Bug 1299810

Description of problem:
The algorithm used to determine if a device is blacklisted in scsi_dev_info_list is buggy in kernels < 4.4 . As a consequence, some legitimate devices get blacklisted because of false positives.

This bug has been fixed by two patches by Alan Stern, already merged in 4.4. I am opening this report to ask for the backporting of the patches to kernel 4.3 for fedora 23: I have been applying the patch myself and compiling kernel rpms since august in the hope the fix will be eventually merged, but it ended up in 4.4 and I don't know if fedora 23 will switch to that kernel.

The git commit ids for the two patches are:
c42b3654f48bc06189a2d99629c9cf7bb79e8fe3
b704f70ce2003c8046d5c0128303aeeb0d93d890

See here for details:

https://git.kernel.org/cgit/linux/kernel/git/jejb/scsi.git/patch/?id=c42b3654f48bc06189a2d99629c9cf7bb79e8fe3
https://git.kernel.org/cgit/linux/kernel/git/jejb/scsi.git/patch/?id=b704f70ce2003c8046d5c0128303aeeb0d93d890


Version-Release number of selected component (if applicable):

Kernel 4.3.x and lower

How reproducible:

Always

Steps to Reproduce:
1. Connect a Inateck FD2003 docking station with two hard disks inserted.

Actual results:
Only the first hard disk is detected.

Expected results:
Both hard disks should be detected.


Additional info:

This device product string is made up by whitespaces. The current blacklist code matches it with entry
{"", "Scanner", "1.80", BLIST_NOLUN} 
and as a consequence it enables only the first logical unit of the device.

A more detailed explanation is provided in Alan Stern's comments in both the patches.

You can also read the original discussion between me and Alan Stern here:
http://comments.gmane.org/gmane.linux.usb.general/128504