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Bug 672234 - add POLLPRI to sock_def_readable()
Summary: add POLLPRI to sock_def_readable()
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel
Version: 6.0
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Jiri Pirko
QA Contact: Network QE
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2011-01-24 14:50 UTC by Veaceslav Falico
Modified: 2018-11-14 15:35 UTC (History)
8 users (show)

Fixed In Version: kernel-2.6.32-128.el6
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2011-05-23 20:38:37 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
reproducer source code (2.15 KB, text/plain)
2011-01-24 14:50 UTC, Veaceslav Falico 		no flags Details
upstream patch fixed to apply cleanly (508 bytes, patch)
2011-01-24 14:51 UTC, Veaceslav Falico 		no flags Details | Diff
View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2011:0542 0 normal SHIPPED_LIVE Important: Red Hat Enterprise Linux 6.1 kernel security, bug fix and enhancement update 2011-05-19 11:58:07 UTC

Description Veaceslav Falico 2011-01-24 14:50:27 UTC 
Created attachment 474968 [details]
reproducer source code

The poll() could block forever on tcp sockets and Urgent data was received,
if the event flag only contains POLLPRI. This bug is introduced by commit
4938d7e0233 (poll: avoid extra wakeups in select/poll). Problem is that
TCP sockets use standard sock_def_readable() function for their
sk_data_ready() handler, and sock_def_readable() doesnt signal POLLPRI.

Only TCP is affected by the problem. Adding POLLPRI to the list of flags
might trigger unnecessary schedules, but URGENT handling is such a seldom used
feature this seems a good compromise.

Upstream commit: http://marc.info/?l=git-commits-head&m=129436629005347&w=2

Red Hat Enterprise Linux Version Number: RHEL6
Release Number: 6.0
Architecture: x86_64
Kernel Version: kernel-2.6.32-71.el6 


Step to Reproduce:

1. #gcc -o pollpri pollpri.c
2. #./pollpri


Actual Results:

After the message of "parent: waiting for child to exit" was printed by pollpri,
pollpri hanged up forever.

Expected Results:

The pollpri program can exit normally.

Attaching pollpri.c and line-fixed patch for rhel6 git.
Comment 1 Veaceslav Falico 2011-01-24 14:51:45 UTC 
Created attachment 474969 [details]
upstream patch fixed to apply cleanly
Comment 2 Neil Horman 2011-01-27 18:42:56 UTC 
Triage assignment.  If you feel this bug doesn't belong to you, or that it cannot be handled in a timely fashion, please contact me for re-assignment
Comment 4 RHEL Program Management 2011-02-01 05:28:34 UTC 
This request was evaluated by Red Hat Product Management for
inclusion in the current release of Red Hat Enterprise Linux.
Because the affected component is not scheduled to be updated
in the current release, Red Hat is unfortunately unable to
address this request at this time. Red Hat invites you to
ask your support representative to propose this request, if
appropriate and relevant, in the next release of Red Hat
Enterprise Linux. If you would like it considered as an
exception in the current release, please ask your support
representative.
Comment 5 RHEL Program Management 2011-03-01 23:20:03 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 8 Aristeu Rozanski 2011-03-30 14:31:37 UTC 
Patch(es) available on kernel-2.6.32-128.el6
Comment 13 errata-xmlrpc 2011-05-23 20:38:37 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
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