Hello.
On 01/14/2013 11:36 PM, Sergei Shtylyov wrote:
> Serialize usb-storage operations with usbfs and 'cat /proc/bus/usb/devices',
> so that they cannot disturb storage by seemingly harmless control reads.
> This patch was adapted from 2.4.28 patch by Pete Zaitcev -- which I even had to
> reconstruct as I have never found it in its final form. That patch dates back
> to 2004 and it unfortunately wasn't applied to 2.6 branch in the same form back
> then (it was applied in another form and then immediately reverted). Despite 8+
> years passing from that moment, the vendors didn't stop producing USB devices
> that require this patch. Two recent examples are SanDisk Cruzer Slice 8GB and
> Kingston DataTraveller 100 G2 32GB. In the latter case, even the enumeration
> fails as the INQUIRY command takes 2.8 seconds to finish, so 'udev' also comes
> into action with its control requests, with neither completing normally.
> Signed-off-by: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> This patch is atop of 'usb-linus' branch of Greg's tree...
> drivers/usb/core/devices.c | 13 +++++++++++--
> drivers/usb/core/devio.c | 7 +++++++
> drivers/usb/core/usb.c | 2 ++
> drivers/usb/storage/transport.c | 11 +++++++++++
> include/linux/usb.h | 4 ++++
> 5 files changed, 35 insertions(+), 2 deletions(-)
> Index: usb/drivers/usb/core/devio.c
> ===================================================================
> --- usb.orig/drivers/usb/core/devio.c
> +++ usb/drivers/usb/core/devio.c
> @@ -1983,6 +1983,12 @@ static long usbdev_do_ioctl(struct file
> return -ENODEV;
> }
>
> + /*
> + * Grab device's exclusive_access mutex to prevent its driver from
> + * using this device while it is being accessed by us.
> + */
> + mutex_lock(&dev->exclusive_access);
> +
> switch (cmd) {
> case USBDEVFS_CONTROL:
> snoop(&dev->dev, "%s: CONTROL\n", __func__);
> @@ -2138,6 +2144,7 @@ static long usbdev_do_ioctl(struct file
> ret = proc_disconnect_claim(ps, p);
> break;
> }
> + mutex_unlock(&dev->exclusive_access);
> usb_unlock_device(dev);
> if (ret >= 0)
> inode->i_atime = CURRENT_TIME;
Forgot to mention the side effect of the patch: one can't submit read and
write URB simultaneously via USBDEVFS_BULK ioctl(). That has been dealt in 2.4
by later patch by Pete, which I can try to port if needed.
WBR, Sergei
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