On Fri, 11 Feb 2005 11:16:20 +0100 Duncan Sands <[EMAIL PROTECTED]> wrote:
> On Thu, 2005-02-10 at 16:11 -0800, Pete Zaitcev wrote: > > 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. > > How does this compare with the locking in 2.6 kernels? In 2.6, there is no locking whatsoever. Instead, rules for queueing are relaxed for all HCs. If the device chokes when it receives a control together with a data exchange (on a bulk endpoint, usually), kernel does not interfere. Users (libusb & drivers) are supposed to know when not to do it. Obviously, it's not the case of usb-storage. To help that, descriptor strings are cached in latest Greg's trees, since a week ago or so. This way at least "cat /proc/bus/usb/devices" won't interfere. -- Pete - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
