Bug 799386 – The futex proxy handler grabs the pi_lock without disabling interrupts

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Bug 799386 - The futex proxy handler grabs the pi_lock without disabling interrupts

Summary:	The futex proxy handler grabs the pi_lock without disabling interrupts

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise MRG
Classification:	Red Hat
Component:	realtime-kernel (Show other bugs)
Sub Component:
Version:	2.2
Hardware:	Unspecified Unspecified

Priority	unspecified Severity unspecified
Target Milestone:	2.2
Target Release:	---
Assigned To:	John Kacur
QA Contact:	David Sommerseth
Docs Contact:

URL:
Whiteboard:
Keywords:

Depends On:
Blocks:
	Show dependency tree / graph

Reported:	2012-03-02 11:02 EST by Steven Rostedt
Modified:	2016-05-22 19:34 EDT (History)
CC List:	5 users (show)

See Also:
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:	Cause: Interrupts can take the same pi_lock as the task Consequence: Deadlock from an interrupt taking the pi_lock Fix: Disable interrupts when taking pi_lock Result: Deadlock is prevented.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2012-09-19 14:03:29 EDT
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
Disable interrupts when taking pi_lock() (1.19 KB, patch) 2012-03-02 11:04 EST, Steven Rostedt	no flags	Details \| Diff
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2012:1282	normal	SHIPPED_LIVE	Moderate: kernel-rt security, bug fix, and enhancement update	2012-09-19 18:02:30 EDT

Groups: None (edit)

Description Steven Rostedt 2012-03-02 11:02:19 EST

The futex proxy handler grabs the task's pi_lock without disabling interrupts. If an interrupt were to come in while the lock was held, and that interrupt took the same pi_lock, it would cause a deadlock.

Comment 1 Steven Rostedt 2012-03-02 11:04:22 EST

Created attachment 567095 [details]
Disable interrupts when taking pi_lock()

Use raw_spin_lock_irq() instead of raw_spin_lock() when taking pi_lock in the futex proxy handler.

Comment 2 John Kacur 2012-05-23 09:15:57 EDT

The fix here is equivalent to 9358ad7
git describe --contains 9358ad7
v3.2.14-rt24~10

Modifying kernel-rt.spec to document this.

Comment 5 John Kacur 2012-06-20 17:17:18 EDT

    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:
Cause: Interrupts can take the same pi_lock as the task
Consequence: Deadlock from an interrupt taking the pi_lock
Fix: Disable interrupts when taking pi_lock
Result: Deadlock is prevented.

Comment 7 Steven Rostedt 2012-07-03 10:24:34 EDT

The patch was added to 3.2.14-rt24 (upstream stable-rt).

Comment 10 errata-xmlrpc 2012-09-19 14:03:29 EDT

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/RHSA-2012-1282.html

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