLS_INVALID_ID. Note that PVCALLS_INVALID_ID is invalid only from the frontend point of view. It is not part of the PVCalls protocol. pvcalls_front_event_handler is in charge of copying responses from the ring to the appropriate rsp slot. It is done by copying the body of the response first, then by copying req_id atomically. After the copies, wake up anybody waiting on waitqueue. socket_lock protects accesses to the ring. Convert the pointer to sock_mapping into an uintptr_t and use it as id for the new socket to pass to the backend. The struct will be fully initialized later on connect or bind. sock->sk->sk_send_head is not used for ip sockets: reuse the field to store a pointer to the struct sock_mapping corresponding to the socket. This way, we can easily get the struct sock_mapping from the struct socket. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-10-31 05:40:54 +07:00
done = 1;
bedata->ring.rsp_cons++;
}
RING_FINAL_CHECK_FOR_RESPONSES(&bedata->ring, more);
if (more)
goto again;
if (done)
wake_up(&bedata->inflight_req);
pvcalls_exit();
return IRQ_HANDLED;
}
static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
struct sock_mapping *map)
{
int i;
unbind_from_irqhandler(map->active.irq, map);
spin_lock(&bedata->socket_lock);
if (!list_empty(&map->list))
list_del_init(&map->list);
spin_unlock(&bedata->socket_lock);
for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
gnttab_end_foreign_access(map->active.ring->ref[i], 0, 0);
gnttab_end_foreign_access(map->active.ref, 0, 0);
free_page((unsigned long)map->active.ring);
kfree(map);
}
static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map)
{
struct sock_mapping *map = sock_map;
if (map == NULL)
return IRQ_HANDLED;
wake_up_interruptible(&map->active.inflight_conn_req);
return IRQ_HANDLED;
}
xen/pvcalls: implement socket command and handle events Send a PVCALLS_SOCKET command to the backend, use the masked req_prod_pvt as req_id. This way, req_id is guaranteed to be between 0 and PVCALLS_NR_REQ_PER_RING. We already have a slot in the rsp array ready for the response, and there cannot be two outstanding responses with the same req_id. Wait for the response by waiting on the inflight_req waitqueue and check for the req_id field in rsp[req_id]. Use atomic accesses and barriers to read the field. Note that the barriers are simple smp barriers (as opposed to virt barriers) because they are for internal frontend synchronization, not frontend<->backend communication. Once a response is received, clear the corresponding rsp slot by setting req_id to PVCALLS_INVALID_ID. Note that PVCALLS_INVALID_ID is invalid only from the frontend point of view. It is not part of the PVCalls protocol. pvcalls_front_event_handler is in charge of copying responses from the ring to the appropriate rsp slot. It is done by copying the body of the response first, then by copying req_id atomically. After the copies, wake up anybody waiting on waitqueue. socket_lock protects accesses to the ring. Convert the pointer to sock_mapping into an uintptr_t and use it as id for the new socket to pass to the backend. The struct will be fully initialized later on connect or bind. sock->sk->sk_send_head is not used for ip sockets: reuse the field to store a pointer to the struct sock_mapping corresponding to the socket. This way, we can easily get the struct sock_mapping from the struct socket. Signed-off-by: Stefano Stabellini <stefano@aporeto.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: boris.ostrovsky@oracle.com CC: jgross@suse.com Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2017-10-31 05:40:54 +07:00
int pvcalls_front_socket(struct socket *sock)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map = NULL;
struct xen_pvcalls_request *req;
int notify, req_id, ret;
/*
* PVCalls only supports domain AF_INET,
* type SOCK_STREAM and protocol 0 sockets for now.
*
* Check socket type here, AF_INET and protocol checks are done
* by the caller.
*/
if (sock->type != SOCK_STREAM)
return -EOPNOTSUPP;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -EACCES;
}
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
map = kzalloc(sizeof(*map), GFP_KERNEL);
if (map == NULL) {
pvcalls_exit();
return -ENOMEM;
}
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
kfree(map);
spin_unlock(&bedata->socket_lock);
pvcalls_exit();
return ret;
}
/*
* sock->sk->sk_send_head is not used for ip sockets: reuse the
* field to store a pointer to the struct sock_mapping
* corresponding to the socket. This way, we can easily get the
* struct sock_mapping from the struct socket.
*/
sock->sk->sk_send_head = (void *)map;
list_add_tail(&map->list, &bedata->socket_mappings);
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
req->cmd = PVCALLS_SOCKET;
req->u.socket.id = (uintptr_t) map;
req->u.socket.domain = AF_INET;
req->u.socket.type = SOCK_STREAM;
req->u.socket.protocol = IPPROTO_IP;
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);
wait_event(bedata->inflight_req,
READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
/* read req_id, then the content */
smp_rmb();
ret = bedata->rsp[req_id].ret;
bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
pvcalls_exit();
return ret;
}
static int create_active(struct sock_mapping *map, int *evtchn)
{
void *bytes;
int ret = -ENOMEM, irq = -1, i;
*evtchn = -1;
init_waitqueue_head(&map->active.inflight_conn_req);
map->active.ring = (struct pvcalls_data_intf *)
__get_free_page(GFP_KERNEL | __GFP_ZERO);
if (map->active.ring == NULL)
goto out_error;
map->active.ring->ring_order = PVCALLS_RING_ORDER;
bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
PVCALLS_RING_ORDER);
if (bytes == NULL)
goto out_error;
for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
map->active.ring->ref[i] = gnttab_grant_foreign_access(
pvcalls_front_dev->otherend_id,
pfn_to_gfn(virt_to_pfn(bytes) + i), 0);
map->active.ref = gnttab_grant_foreign_access(
pvcalls_front_dev->otherend_id,
pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0);
map->active.data.in = bytes;
map->active.data.out = bytes +
XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn);
if (ret)
goto out_error;
irq = bind_evtchn_to_irqhandler(*evtchn, pvcalls_front_conn_handler,
0, "pvcalls-frontend", map);
if (irq < 0) {
ret = irq;
goto out_error;
}
map->active.irq = irq;
map->active_socket = true;
mutex_init(&map->active.in_mutex);
mutex_init(&map->active.out_mutex);
return 0;
out_error:
if (*evtchn >= 0)
xenbus_free_evtchn(pvcalls_front_dev, *evtchn);
kfree(map->active.data.in);
kfree(map->active.ring);
return ret;
}
int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
int addr_len, int flags)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map = NULL;
struct xen_pvcalls_request *req;
int notify, req_id, ret, evtchn;
if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
return -EOPNOTSUPP;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -ENOTCONN;
}
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();
return ret;
}
ret = create_active(map, &evtchn);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
pvcalls_exit();
return ret;
}
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
req->cmd = PVCALLS_CONNECT;
req->u.connect.id = (uintptr_t)map;
req->u.connect.len = addr_len;
req->u.connect.flags = flags;
req->u.connect.ref = map->active.ref;
req->u.connect.evtchn = evtchn;
memcpy(req->u.connect.addr, addr, sizeof(*addr));
map->sock = sock;
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);
wait_event(bedata->inflight_req,
READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
/* read req_id, then the content */
smp_rmb();
ret = bedata->rsp[req_id].ret;
bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
pvcalls_exit();
return ret;
}
static int __write_ring(struct pvcalls_data_intf *intf,
struct pvcalls_data *data,
struct iov_iter *msg_iter,
int len)
{
RING_IDX cons, prod, size, masked_prod, masked_cons;
RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
int32_t error;
error = intf->out_error;
if (error < 0)
return error;
cons = intf->out_cons;
prod = intf->out_prod;
/* read indexes before continuing */
virt_mb();
size = pvcalls_queued(prod, cons, array_size);
if (size >= array_size)
return -EINVAL;
if (len > array_size - size)
len = array_size - size;
masked_prod = pvcalls_mask(prod, array_size);
masked_cons = pvcalls_mask(cons, array_size);
if (masked_prod < masked_cons) {
len = copy_from_iter(data->out + masked_prod, len, msg_iter);
} else {
if (len > array_size - masked_prod) {
int ret = copy_from_iter(data->out + masked_prod,
array_size - masked_prod, msg_iter);
if (ret != array_size - masked_prod) {
len = ret;
goto out;
}
len = ret + copy_from_iter(data->out, len - ret, msg_iter);
} else {
len = copy_from_iter(data->out + masked_prod, len, msg_iter);
}
}
out:
/* write to ring before updating pointer */
virt_wmb();
intf->out_prod += len;
return len;
}
int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
size_t len)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map;
int sent, tot_sent = 0;
int count = 0, flags;
flags = msg->msg_flags;
if (flags & (MSG_CONFIRM|MSG_DONTROUTE|MSG_EOR|MSG_OOB))
return -EOPNOTSUPP;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -ENOTCONN;
}
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();
return -EAGAIN;
}
if (len > INT_MAX)
len = INT_MAX;
again:
count++;
sent = __write_ring(map->active.ring,
&map->active.data, &msg->msg_iter,
len);
if (sent > 0) {
len -= sent;
tot_sent += sent;
notify_remote_via_irq(map->active.irq);
}
if (sent >= 0 && len > 0 && count < PVCALLS_FRONT_MAX_SPIN)
goto again;
if (sent < 0)
tot_sent = sent;
mutex_unlock(&map->active.out_mutex);
pvcalls_exit();
return tot_sent;
}
static int __read_ring(struct pvcalls_data_intf *intf,
struct pvcalls_data *data,
struct iov_iter *msg_iter,
size_t len, int flags)
{
RING_IDX cons, prod, size, masked_prod, masked_cons;
RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
int32_t error;
cons = intf->in_cons;
prod = intf->in_prod;
error = intf->in_error;
/* get pointers before reading from the ring */
virt_rmb();
if (error < 0)
return error;
size = pvcalls_queued(prod, cons, array_size);
masked_prod = pvcalls_mask(prod, array_size);
masked_cons = pvcalls_mask(cons, array_size);
if (size == 0)
return 0;
if (len > size)
len = size;
if (masked_prod > masked_cons) {
len = copy_to_iter(data->in + masked_cons, len, msg_iter);
} else {
if (len > (array_size - masked_cons)) {
int ret = copy_to_iter(data->in + masked_cons,
array_size - masked_cons, msg_iter);
if (ret != array_size - masked_cons) {
len = ret;
goto out;
}
len = ret + copy_to_iter(data->in, len - ret, msg_iter);
} else {
len = copy_to_iter(data->in + masked_cons, len, msg_iter);
}
}
out:
/* read data from the ring before increasing the index */
virt_mb();
if (!(flags & MSG_PEEK))
intf->in_cons += len;
return len;
}
int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
int flags)
{
struct pvcalls_bedata *bedata;
int ret;
struct sock_mapping *map;
if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC))
return -EOPNOTSUPP;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -ENOTCONN;
}
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);
while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) {
wait_event_interruptible(map->active.inflight_conn_req,
pvcalls_front_read_todo(map));
}
ret = __read_ring(map->active.ring, &map->active.data,
&msg->msg_iter, len, flags);
if (ret > 0)
notify_remote_via_irq(map->active.irq);
if (ret == 0)
ret = (flags & MSG_DONTWAIT) ? -EAGAIN : 0;
if (ret == -ENOTCONN)
ret = 0;
mutex_unlock(&map->active.in_mutex);
pvcalls_exit();
return ret;
}
int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map = NULL;
struct xen_pvcalls_request *req;
int notify, req_id, ret;
if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM)
return -EOPNOTSUPP;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -ENOTCONN;
}
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();
return ret;
}
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
map->sock = sock;
req->cmd = PVCALLS_BIND;
req->u.bind.id = (uintptr_t)map;
memcpy(req->u.bind.addr, addr, sizeof(*addr));
req->u.bind.len = addr_len;
init_waitqueue_head(&map->passive.inflight_accept_req);
map->active_socket = false;
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);
wait_event(bedata->inflight_req,
READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
/* read req_id, then the content */
smp_rmb();
ret = bedata->rsp[req_id].ret;
bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
map->passive.status = PVCALLS_STATUS_BIND;
pvcalls_exit();
return 0;
}
int pvcalls_front_listen(struct socket *sock, int backlog)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map;
struct xen_pvcalls_request *req;
int notify, req_id, ret;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -ENOTCONN;
}
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();
return -EOPNOTSUPP;
}
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
pvcalls_exit();
return ret;
}
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
req->cmd = PVCALLS_LISTEN;
req->u.listen.id = (uintptr_t) map;
req->u.listen.backlog = backlog;
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);
wait_event(bedata->inflight_req,
READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
/* read req_id, then the content */
smp_rmb();
ret = bedata->rsp[req_id].ret;
bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
map->passive.status = PVCALLS_STATUS_LISTEN;
pvcalls_exit();
return ret;
}
int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map;
struct sock_mapping *map2 = NULL;
struct xen_pvcalls_request *req;
int notify, req_id, ret, evtchn, nonblock;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -ENOTCONN;
}
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();
return -EINVAL;
}
nonblock = flags & SOCK_NONBLOCK;
/*
* Backend only supports 1 inflight accept request, will return
* errors for the others
*/
if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags)) {
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) {
map2 = map->passive.accept_map;
goto received;
}
if (nonblock) {
pvcalls_exit();
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();
return -EINTR;
}
}
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
spin_unlock(&bedata->socket_lock);
pvcalls_exit();
return ret;
}
map2 = kzalloc(sizeof(*map2), GFP_KERNEL);
if (map2 == NULL) {
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
spin_unlock(&bedata->socket_lock);
pvcalls_exit();
return -ENOMEM;
}
ret = create_active(map2, &evtchn);
if (ret < 0) {
kfree(map2);
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
spin_unlock(&bedata->socket_lock);
pvcalls_exit();
return ret;
}
list_add_tail(&map2->list, &bedata->socket_mappings);
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
req->cmd = PVCALLS_ACCEPT;
req->u.accept.id = (uintptr_t) map;
req->u.accept.ref = map2->active.ref;
req->u.accept.id_new = (uintptr_t) map2;
req->u.accept.evtchn = evtchn;
map->passive.accept_map = map2;
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);
/* We could check if we have received a response before returning. */
if (nonblock) {
WRITE_ONCE(map->passive.inflight_req_id, req_id);
pvcalls_exit();
return -EAGAIN;
}
if (wait_event_interruptible(bedata->inflight_req,
READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) {
pvcalls_exit();
return -EINTR;
}
/* read req_id, then the content */
smp_rmb();
received:
map2->sock = newsock;
newsock->sk = kzalloc(sizeof(*newsock->sk), GFP_KERNEL);
if (!newsock->sk) {
bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
map->passive.inflight_req_id = PVCALLS_INVALID_ID;
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
pvcalls_front_free_map(bedata, map2);
pvcalls_exit();
return -ENOMEM;
}
newsock->sk->sk_send_head = (void *)map2;
ret = bedata->rsp[req_id].ret;
bedata->rsp[req_id].req_id = PVCALLS_INVALID_ID;
map->passive.inflight_req_id = PVCALLS_INVALID_ID;
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags);
wake_up(&map->passive.inflight_accept_req);
pvcalls_exit();
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;
}
int pvcalls_front_release(struct socket *sock)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map;
int req_id, notify, ret;
struct xen_pvcalls_request *req;
if (sock->sk == NULL)
return 0;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -EIO;
}
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();
return ret;
}
sock->sk->sk_send_head = NULL;
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
req->cmd = PVCALLS_RELEASE;
req->u.release.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);
wait_event(bedata->inflight_req,
READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
if (map->active_socket) {
/*
* Set in_error and wake up inflight_conn_req to force
* recvmsg waiters to exit.
*/
map->active.ring->in_error = -EBADF;
wake_up_interruptible(&map->active.inflight_conn_req);
/*
* 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.
*/
while (atomic_read(&pvcalls_refcount) > 1)
cpu_relax();
pvcalls_front_free_map(bedata, map);
} else {
spin_lock(&bedata->socket_lock);
list_del(&map->list);
spin_unlock(&bedata->socket_lock);
if (READ_ONCE(map->passive.inflight_req_id) !=
PVCALLS_INVALID_ID) {
pvcalls_front_free_map(bedata,
map->passive.accept_map);
}
kfree(map);
}
WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
pvcalls_exit();
return 0;
}
static const struct xenbus_device_id pvcalls_front_ids[] = {
{ "pvcalls" },
{ "" }
};
static int pvcalls_front_remove(struct xenbus_device *dev)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map = NULL, *n;
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
dev_set_drvdata(&dev->dev, NULL);
pvcalls_front_dev = NULL;
if (bedata->irq >= 0)
unbind_from_irqhandler(bedata->irq, dev);
list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
map->sock->sk->sk_send_head = NULL;
if (map->active_socket) {
map->active.ring->in_error = -EBADF;
wake_up_interruptible(&map->active.inflight_conn_req);
}
}
smp_mb();
while (atomic_read(&pvcalls_refcount) > 0)
cpu_relax();
list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
if (map->active_socket) {
/* No need to lock, refcount is 0 */
pvcalls_front_free_map(bedata, map);
} else {
list_del(&map->list);
kfree(map);
}
}
if (bedata->ref >= 0)
gnttab_end_foreign_access(bedata->ref, 0, 0);
kfree(bedata->ring.sring);
kfree(bedata);
xenbus_switch_state(dev, XenbusStateClosed);
return 0;
}
static int pvcalls_front_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
int ret = -ENOMEM, evtchn, i;
unsigned int max_page_order, function_calls, len;
char *versions;
grant_ref_t gref_head = 0;
struct xenbus_transaction xbt;
struct pvcalls_bedata *bedata = NULL;
struct xen_pvcalls_sring *sring;
if (pvcalls_front_dev != NULL) {
dev_err(&dev->dev, "only one PV Calls connection supported\n");
return -EINVAL;
}
versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
if (!len)
return -EINVAL;
if (strcmp(versions, "1")) {
kfree(versions);
return -EINVAL;
}
kfree(versions);
max_page_order = xenbus_read_unsigned(dev->otherend,
"max-page-order", 0);
if (max_page_order < PVCALLS_RING_ORDER)
return -ENODEV;
function_calls = xenbus_read_unsigned(dev->otherend,
"function-calls", 0);
/* See XENBUS_FUNCTIONS_CALLS in pvcalls.h */
if (function_calls != 1)
return -ENODEV;
pr_info("%s max-page-order is %u\n", __func__, max_page_order);
bedata = kzalloc(sizeof(struct pvcalls_bedata), GFP_KERNEL);
if (!bedata)
return -ENOMEM;
dev_set_drvdata(&dev->dev, bedata);
pvcalls_front_dev = dev;
init_waitqueue_head(&bedata->inflight_req);
INIT_LIST_HEAD(&bedata->socket_mappings);
spin_lock_init(&bedata->socket_lock);
bedata->irq = -1;
bedata->ref = -1;
for (i = 0; i < PVCALLS_NR_RSP_PER_RING; i++)
bedata->rsp[i].req_id = PVCALLS_INVALID_ID;
sring = (struct xen_pvcalls_sring *) __get_free_page(GFP_KERNEL |
__GFP_ZERO);
if (!sring)
goto error;
SHARED_RING_INIT(sring);
FRONT_RING_INIT(&bedata->ring, sring, XEN_PAGE_SIZE);
ret = xenbus_alloc_evtchn(dev, &evtchn);
if (ret)
goto error;
bedata->irq = bind_evtchn_to_irqhandler(evtchn,
pvcalls_front_event_handler,
0, "pvcalls-frontend", dev);
if (bedata->irq < 0) {
ret = bedata->irq;
goto error;
}
ret = gnttab_alloc_grant_references(1, &gref_head);
if (ret < 0)
goto error;
ret = gnttab_claim_grant_reference(&gref_head);
if (ret < 0)
goto error;
bedata->ref = ret;
gnttab_grant_foreign_access_ref(bedata->ref, dev->otherend_id,
virt_to_gfn((void *)sring), 0);
again:
ret = xenbus_transaction_start(&xbt);
if (ret) {
xenbus_dev_fatal(dev, ret, "starting transaction");
goto error;
}
ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
if (ret)
goto error_xenbus;
ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", bedata->ref);
if (ret)
goto error_xenbus;
ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
evtchn);
if (ret)
goto error_xenbus;
ret = xenbus_transaction_end(xbt, 0);
if (ret) {
if (ret == -EAGAIN)
goto again;
xenbus_dev_fatal(dev, ret, "completing transaction");
goto error;
}
xenbus_switch_state(dev, XenbusStateInitialised);
return 0;
error_xenbus:
xenbus_transaction_end(xbt, 1);
xenbus_dev_fatal(dev, ret, "writing xenstore");
error:
pvcalls_front_remove(dev);
return ret;
}
static void pvcalls_front_changed(struct xenbus_device *dev,
enum xenbus_state backend_state)
{
switch (backend_state) {
case XenbusStateReconfiguring:
case XenbusStateReconfigured:
case XenbusStateInitialising:
case XenbusStateInitialised:
case XenbusStateUnknown:
break;
case XenbusStateInitWait:
break;
case XenbusStateConnected:
xenbus_switch_state(dev, XenbusStateConnected);
break;
case XenbusStateClosed:
if (dev->state == XenbusStateClosed)
break;
/* Missed the backend's CLOSING state */
/* fall through */
case XenbusStateClosing:
xenbus_frontend_closed(dev);
break;
}
}
static struct xenbus_driver pvcalls_front_driver = {
.ids = pvcalls_front_ids,
.probe = pvcalls_front_probe,
.remove = pvcalls_front_remove,
.otherend_changed = pvcalls_front_changed,
};
static int __init pvcalls_frontend_init(void)
{
if (!xen_domain())
return -ENODEV;
pr_info("Initialising Xen pvcalls frontend driver\n");
return xenbus_register_frontend(&pvcalls_front_driver);
}
module_init(pvcalls_frontend_init);
MODULE_DESCRIPTION("Xen PV Calls frontend driver");
MODULE_AUTHOR("Stefano Stabellini <sstabellini@kernel.org>");
MODULE_LICENSE("GPL");