Re: Bug with USB proc_bulk in 2.4 kernel

From: Willy Tarreau
Date: Thu Aug 03 2006 - 02:35:36 EST

On Wed, Aug 02, 2006 at 11:00:58PM -0700, Pete Zaitcev wrote:
> Replace the semaphore exclusive_access with an open-coded lock for
> the special use. The lock can be taken for: read, write, and both.
> This way, two bulk URBs can be submitted simultaneously with ioctl
> USBDEVFS_BULK: one read and one write. Such access was possible
> before 2.4.28.
> Signed-off-By: Pete Zaitcev <zaitcev@xxxxxxxxxx>
> ---
> The semaphore was introduced in 2.4.28 for the purpose of exclusion
> between access from device.c (cat /proc/bus/usb/devices), devio.c
> through libusb, and in-kernel driver. Currently, only usb-storage
> observes the locking protocol. The most popular device which locks
> in case of simultaneous access is TEAC CD-210PU.

Perfect. Patch queued, thanks Pete.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at