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![Gustavo A. R. Silva](/assets/img/avatar_default.png)
pdev_nr and rhport can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/usb/usbip/vhci_sysfs.c:238 detach_store() warn: potential spectre issue 'vhcis' drivers/usb/usbip/vhci_sysfs.c:328 attach_store() warn: potential spectre issue 'vhcis' drivers/usb/usbip/vhci_sysfs.c:338 attach_store() warn: potential spectre issue 'vhci->vhci_hcd_ss->vdev' drivers/usb/usbip/vhci_sysfs.c:340 attach_store() warn: potential spectre issue 'vhci->vhci_hcd_hs->vdev' Fix this by sanitizing pdev_nr and rhport before using them to index vhcis and vhci->vhci_hcd_ss->vdev respectively. Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Acked-by: Shuah Khan (Samsung OSG) <shuah@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
477 lines
11 KiB
C
477 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2003-2008 Takahiro Hirofuchi
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* Copyright (C) 2015-2016 Nobuo Iwata
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*/
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#include <linux/kthread.h>
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#include <linux/file.h>
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#include <linux/net.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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/* Hardening for Spectre-v1 */
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#include <linux/nospec.h>
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#include "usbip_common.h"
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#include "vhci.h"
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/* TODO: refine locking ?*/
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/*
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* output example:
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* hub port sta spd dev sockfd local_busid
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* hs 0000 004 000 00000000 000003 1-2.3
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* ................................................
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* ss 0008 004 000 00000000 000004 2-3.4
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* ................................................
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*
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* Output includes socket fd instead of socket pointer address to avoid
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* leaking kernel memory address in:
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* /sys/devices/platform/vhci_hcd.0/status and in debug output.
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* The socket pointer address is not used at the moment and it was made
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* visible as a convenient way to find IP address from socket pointer
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* address by looking up /proc/net/{tcp,tcp6}. As this opens a security
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* hole, the change is made to use sockfd instead.
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*
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*/
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static void port_show_vhci(char **out, int hub, int port, struct vhci_device *vdev)
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{
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if (hub == HUB_SPEED_HIGH)
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*out += sprintf(*out, "hs %04u %03u ",
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port, vdev->ud.status);
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else /* hub == HUB_SPEED_SUPER */
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*out += sprintf(*out, "ss %04u %03u ",
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port, vdev->ud.status);
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if (vdev->ud.status == VDEV_ST_USED) {
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*out += sprintf(*out, "%03u %08x ",
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vdev->speed, vdev->devid);
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*out += sprintf(*out, "%06u %s",
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vdev->ud.sockfd,
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dev_name(&vdev->udev->dev));
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} else {
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*out += sprintf(*out, "000 00000000 ");
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*out += sprintf(*out, "000000 0-0");
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}
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*out += sprintf(*out, "\n");
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}
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/* Sysfs entry to show port status */
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static ssize_t status_show_vhci(int pdev_nr, char *out)
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{
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struct platform_device *pdev = vhcis[pdev_nr].pdev;
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struct vhci *vhci;
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struct usb_hcd *hcd;
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struct vhci_hcd *vhci_hcd;
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char *s = out;
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int i;
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unsigned long flags;
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if (!pdev || !out) {
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usbip_dbg_vhci_sysfs("show status error\n");
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return 0;
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}
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hcd = platform_get_drvdata(pdev);
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vhci_hcd = hcd_to_vhci_hcd(hcd);
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vhci = vhci_hcd->vhci;
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spin_lock_irqsave(&vhci->lock, flags);
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for (i = 0; i < VHCI_HC_PORTS; i++) {
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struct vhci_device *vdev = &vhci->vhci_hcd_hs->vdev[i];
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spin_lock(&vdev->ud.lock);
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port_show_vhci(&out, HUB_SPEED_HIGH,
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pdev_nr * VHCI_PORTS + i, vdev);
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spin_unlock(&vdev->ud.lock);
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}
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for (i = 0; i < VHCI_HC_PORTS; i++) {
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struct vhci_device *vdev = &vhci->vhci_hcd_ss->vdev[i];
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spin_lock(&vdev->ud.lock);
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port_show_vhci(&out, HUB_SPEED_SUPER,
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pdev_nr * VHCI_PORTS + VHCI_HC_PORTS + i, vdev);
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spin_unlock(&vdev->ud.lock);
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}
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spin_unlock_irqrestore(&vhci->lock, flags);
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return out - s;
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}
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static ssize_t status_show_not_ready(int pdev_nr, char *out)
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{
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char *s = out;
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int i = 0;
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for (i = 0; i < VHCI_HC_PORTS; i++) {
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out += sprintf(out, "hs %04u %03u ",
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(pdev_nr * VHCI_PORTS) + i,
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VDEV_ST_NOTASSIGNED);
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out += sprintf(out, "000 00000000 0000000000000000 0-0");
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out += sprintf(out, "\n");
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}
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for (i = 0; i < VHCI_HC_PORTS; i++) {
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out += sprintf(out, "ss %04u %03u ",
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(pdev_nr * VHCI_PORTS) + VHCI_HC_PORTS + i,
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VDEV_ST_NOTASSIGNED);
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out += sprintf(out, "000 00000000 0000000000000000 0-0");
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out += sprintf(out, "\n");
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}
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return out - s;
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}
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static int status_name_to_id(const char *name)
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{
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char *c;
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long val;
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int ret;
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c = strchr(name, '.');
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if (c == NULL)
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return 0;
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ret = kstrtol(c+1, 10, &val);
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if (ret < 0)
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return ret;
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return val;
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}
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static ssize_t status_show(struct device *dev,
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struct device_attribute *attr, char *out)
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{
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char *s = out;
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int pdev_nr;
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out += sprintf(out,
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"hub port sta spd dev sockfd local_busid\n");
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pdev_nr = status_name_to_id(attr->attr.name);
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if (pdev_nr < 0)
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out += status_show_not_ready(pdev_nr, out);
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else
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out += status_show_vhci(pdev_nr, out);
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return out - s;
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}
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static ssize_t nports_show(struct device *dev, struct device_attribute *attr,
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char *out)
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{
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char *s = out;
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/*
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* Half the ports are for SPEED_HIGH and half for SPEED_SUPER,
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* thus the * 2.
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*/
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out += sprintf(out, "%d\n", VHCI_PORTS * vhci_num_controllers);
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return out - s;
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}
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static DEVICE_ATTR_RO(nports);
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/* Sysfs entry to shutdown a virtual connection */
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static int vhci_port_disconnect(struct vhci_hcd *vhci_hcd, __u32 rhport)
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{
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struct vhci_device *vdev = &vhci_hcd->vdev[rhport];
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struct vhci *vhci = vhci_hcd->vhci;
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unsigned long flags;
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usbip_dbg_vhci_sysfs("enter\n");
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/* lock */
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spin_lock_irqsave(&vhci->lock, flags);
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spin_lock(&vdev->ud.lock);
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if (vdev->ud.status == VDEV_ST_NULL) {
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pr_err("not connected %d\n", vdev->ud.status);
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/* unlock */
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spin_unlock(&vdev->ud.lock);
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spin_unlock_irqrestore(&vhci->lock, flags);
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return -EINVAL;
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}
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/* unlock */
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spin_unlock(&vdev->ud.lock);
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spin_unlock_irqrestore(&vhci->lock, flags);
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usbip_event_add(&vdev->ud, VDEV_EVENT_DOWN);
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return 0;
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}
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static int valid_port(__u32 *pdev_nr, __u32 *rhport)
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{
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if (*pdev_nr >= vhci_num_controllers) {
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pr_err("pdev %u\n", *pdev_nr);
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return 0;
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}
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*pdev_nr = array_index_nospec(*pdev_nr, vhci_num_controllers);
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if (*rhport >= VHCI_HC_PORTS) {
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pr_err("rhport %u\n", *rhport);
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return 0;
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}
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*rhport = array_index_nospec(*rhport, VHCI_HC_PORTS);
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return 1;
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}
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static ssize_t detach_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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__u32 port = 0, pdev_nr = 0, rhport = 0;
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struct usb_hcd *hcd;
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struct vhci_hcd *vhci_hcd;
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int ret;
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if (kstrtoint(buf, 10, &port) < 0)
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return -EINVAL;
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pdev_nr = port_to_pdev_nr(port);
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rhport = port_to_rhport(port);
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if (!valid_port(&pdev_nr, &rhport))
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return -EINVAL;
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hcd = platform_get_drvdata(vhcis[pdev_nr].pdev);
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if (hcd == NULL) {
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dev_err(dev, "port is not ready %u\n", port);
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return -EAGAIN;
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}
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usbip_dbg_vhci_sysfs("rhport %d\n", rhport);
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if ((port / VHCI_HC_PORTS) % 2)
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vhci_hcd = hcd_to_vhci_hcd(hcd)->vhci->vhci_hcd_ss;
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else
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vhci_hcd = hcd_to_vhci_hcd(hcd)->vhci->vhci_hcd_hs;
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ret = vhci_port_disconnect(vhci_hcd, rhport);
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if (ret < 0)
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return -EINVAL;
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usbip_dbg_vhci_sysfs("Leave\n");
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return count;
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}
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static DEVICE_ATTR_WO(detach);
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static int valid_args(__u32 *pdev_nr, __u32 *rhport,
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enum usb_device_speed speed)
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{
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if (!valid_port(pdev_nr, rhport)) {
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return 0;
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}
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switch (speed) {
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case USB_SPEED_LOW:
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case USB_SPEED_FULL:
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case USB_SPEED_HIGH:
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case USB_SPEED_WIRELESS:
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case USB_SPEED_SUPER:
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break;
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default:
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pr_err("Failed attach request for unsupported USB speed: %s\n",
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usb_speed_string(speed));
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return 0;
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}
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return 1;
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}
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/* Sysfs entry to establish a virtual connection */
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/*
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* To start a new USB/IP attachment, a userland program needs to setup a TCP
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* connection and then write its socket descriptor with remote device
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* information into this sysfs file.
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*
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* A remote device is virtually attached to the root-hub port of @rhport with
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* @speed. @devid is embedded into a request to specify the remote device in a
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* server host.
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*
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* write() returns 0 on success, else negative errno.
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*/
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static ssize_t attach_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct socket *socket;
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int sockfd = 0;
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__u32 port = 0, pdev_nr = 0, rhport = 0, devid = 0, speed = 0;
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struct usb_hcd *hcd;
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struct vhci_hcd *vhci_hcd;
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struct vhci_device *vdev;
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struct vhci *vhci;
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int err;
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unsigned long flags;
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/*
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* @rhport: port number of vhci_hcd
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* @sockfd: socket descriptor of an established TCP connection
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* @devid: unique device identifier in a remote host
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* @speed: usb device speed in a remote host
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*/
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if (sscanf(buf, "%u %u %u %u", &port, &sockfd, &devid, &speed) != 4)
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return -EINVAL;
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pdev_nr = port_to_pdev_nr(port);
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rhport = port_to_rhport(port);
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usbip_dbg_vhci_sysfs("port(%u) pdev(%d) rhport(%u)\n",
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port, pdev_nr, rhport);
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usbip_dbg_vhci_sysfs("sockfd(%u) devid(%u) speed(%u)\n",
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sockfd, devid, speed);
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/* check received parameters */
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if (!valid_args(&pdev_nr, &rhport, speed))
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return -EINVAL;
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hcd = platform_get_drvdata(vhcis[pdev_nr].pdev);
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if (hcd == NULL) {
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dev_err(dev, "port %d is not ready\n", port);
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return -EAGAIN;
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}
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vhci_hcd = hcd_to_vhci_hcd(hcd);
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vhci = vhci_hcd->vhci;
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if (speed == USB_SPEED_SUPER)
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vdev = &vhci->vhci_hcd_ss->vdev[rhport];
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else
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vdev = &vhci->vhci_hcd_hs->vdev[rhport];
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/* Extract socket from fd. */
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socket = sockfd_lookup(sockfd, &err);
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if (!socket)
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return -EINVAL;
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/* now need lock until setting vdev status as used */
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/* begin a lock */
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spin_lock_irqsave(&vhci->lock, flags);
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spin_lock(&vdev->ud.lock);
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if (vdev->ud.status != VDEV_ST_NULL) {
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/* end of the lock */
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spin_unlock(&vdev->ud.lock);
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spin_unlock_irqrestore(&vhci->lock, flags);
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sockfd_put(socket);
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dev_err(dev, "port %d already used\n", rhport);
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/*
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* Will be retried from userspace
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* if there's another free port.
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*/
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return -EBUSY;
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}
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dev_info(dev, "pdev(%u) rhport(%u) sockfd(%d)\n",
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pdev_nr, rhport, sockfd);
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dev_info(dev, "devid(%u) speed(%u) speed_str(%s)\n",
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devid, speed, usb_speed_string(speed));
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vdev->devid = devid;
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vdev->speed = speed;
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vdev->ud.sockfd = sockfd;
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vdev->ud.tcp_socket = socket;
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vdev->ud.status = VDEV_ST_NOTASSIGNED;
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spin_unlock(&vdev->ud.lock);
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spin_unlock_irqrestore(&vhci->lock, flags);
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/* end the lock */
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vdev->ud.tcp_rx = kthread_get_run(vhci_rx_loop, &vdev->ud, "vhci_rx");
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vdev->ud.tcp_tx = kthread_get_run(vhci_tx_loop, &vdev->ud, "vhci_tx");
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rh_port_connect(vdev, speed);
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return count;
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}
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static DEVICE_ATTR_WO(attach);
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#define MAX_STATUS_NAME 16
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struct status_attr {
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struct device_attribute attr;
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char name[MAX_STATUS_NAME+1];
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};
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static struct status_attr *status_attrs;
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static void set_status_attr(int id)
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{
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struct status_attr *status;
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status = status_attrs + id;
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if (id == 0)
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strcpy(status->name, "status");
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else
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snprintf(status->name, MAX_STATUS_NAME+1, "status.%d", id);
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status->attr.attr.name = status->name;
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status->attr.attr.mode = S_IRUGO;
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status->attr.show = status_show;
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sysfs_attr_init(&status->attr.attr);
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}
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static int init_status_attrs(void)
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{
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int id;
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status_attrs = kcalloc(vhci_num_controllers, sizeof(struct status_attr),
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GFP_KERNEL);
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if (status_attrs == NULL)
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return -ENOMEM;
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for (id = 0; id < vhci_num_controllers; id++)
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set_status_attr(id);
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return 0;
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}
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static void finish_status_attrs(void)
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{
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kfree(status_attrs);
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}
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struct attribute_group vhci_attr_group = {
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.attrs = NULL,
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};
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int vhci_init_attr_group(void)
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{
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struct attribute **attrs;
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int ret, i;
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attrs = kcalloc((vhci_num_controllers + 5), sizeof(struct attribute *),
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GFP_KERNEL);
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if (attrs == NULL)
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return -ENOMEM;
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ret = init_status_attrs();
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if (ret) {
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kfree(attrs);
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return ret;
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}
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*attrs = &dev_attr_nports.attr;
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*(attrs + 1) = &dev_attr_detach.attr;
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*(attrs + 2) = &dev_attr_attach.attr;
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*(attrs + 3) = &dev_attr_usbip_debug.attr;
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for (i = 0; i < vhci_num_controllers; i++)
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*(attrs + i + 4) = &((status_attrs + i)->attr.attr);
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vhci_attr_group.attrs = attrs;
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return 0;
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}
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void vhci_finish_attr_group(void)
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{
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finish_status_attrs();
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kfree(vhci_attr_group.attrs);
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}
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