On Tue, 12 Apr 2005, Shiju Mathew wrote:
> Hi,
> I have a usb cdrom device. When the cdrom device is opened for more
> than two times simultaneouly and try to access it through ioctl,
> except two all the others gets blocked at ioctl call. In my case I
> open the cdrom device and call the ioctl CDROM_DRIVE_STATUS .When
> calling from the third instant the first or the second instant will
> get blocked at ioctl call. I could not find this problem on non-usb
> cdroms. Is this a know issue. Is there a patch to resolve it. Could
> someone help me to resolve it..
> I am doing the tesing on 2.6.11 and 2.6.12-rc2 kernel.
>
>
> fd = open("/dev/cdrom", O_RDONLY | O_NONBLOCK)
> while (1)
> ioctl (fd, CDROM_DRIVE_STATUS, &header)
I haven't heard of this problem before. Can you please turn on USB Mass
Storage verbose debugging in your kernel configuration, and send the
debugging log showing what happens when you run your test? Also, while
one of the processes is blocked, can you get a stack trace with
Alt-SysRq-T and post it too?
Alan Stern
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