Re: A really interesting mass-storage BUG introduced after 2.6.18

[Alan Stern]

On Sun, 11 Jan 2009, [UTF-8] Ozan Ã?aÄ?layan wrote:

> Hi,
> 
> One of our users reported[0] that his 128MB mass storage driver doesn't 
> work anymore on our current stock kernel 2.6.25.20 by hotplugging but 
> works flawlessly if it was plugged before booting the OS. He also said 
> that it was working out of the box with our old kernel 2.6.18. I 
> gathered a lot of output and debugging stuff from the user[1][2] and 
> found out that the device has some problems with SCSI Inquiry commands 
> then I discovered the patch of Alan Stern about the bad residue 
> values[3], backported it and no way it didn't solve the problem.
> 
> I also suggested to give a try to the current stable 2.6.28 but the 
> behaviour is still the same.
> 
> When hotplugged, the kernel doesn't detect the partitions in the device 
> leaving the block device on its own but if it's plugged during the boot, 
> the partitions are correctly detected and have their own /sys/block 
> entries. Note that the device reports a "usb embedded hub" beside a mass 
> storage device (dunno if it's the case with all of these kind devices).
> 
> [0]: http://bugs.pardus.org.tr/show_bug.cgi?id=8369
> [1]: http://bugzilla.kernel.org/show_bug.cgi?id=11125
> [2]: http://bugs.pardus.org.tr/attachment.cgi?id=3553 (Hotplugged dmesg 
> output)
> [3]: http://bugs.pardus.org.tr/attachment.cgi?id=3561 (Coldplug dmesg 
> output, correctly detected)

Please ask Antoon to collect a usbmon log during a hotplug test.  The 
instructions are in Documentation/usb/usbmon.txt.

Alan Stern

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