linux-kernel - Re: [SCSI] fix media change events for polled devices

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Date:	Fri, 21 Mar 2008 16:36:32 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	James Bottomley <James.Bottomley@...senPartnership.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kay Sievers <kay.sievers@...y.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-scsi@...r.kernel.org
Subject: Re: [SCSI] fix media change events for polled devices

James Bottomley wrote:
> On Fri, 2008-03-21 at 13:12 -0400, Jeff Garzik wrote:
>> Linux Kernel Mailing List wrote:
>>>     [SCSI] fix media change events for polled devices
>>>     
>>>     Commit:
>>>       a341cd0f (SCSI: add asynchronous event notification API)
>>>     breaks:
>>>       285e9670 (sr,sd: send media state change modification events)
>>>     by introducing an event filter, which is removed here, to make
>>>     events, we are depending on, happen again.
>>
>> By simply reading the code history, it is trivial to verify that this 
>> description is false:
>>
>> Commit 285e9670 depends on a341cd0f, so by definition it is 285e9670 -- 
>> or rather the incomplete update of your original patch that resulted in 
>> 285e9670 -- that is broken.
>>
>> Since commit 285e9670 is broken, you fixed the wrong thing.
>>
>> Furthermore, you broke a userspace interface that was introduced by 
>> a341cd0f, by removing the event filter controlled by userspace.
> 
>> Did anyone bother to read any code at all?
> 
> Yes, I did.  The userspace interface has never worked as a writeable
> attribute because it's read only (as Kay has pointed out several times).
> Based on that, I just #if'd out the filter code to get polled media
> events working again.

It has a show attribute and was obviously intended as a writable 
interface (and I should know, I wrote it).


> The filter can be put back with a better discriminator for 2.6.26
> 
>> When 285e9670 was updated for the scsi_evt_* interface, it should have 
>> initialized the supported_events mask.
> 
> That would break HAL ... it's using the presence of the media_event flag
> in the variable to indicate it doesn't need to poll.  We need two flags,
> one for polling and one for AN.

Oh for pete's sake.  How hard is it to create a second bit _and_ keep 
the existing AN featureset working?

_YOU_ are the one that broke this stuff in the first place, can you 
please take two seconds to fix it without breaking other stuff?

	Jeff



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