I entered a patch which adds "exclusive_access" lock into 2.4.29, to fix
devices which cannot handle simultaneous accesses. This caused a regression
with European ADSL modems. An ioctl USBDEVFS_REAPURB allows a process to enter
the kernel and wait for USB I/O to finish. Naturally, this should not take
exclusive_access, or nothing will ever finish.
This patch is essentially the patch by Sergey Vlasov with my additions
a) to allow ENOTTY returned without taking a lock and b) to filter ENOIOCTLCMD,
which is improper to leak to userspace.
diff -urpN -X dontdiff linux-2.4.30-pre1/drivers/usb/devio.c
linux-2.4.30-pre1-usb/drivers/usb/devio.c
--- linux-2.4.30-pre1/drivers/usb/devio.c 2004-11-22 23:04:18.000000000
-0800
+++ linux-2.4.30-pre1-usb/drivers/usb/devio.c 2005-02-10 11:18:08.000000000
-0800
@@ -1132,6 +1132,8 @@ static int proc_ioctl (struct dev_state
/* ifno might usefully be passed ... */
retval = driver->ioctl (ps->dev, ctrl.ioctl_code, buf);
/* size = min_t(int, size, retval)? */
+ if (retval == -ENOIOCTLCMD)
+ retval = -ENOTTY;
}
}
@@ -1146,24 +1148,10 @@ static int proc_ioctl (struct dev_state
return retval;
}
-static int usbdev_ioctl(struct inode *inode, struct file *file, unsigned int
cmd, unsigned long arg)
+static int usbdev_ioctl_exclusive(struct dev_state *ps, struct inode *inode,
+ unsigned int cmd, unsigned long arg)
{
- struct dev_state *ps = (struct dev_state *)file->private_data;
- int ret = -ENOIOCTLCMD;
-
- if (!(file->f_mode & FMODE_WRITE))
- return -EPERM;
- down_read(&ps->devsem);
- if (!ps->dev) {
- up_read(&ps->devsem);
- return -ENODEV;
- }
-
- /*
- * grab device's exclusive_access mutex to prevent its driver from
- * using this device while it is being accessed by us.
- */
- down(&ps->dev->exclusive_access);
+ int ret;
switch (cmd) {
case USBDEVFS_CONTROL:
@@ -1194,14 +1182,6 @@ static int usbdev_ioctl(struct inode *in
inode->i_mtime = CURRENT_TIME;
break;
- case USBDEVFS_GETDRIVER:
- ret = proc_getdriver(ps, (void *)arg);
- break;
-
- case USBDEVFS_CONNECTINFO:
- ret = proc_connectinfo(ps, (void *)arg);
- break;
-
case USBDEVFS_SETINTERFACE:
ret = proc_setintf(ps, (void *)arg);
break;
@@ -1220,6 +1200,53 @@ static int usbdev_ioctl(struct inode *in
ret = proc_unlinkurb(ps, (void *)arg);
break;
+ case USBDEVFS_CLAIMINTERFACE:
+ ret = proc_claiminterface(ps, (void *)arg);
+ break;
+
+ case USBDEVFS_RELEASEINTERFACE:
+ ret = proc_releaseinterface(ps, (void *)arg);
+ break;
+
+ case USBDEVFS_IOCTL:
+ ret = proc_ioctl(ps, (void *) arg);
+ break;
+
+ default:
+ ret = -ENOTTY;
+ }
+ return ret;
+}
+
+static int usbdev_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct dev_state *ps = file->private_data;
+ int ret;
+
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EPERM;
+ down_read(&ps->devsem);
+ if (!ps->dev) {
+ up_read(&ps->devsem);
+ return -ENODEV;
+ }
+
+ /*
+ * Some ioctls don't touch the device and can be called without
+ * grabbing its exclusive_access mutex; they are handled in this
+ * switch. Other ioctls which need exclusive_access are handled in
+ * usbdev_ioctl_exclusive().
+ */
+ switch (cmd) {
+ case USBDEVFS_GETDRIVER:
+ ret = proc_getdriver(ps, (void *)arg);
+ break;
+
+ case USBDEVFS_CONNECTINFO:
+ ret = proc_connectinfo(ps, (void *)arg);
+ break;
+
case USBDEVFS_REAPURB:
ret = proc_reapurb(ps, (void *)arg);
break;
@@ -1232,19 +1259,28 @@ static int usbdev_ioctl(struct inode *in
ret = proc_disconnectsignal(ps, (void *)arg);
break;
+ case USBDEVFS_CONTROL:
+ case USBDEVFS_BULK:
+ case USBDEVFS_RESETEP:
+ case USBDEVFS_RESET:
+ case USBDEVFS_CLEAR_HALT:
+ case USBDEVFS_SETINTERFACE:
+ case USBDEVFS_SETCONFIGURATION:
+ case USBDEVFS_SUBMITURB:
+ case USBDEVFS_DISCARDURB:
case USBDEVFS_CLAIMINTERFACE:
- ret = proc_claiminterface(ps, (void *)arg);
- break;
-
case USBDEVFS_RELEASEINTERFACE:
- ret = proc_releaseinterface(ps, (void *)arg);
- break;
-
case USBDEVFS_IOCTL:
- ret = proc_ioctl(ps, (void *) arg);
+ ret = -ERESTARTSYS;
+ if (down_interruptible(&ps->dev->exclusive_access) == 0) {
+ ret = usbdev_ioctl_exclusive(ps, inode, cmd, arg);
+ up(&ps->dev->exclusive_access);
+ }
break;
+
+ default:
+ ret = -ENOTTY;
}
- up(&ps->dev->exclusive_access);
up_read(&ps->devsem);
if (ret >= 0)
inode->i_atime = CURRENT_TIME;
-
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