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Bug 232369

Summary:	Exit notifications missing when tracing multi-threaded processes
Product:	Red Hat Enterprise Linux 5	Reporter:	Roland McGrath <roland>
Component:	kernel	Assignee:	Roland McGrath <roland>
Status:	CLOSED ERRATA	QA Contact:	Martin Jenner <mjenner>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	5.0	CC:	kernel-mgr, roland
Target Milestone:	---	Keywords:	Regression
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	RHBA-2007-0959	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2007-11-07 19:44:17 UTC	Type:	---
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:	232236
Bug Blocks:

Description Roland McGrath 2007-03-15 01:03:45 UTC

+++ This bug was initially created as a clone of Bug #232236 +++

Description of problem:
When tracing multiple threads in a process using ptrace the Fedora Core kernel
only delivers an exit notification through wait for the initial thread. Vanilla
Linux kernels deliver an exit notification for each traced thread.

Version-Release number of selected component (if applicable):
2.6.19-1.2911.6.5.fc6

How reproducible:
Every time.

Steps to Reproduce:
1. Untar the attached test.
2. cd exit-test
3. make
4. ./monitor

Actual results:
Prints only one exit notification.

Expected results:
Should print two exit notifications.

Additional info:

For a less synthetic testcase, strace is also affected by this. Try compiling
this program with "gcc -fopenmp -o foo foo.c":

int main(int argc, char **argv) {
    int i;
#pragma omp parallel for
    for (i = 0; i < 1; i++)
        ;

    return 0;
}

Then trace it with "strace -f ./foo". Strace reports multiple detaches for the
same thread or bogus SIGSEGVs:

...
[pid  4586] futex(0x886b048, FUTEX_WAKE, 1) = 1
[pid  4585] <... futex resumed> )       = 0
[pid  4585] futex(0x886b048, FUTEX_WAKE, 1) = 0
[pid  4585] exit_group(0)               = ?
Process 4585 detached
Process 4586 detached
Process 4585 detached

...
[pid  4589] futex(0x19d830, FUTEX_WAIT, 0, NULL <unfinished ...>
[pid  4588] <... futex resumed> )       = 0
[pid  4588] exit_group(0)               = ?
[pid  4589] <... futex resumed> )       = 9
[pid  4589] --- SIGSEGV (Segmentation fault) @ 0 (0) ---

-- Additional comment from magnus_vesterlund on 2007-03-14 11:08 EST --
Created an attachment (id=150042)
Test case


-- Additional comment from cebbert on 2007-03-14 11:13 EST --
Please test 2.6.20-1.2925.fc6

It's in Fedora testing now and should be released today.

-- Additional comment from roland on 2007-03-14 14:53 EST --
Looks like this is still a problem.

-- Additional comment from roland on 2007-03-14 20:14 EST --
Created an attachment (id=150103)
test case contained in one source file

This is the version of the test case I'm using.

-- Additional comment from roland on 2007-03-14 20:56 EST --
Created an attachment (id=150106)
fix patch

I've fixed the bug and the attached patch is now part of the "upstream" utrace
patches.

-- Additional comment from roland on 2007-03-14 21:01 EST --
I've committed the new utrace patch to the rawhide kernel cvs.
The attached patch can be folded into the utrace patch for fc6.

Comment 1 Roland McGrath 2007-03-15 01:07:25 UTC

See attachments to bug #232236 for test case and fix patch.
This is a regression vs RHEL4 and all prior and upstream kernels.
The fix will be included with other utrace updates in a replacement utrace patch
for 5.1.

Comment 2 RHEL Program Management 2007-03-15 02:04:16 UTC

This bugzilla has Keywords: Regression.  

Since no regressions are allowed between releases, 
it is also being proposed as a blocker for this release.  

Please resolve ASAP.

Comment 5 RHEL Program Management 2007-06-20 12:31:41 UTC

This request was evaluated by Red Hat Kernel Team for inclusion in a Red
Hat Enterprise Linux maintenance release, and has moved to bugzilla 
status POST.

Comment 6 Don Zickus 2007-07-19 20:05:34 UTC

in kernel-2.6.18-30.el5

Comment 8 Mike Gahagan 2007-09-11 18:52:29 UTC

confirmed fix using testcase attached as attachment (id=150103)

Comment 10 errata-xmlrpc 2007-11-07 19:44:17 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 the 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/RHBA-2007-0959.html