Re: IDE Floppy support for IOMEGA Zip Drive broken in 3.16 -> 3.17 transition

From: Sergio Callegari
Date: Thu Aug 20 2015 - 11:09:09 EST


Hi Christoph,

thanks for your answer!

Any clue on how to help/speed up this? Was there any exchange with them when you first provided your patch back in 2014? Can it be restarted?

My feeling is that the issue fixed with 045065d8a300a37218c548e9aa7becd581c6a0e8 was in fact the real paper over the bug. As distros start picking kernels with 045065d8a300a37218c548e9aa7becd581c6a0e8 the issue is like to bite more and more.

And it is a subtle bug. In some cases takes ages before revealing, making one feel confident on a system that is in fact broken. And takes ages to bisect (took me almost 7 days).

Best,

Sergio



On 20/08/2015 10:08, Christoph Hellwig wrote:
Hi Sergio,

On Tue, Aug 18, 2015 at 09:44:28AM +0200, Sergio Callegari wrote:
Hi,

I have bisected the issue down to

[045065d8a300a37218c548e9aa7becd581c6a0e8] [SCSI] fix qemu boot hang problem

Bisecting has been a painful job due to the fact that the bug may show only
many hours after the system boot.

The commit above in fact is not the culprit, but a fix to an issue that was
hiding the real bug on my system. See

http://marc.info/?l=linux-kernel&m=143973820612978&w=2

The real issue is with sata host lock and seems to be biting a few other
people as well

https://bbs.archlinux.org/viewtopic.php?id=189324

A patch fixing the issue was sent to the LKML back in Nov 2014 by Christoph
Hellwig (who is reading in CC)

https://lkml.org/lkml/2014/11/20/581

I have tested the patch and it works for me.

What is expected to happen now?
As mentioned in that thread we need more input from the libata people
on what kind of race this is papering over.

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