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-kvmAssignee: Paolo Bonzini <pbonzini>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 6.3CC: 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