On Thu, Jul 10, 2008 at 02:36, Leonid <leonidv11@xxxxxxxxx> wrote:
> I believe a bug has been introduced in recent Linux kernels that
> causes udev rules to not be applied when the system is overloaded with
> other tasks. This is more easily seen on single core machines since
> it is easier to overload the system.
>
> My goal is to give all users read and write permissions to a USB
> device. To more easily reproduce the problem, I used a pre-existing
> hardware test circuit where I can automatically plug and unplug a USB
> device through software control. At the same time I had the OS
> writing a large file over NFS with the "dd" command and performing
> other tasks if needed. Intermittently, my permissions were not being
> properly set by udev. Everything else about the enumeration process
> with the device was correct.
>
> I am using an un-programmed Cypress microcontroller as my device.
> These devices have a VID of 0x04B4 and a PID of 0x8613. Therefore, my
> udev rules file /etc/udev/rules.d/99-test.rules is simply:
>
> ACTION=="add", SUBSYSTEMS=="usb", ATTRS{idVendor}=="04b4",
> ATTRS{idProduct}=="8613", MODE="0666"
>
> The problem appears under kernel 2.6.25.6 and 2.6.25.9 on different
> motherboards. It can also be reproduced (albeit intermittently) when
> manually attaching USB devices to the system, as opposed to using my
> convenient automated hardware circuit. The same behavior was also
> observed with a full-speed device.
>
> I have tried this on kernel 2.6.23.1 and found that this was not
> susceptible to this issue. I have also tried 118 and 124 versions of
> udev, and found that these particular versions of udev had no effect
> on the pass/failure rate of the test.
>
> Any help would be much appreciated.
I guess you need:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=2e5f10e4f0a9649186d8a8c793822b2e0dae8373
Kay
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