Bug 4217 - utrace: PTRACE_ATTACH of SIGSTOPped process hangs
Summary: utrace: PTRACE_ATTACH of SIGSTOPped process hangs
Status: RESOLVED FIXED
Alias: None
Product: frysk
Classification: Unclassified
Component: general (show other bugs)
Version: unspecified
: P2 normal
Target Milestone: ---
Assignee: Unassigned
URL:
Keywords:
Depends on:
Blocks: 1496
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Reported: 2007-03-20 13:57 UTC by Andrew Cagney
Modified: 2007-10-04 20:24 UTC (History)
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Description Andrew Cagney 2007-03-20 13:57:11 UTC 
Opened by Jan Kratochvil (jan.kratochvil@redhat.com)  	 on 2007-03-18 13:33
EST  	[reply]  	   Private

Description of problem:
utrace implementation of ptrace(2) is incompatible:
PTRACE_ATTACH on a process being stopped (by SIGSTOP) never returns.
On non-utrace kernels it returns, tested:
  kernel-2.6.20-1.2300.fc5.x86_64
  linux-2.6.17.7.x86_64 (from kernel.org)
  linux-2.6.16-xen.i686 (from kernel.org)

Version-Release number of selected component (if applicable):
kernel-xen-2.6.19-1.2898.2.3.fc7.i686
kernel-2.6.20-1.2925.fc6.i586

How reproducible:
Always.

Steps to Reproduce:
1. Process A should be: kill -STOP process_A_PID
2. Process B should: ptrace (PTRACE_ATTACH, process_A_PID, NULL, NULL);
3. Process B should: waitpid (process_A_PID, &status, 0);

Red Hat bug:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=232837
Comment 1 Jan Kratochvil 2007-10-04 20:24:01 UTC 
Verified as no longer reproducible on:
Fedora-8 (kernel-2.6.23-0.204.rc8.fc8.x86_64)
Fedora-7 (kernel-2.6.22.9-91.fc7.x86_64)
Fedora-6 (kernel-2.6.22.7-57.fc6.x86_64)