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Date: Fri, 7 Jan 2011 16:13:53 -0500
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Subject: Re: [RFC][PATCH] spinlock: Kill spin_unlock_wait()
From: Jeff Garzik <jeff@garzik.org>
To: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Nick Piggin <npiggin@kernel.dk>,
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On Fri, Jan 7, 2011 at 4:01 PM, Tejun Heo <tj@kernel.org> wrote:
> On Thu, Jan 06, 2011 at 07:26:35PM +0100, Peter Zijlstra wrote:
>> Jeff, Tejun, could you look at the ata-eh thing, then I'll put sorting
>> through the futex thing on my todo list.
>
> Hmm... I think the ->eng_timeout path is already dead.  We no longer
> have any in-kernel implementation, so killing spin_unlock_wait()
> should be fine.  I'll follow up with removal of the unused callback.

Unfortunately...  libsas continues to avoid the new EH :(

It's a hairy mess to untangle, too.  libata does proper error handling
of ATA device errors, notably NCQ error handling, which libsas sorely
misses.  But libata new EH assumes a bit too much about "owning" the
entirety of the EH process.  These assumptions are proper for wholly
ATA drivers (drivers/ata/*) where new EH can drive the EH process, but
in the SAS situation, a phy in SATA mode is simply a subset of a
larger set of EH conditions that must be handled.

Thus libsas uses the ancient libata hook ->phy_reset and lacks ->error_handler.

I think libata's old-EH path is entirely SAS-specific at this point.

     Jeff


P.S.  Note that libsas and ipr are peers; thus ipr driver also uses old EH.