mirror_ubuntu-kernels/tools/usb/usbip/src/usbip_attach.c
Nobuo Iwata a38711a88b usbip: auto retry for concurrent attach
This patch adds recovery from false busy state on concurrent attach
operation.

The procedure of attach operation is as below.
1) Find an unused port in /sys/devices/platform/vhci_hcd/status.
(userspace)
2) Request attach found port to driver through
/sys/devices/platform/vhci_hcd/attach. (userspace)
3) Lock table, reserve requested port and unlock table. (vhci driver)

Attaching more than one remote devices concurrently, same unused port
number will be found in step-1. Then one request will succeed and
others will fail even though there are some unused ports.

With this patch, driver returns EBUSY when requested port has already
been used. In this case, attach command retries from step-1: finding
another unused port. If there's no unused port, the attach operation
will fail in step-1. Otherwise it retries automatically using another
unused port.

vhci-hcd's interface (only errno) is changed as following.

Current	errno	New errno	Condition
EINVAL		same as left	specified port number is in invalid
				range
EAGAIN		same as left	platform_get_drvdata() failed
EINVAL		same as left	specified socket fd is not valid
EINVAL		EBUSY		specified port status is not free

The errno EBUSY was not used in userspace
src/usbip_attach.c:import_device(). It is needed to distinguish the
condition to be able to retry from other unrecoverable errors.

It is possible to avoid this failure by introducing userspace exclusive
control. But it's exaggerated for this special condition. The locking
itself has done in driver.
As an alternate solution, userspace doesn't specify port number, driver
searches unused port and it returns port number to the userspace. With
this solution, the interface is much different than this patch.

Signed-off-by: Nobuo Iwata <nobuo.iwata@fujixerox.co.jp>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-08-31 18:08:45 +02:00

256 lines
5.2 KiB
C

/*
* Copyright (C) 2011 matt mooney <mfm@muteddisk.com>
* 2005-2007 Takahiro Hirofuchi
* Copyright (C) 2015-2016 Samsung Electronics
* Igor Kotrasinski <i.kotrasinsk@samsung.com>
* Krzysztof Opasiak <k.opasiak@samsung.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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <sys/stat.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <getopt.h>
#include <unistd.h>
#include <errno.h>
#include "vhci_driver.h"
#include "usbip_common.h"
#include "usbip_network.h"
#include "usbip.h"
static const char usbip_attach_usage_string[] =
"usbip attach <args>\n"
" -r, --remote=<host> The machine with exported USB devices\n"
" -b, --busid=<busid> Busid of the device on <host>\n"
" -d, --device=<devid> Id of the virtual UDC on <host>\n";
void usbip_attach_usage(void)
{
printf("usage: %s", usbip_attach_usage_string);
}
#define MAX_BUFF 100
static int record_connection(char *host, char *port, char *busid, int rhport)
{
int fd;
char path[PATH_MAX+1];
char buff[MAX_BUFF+1];
int ret;
ret = mkdir(VHCI_STATE_PATH, 0700);
if (ret < 0) {
/* if VHCI_STATE_PATH exists, then it better be a directory */
if (errno == EEXIST) {
struct stat s;
ret = stat(VHCI_STATE_PATH, &s);
if (ret < 0)
return -1;
if (!(s.st_mode & S_IFDIR))
return -1;
} else
return -1;
}
snprintf(path, PATH_MAX, VHCI_STATE_PATH"/port%d", rhport);
fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU);
if (fd < 0)
return -1;
snprintf(buff, MAX_BUFF, "%s %s %s\n",
host, port, busid);
ret = write(fd, buff, strlen(buff));
if (ret != (ssize_t) strlen(buff)) {
close(fd);
return -1;
}
close(fd);
return 0;
}
static int import_device(int sockfd, struct usbip_usb_device *udev)
{
int rc;
int port;
uint32_t speed = udev->speed;
rc = usbip_vhci_driver_open();
if (rc < 0) {
err("open vhci_driver");
goto err_out;
}
do {
port = usbip_vhci_get_free_port(speed);
if (port < 0) {
err("no free port");
goto err_driver_close;
}
dbg("got free port %d", port);
rc = usbip_vhci_attach_device(port, sockfd, udev->busnum,
udev->devnum, udev->speed);
if (rc < 0 && errno != EBUSY) {
err("import device");
goto err_driver_close;
}
} while (rc < 0);
usbip_vhci_driver_close();
return port;
err_driver_close:
usbip_vhci_driver_close();
err_out:
return -1;
}
static int query_import_device(int sockfd, char *busid)
{
int rc;
struct op_import_request request;
struct op_import_reply reply;
uint16_t code = OP_REP_IMPORT;
memset(&request, 0, sizeof(request));
memset(&reply, 0, sizeof(reply));
/* send a request */
rc = usbip_net_send_op_common(sockfd, OP_REQ_IMPORT, 0);
if (rc < 0) {
err("send op_common");
return -1;
}
strncpy(request.busid, busid, SYSFS_BUS_ID_SIZE-1);
PACK_OP_IMPORT_REQUEST(0, &request);
rc = usbip_net_send(sockfd, (void *) &request, sizeof(request));
if (rc < 0) {
err("send op_import_request");
return -1;
}
/* receive a reply */
rc = usbip_net_recv_op_common(sockfd, &code);
if (rc < 0) {
err("recv op_common");
return -1;
}
rc = usbip_net_recv(sockfd, (void *) &reply, sizeof(reply));
if (rc < 0) {
err("recv op_import_reply");
return -1;
}
PACK_OP_IMPORT_REPLY(0, &reply);
/* check the reply */
if (strncmp(reply.udev.busid, busid, SYSFS_BUS_ID_SIZE)) {
err("recv different busid %s", reply.udev.busid);
return -1;
}
/* import a device */
return import_device(sockfd, &reply.udev);
}
static int attach_device(char *host, char *busid)
{
int sockfd;
int rc;
int rhport;
sockfd = usbip_net_tcp_connect(host, usbip_port_string);
if (sockfd < 0) {
err("tcp connect");
return -1;
}
rhport = query_import_device(sockfd, busid);
if (rhport < 0) {
err("query");
return -1;
}
close(sockfd);
rc = record_connection(host, usbip_port_string, busid, rhport);
if (rc < 0) {
err("record connection");
return -1;
}
return 0;
}
int usbip_attach(int argc, char *argv[])
{
static const struct option opts[] = {
{ "remote", required_argument, NULL, 'r' },
{ "busid", required_argument, NULL, 'b' },
{ "device", required_argument, NULL, 'd' },
{ NULL, 0, NULL, 0 }
};
char *host = NULL;
char *busid = NULL;
int opt;
int ret = -1;
for (;;) {
opt = getopt_long(argc, argv, "d:r:b:", opts, NULL);
if (opt == -1)
break;
switch (opt) {
case 'r':
host = optarg;
break;
case 'd':
case 'b':
busid = optarg;
break;
default:
goto err_out;
}
}
if (!host || !busid)
goto err_out;
ret = attach_device(host, busid);
goto out;
err_out:
usbip_attach_usage();
out:
return ret;
}