Bug 813810

Summary:	plug small race window at the end of block_stream command
Product:	Red Hat Enterprise Linux 6	Reporter:	Paolo Bonzini <pbonzini>
Component:	qemu-kvm	Assignee:	Paolo Bonzini <pbonzini>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.3	CC:	acathrow, areis, bsarathy, dyasny, flang, juzhang, kwolf, minovotn, mkenneth, mtosatti, pbonzini, shu, virt-maint
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	qemu-kvm-0.12.1.2-2.286.el6	Doc Type:	Bug Fix
Doc Text:	NEEDINFO	Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-06-20 11:46:51 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	806280, 813862

Description Paolo Bonzini 2012-04-18 13:22:47 UTC

Kevin noted how the part of stream_run() that is after the for loop runs with s->common.busy = false. At least bdrv_change_backing_file() can yield, possibly other functions, too.

The race window is really small but it's there.  We can extend the implementation of block_job_cancel_sync so that the race can be fixed easily.

The same patches help fixing the case where the target of a mirroring job fails during block_job_cancel_sync, as suggested by Marcelo.

[To qa: it is very hard to cover these particular cases with tests, but the streaming and mirroring tests---for example switching mirroring to the target, and quit during streaming---will ensure that the code works well].

Comment 4 Michal Novotny 2012-05-04 13:31:11 UTC

    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
NEEDINFO

Comment 7 errata-xmlrpc 2012-06-20 11:46:51 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2012-0746.html