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From: Jeff Garzik <jgarzik@pobox.com>
To: Tejun Heo <htejun@gmail.com>
Cc: linux-ide@vger.kernel.org, albertcc@tw.ibm.com
Subject: Re: [PATCH 09/13] libata: fix handling of race between timeout and completion
Date: Thu, 26 Jan 2006 22:55:59 -0500	[thread overview]
Message-ID: <43D999CF.7020707@pobox.com> (raw)
In-Reply-To: <11379893774038-git-send-email-htejun@gmail.com>

Tejun Heo wrote:
> If a qc completes after SCSI timer expires but before libata EH kicks
> in, the qc gets completed but the scsicmd still gets passed to libata
> EH resulting in ->eng_timeout invocation with NULL qc.  Currently none
> of ->eng_timeout callbacks handles this properly.  This patch makes
> ata_scsi_error() bypass ->eng_timeout and handle this rare case.
> 
> Signed-off-by: Tejun Heo <htejun@gmail.com>

Doesn't look right to me.  If the qc gets completed, then the SCSI 
command should have also been completed.

AFAICS the race is this:  if the qc is completed, then there is no 
active tag, so ata_qc_from_tag() correctly returns NULL.  This case is 
really an "error has already been handled" case.  It looks really wrong 
to even touch a scsicmd.  I would just clear the eh_cmd list and be done 
with it.

	Jeff



  reply	other threads:[~2006-01-27  3:56 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-01-23  4:09 [PATCHSET] libata: various fixes related to EH, take #2 Tejun Heo
2006-01-23  4:09 ` [PATCH 04/13] ahci: fix err_mask setting in ahci_host_intr Tejun Heo
2006-01-27  3:36   ` Jeff Garzik
2006-01-23  4:09 ` [PATCH 03/13] libata: fix ata_qc_issue() error handling Tejun Heo
2006-01-23  4:09 ` [PATCH 02/13] libata: make the owner of a qc responsible for freeing it Tejun Heo
2006-01-23  4:09 ` [PATCH 05/13] libata: add detailed AC_ERR_* flags Tejun Heo
2006-01-23  4:09 ` [PATCH 07/13] SCSI: export scsi_eh_finish_cmd() and scsi_eh_flush_done_q() Tejun Heo
2006-01-23  7:09   ` Jeff Garzik
2006-01-23  7:26   ` Arjan van de Ven
2006-01-23  8:20     ` Tejun Heo
2006-01-23  9:36       ` Christoph Hellwig
2006-01-23 10:05         ` Tejun Heo
2006-01-24 17:11           ` Luben Tuikov
2006-01-24 17:20             ` Arjan van de Ven
2006-01-24 18:25               ` Luben Tuikov
2006-01-24 17:30             ` Jeff Garzik
2006-01-24 18:53               ` Luben Tuikov
2006-01-23 14:52   ` Tejun Heo
2006-01-23  4:09 ` [PATCH 06/13] libata: return AC_ERR_* from issue functions Tejun Heo
2006-01-23  4:09 ` [PATCH 01/13] libata: fold __ata_qc_complete() into ata_qc_free() Tejun Heo
2006-01-27  3:34   ` Jeff Garzik
2006-01-23  4:09 ` [PATCH 09/13] libata: fix handling of race between timeout and completion Tejun Heo
2006-01-27  3:55   ` Jeff Garzik [this message]
2006-01-27  3:58     ` Jeff Garzik
2006-02-01 15:36     ` Tejun Heo
2006-02-09  6:21       ` Jeff Garzik
2006-01-23  4:09 ` [PATCH 08/13] libata: implement and apply ata_eh_qc_complete/retry() Tejun Heo
2006-01-23  4:09 ` [PATCH 12/13] libata: create pio/atapi task queueing wrappers Tejun Heo
2006-01-27  4:02   ` Jeff Garzik
2006-01-23  4:09 ` [PATCH 11/13] libata: implement ATA_FLAG_IN_EH port flag Tejun Heo
2006-01-27  4:00   ` Jeff Garzik
2006-01-23  4:09 ` [PATCH 10/13] libata: kill NULL qc handling from ->eng_timeout callbacks Tejun Heo
2006-01-23  4:09 ` [PATCH 13/13] libata: EH / pio tasks synchronization Tejun Heo

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