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Date: Fri, 7 Jan 2011 16:33:02 -0500
From: Tejun Heo <tj@kernel.org>
To: Jeff Garzik <jeff@garzik.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Nick Piggin <npiggin@kernel.dk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Chris Mason <chris.mason@oracle.com>,
        Frank Rowand <frank.rowand@am.sony.com>, Ingo Molnar <mingo@elte.hu>,
        Thomas Gleixner <tglx@linutronix.de>, Mike Galbraith <efault@gmx.de>,
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        linux-kernel@vger.kernel.org, Jeremy Fitzhardinge <jeremy@goop.org>,
        Linux-Arch <linux-arch@vger.kernel.org>,
        linux-scsi <linux-scsi@vger.kernel.org>,
        IDE/ATA development list <linux-ide@vger.kernel.org>
Subject: Re: [RFC][PATCH] spinlock: Kill spin_unlock_wait()
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Hello, Jeff.

On Fri, Jan 07, 2011 at 04:13:53PM -0500, Jeff Garzik wrote:
> > 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.

Hmm... but they don't use ata_scsi_error() and ->eng_timeout() at all,
no?  We can't remove phy_reset() and need to keep the silly "if
(->error_handler)" tests around but should be able to remove those
from ata_scsi_error() and other EH routines, at least.  Am I missing
something?

Thanks.

-- 
tejun