Bug 596626 - Create reliable implementation of cancel_(delayed)_work_sync() in RHEL5
Summary: Create reliable implementation of cancel_(delayed)_work_sync() in RHEL5
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.5
Hardware: All
OS: Linux
low
medium
Target Milestone: rc
: ---
Assignee: Oleg Nesterov
QA Contact: Zhouping Liu
URL:
Whiteboard:
Depends On:
Blocks: 582191
TreeView+ depends on / blocked
 
Reported: 2010-05-27 07:19 UTC by Stanislaw Gruszka
Modified: 2014-01-13 00:00 UTC (History)
4 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2011-01-13 21:34:50 UTC


Attachments (Terms of Use)
test_workq kernel module (2.24 KB, text/plain)
2010-12-15 07:33 UTC, Stanislaw Gruszka
no flags Details


Links
System ID Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2011:0017 normal SHIPPED_LIVE Important: Red Hat Enterprise Linux 5.6 kernel security and bug fix update 2011-01-13 10:37:42 UTC

Description Stanislaw Gruszka 2010-05-27 07:19:37 UTC
Description of problem:

(quote from Oleg)
"cancel_rearming_delayed_work + flush_workqueue has the following problems:

	- it hangs forever if the work doesn't rearm itsels (or if
	  it was never queued)

	- in fact it can't cancel the auto-rearming work too, if this
	  work is queued on >1 CPUs. But probably we can ignore this
	  very exotic case.

	- it can hang if called under any LOCK which could be used
	  by any other work which may be queued on the same wq.
"

We have some driver backported from upstream (like wireless stack) which have workqueue handlers like that 

work_func()
{
   if (some_condition)
        return;
   queue_delayed_work(my->workqueue, my->work, delay);
}

We can stop that such work reliable in current RHEL5. We need cancel_delayed_work_sync and cancel_delayed_work with upstream semantics.

Comment 1 RHEL Product and Program Management 2010-05-27 07:41:19 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 2 Oleg Nesterov 2010-05-30 16:25:10 UTC
[RHEL5 PATCH 0/7] bz#596626: implement cancel_work_sync() and cancel_delayed_work_sync()
http://post-office.corp.redhat.com/archives/rhkernel-list/2010-May/msg03169.html

Comment 12 Jarod Wilson 2010-06-14 18:23:47 UTC
in kernel-2.6.18-203.el5
You can download this test kernel from http://people.redhat.com/jwilson/el5

Detailed testing feedback is always welcomed.

Comment 16 Stanislaw Gruszka 2010-12-15 07:33:26 UTC
Created attachment 468781 [details]
test_workq kernel module

I used this module to test workqueues, old kernel hangs within minutes, with patch kernel survive a night and I terminate the test.

Comment 22 errata-xmlrpc 2011-01-13 21:34:50 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-2011-0017.html


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