Bug 682265

Summary:	[RHEL 6] libsas: flush initial device discovery before completing ->scan_finished()
Product:	Red Hat Enterprise Linux 6	Reporter:	David Milburn <dmilburn>
Component:	kernel	Assignee:	David Milburn <dmilburn>
Status:	CLOSED ERRATA	QA Contact:	Gris Ge <fge>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	6.1	CC:	bdonahue, dan.j.williams, ed.ciechanowski, fge, jgarzik, peterm, rdoty
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel-2.6.32-130.el6	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-05-19 12:00:32 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description David Milburn 2011-03-04 16:17:15 UTC

It is possible that all initial discovery events have not completed
during scsi scan, DISCE_DISCOVER_DOMAIN events are queued up in sas_form_port
while processing the PORTE_BYTES_DMAED events.

Posted upstream:

http://marc.info/?l=linux-scsi&m=129791077719331&w=2

During initial scan libsas drivers start their phys and notify libsas
with PORTE_BYTES_DMAED events as port links are established.  This
notification in turn causes libsas to post DISCE_DISCOVER_DOMAIN events
to the queue.  Calling scsi_flush_work() at the end of scan_finished
guarantees that all preceding PORTE_BYTES_DMAED events have been
registered in the queue, but it does not guarantee that the resulting
DISCE_DISCOVER_DOMAIN events have been processed because
flush_workqueue() explicitly avoids live-locking with incoming work.

Introduce sas_flush_discovery() to guarantee that all initial discovery
events have completed.  It is called after the driver determines all
initial PORTE_BYTES_DMAED events have had a chance to enter the queue.
This does not cover BCNs that are generated during expander bring up,
only the initial sas_discover_domain() event.

Comment 3 RHEL Program Management 2011-03-04 17:19:45 UTC

This request was evaluated by Red Hat Product Management for inclusion
in a Red Hat Enterprise Linux maintenance release. Product Management has 
requested further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed 
products. This request is not yet committed for inclusion in an Update release.

Comment 4 Aristeu Rozanski 2011-04-07 13:50:02 UTC

Patch(es) available on kernel-2.6.32-130.el6

Comment 8 errata-xmlrpc 2011-05-19 12:00:32 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0542.html