From: Jeff Garzik <jgarzik@pobox.com>
To: Tejun Heo <htejun@gmail.com>,
linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Jens Axboe <axboe@suse.de>, Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: libata error handling
Date: Thu, 18 Aug 2005 23:49:19 -0400 [thread overview]
Message-ID: <430556BF.5070004@pobox.com> (raw)
In-Reply-To: <20050807054850.GA13335@htj.dyndns.org>
Tejun,
In an email I cannot find anymore, you asked why I was interested in
converting libata to use the fine-grained EH hooks in the SCSI layer,
rather than continued with the current ->eh_strategy_handler() method.
Several reasons:
1) The fine-grained hooks of the SCSI layer are somewhat standard for
block devices. The events they signify -- timeout, abort cmd, dev
reset, bus reset, and host reset -- map precisely to the events that we
must deal with at the ATA level.
But be warned of false sharing, as I talk about in #2...
2) When libata SAT translation layer becomes optional, and libata drives
a "true" block device, use of ->eh_strategy_handler() will actually be
an obstacle due to false sharing of code paths. ->eh_strategy_handler()
is indeed a single "do it all" EH entrypoint, but within that entrypoint
you must perform several SCSI-specific tasks.
3) ->eh_strategy_handler() has continually proven to be a method of
error handling poorly supported by the SCSI layer. There are many
assumption coded into the SCSI layer that this is -not- the path taken
by LLD EH code, and libata must constantly work around these assumptions.
4) libata is the -only- user of ->eh_strategy_handler(), and oddballs
must be stomped out. It creates a maintenance burden on the SCSI layer
that should be eliminated.
next prev parent reply other threads:[~2005-08-19 3:49 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-29 5:06 [RFC][PATCH] libata ATAPI alignment Jeff Garzik
2005-07-29 13:38 ` Alan Cox
2005-08-02 8:27 ` Jens Axboe
2005-08-02 14:31 ` Jeff Garzik
2005-08-07 5:48 ` Tejun Heo
2005-08-07 5:53 ` [PATCH 1/2] sata: fix sata_sx4 dma_prep to not use sg->length Tejun Heo
2005-08-10 21:24 ` Jeff Garzik
2005-08-07 5:58 ` Rd: [PATCH 2/2] sata: implement ATAPI alignment adjustment Tejun Heo
2005-08-07 6:17 ` [PATCH 3] sata: restore sg on setup failure Tejun Heo
2005-08-19 3:49 ` Jeff Garzik [this message]
2005-08-19 5:40 ` libata error handling Tejun Heo
2005-08-19 5:54 ` Jeff Garzik
2005-08-19 19:00 ` Luben Tuikov
2005-08-19 18:46 ` Luben Tuikov
2005-08-19 19:38 ` Patrick Mansfield
2005-08-19 20:03 ` Luben Tuikov
2005-08-19 20:11 ` Patrick Mansfield
2005-08-19 20:43 ` Luben Tuikov
2005-08-19 21:10 ` Patrick Mansfield
2005-08-19 22:37 ` Luben Tuikov
2005-08-19 20:29 ` Mike Anderson
2005-08-19 21:02 ` Luben Tuikov
2007-01-06 14:26 Kasper Sandberg
[not found] <fa.pdj7pJD9C08bRZatFINV1hz1oyA@ifi.uio.no>
2007-01-06 18:21 ` Robert Hancock
2007-01-06 18:57 ` Kasper Sandberg
2007-01-06 19:01 ` Robert Hancock
2007-01-06 19:08 ` Kasper Sandberg
2007-01-06 19:28 ` Bartlomiej Zolnierkiewicz
2007-01-07 20:07 ` Kasper Sandberg
2007-01-07 20:38 ` Bartlomiej Zolnierkiewicz
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