[Bug gdb/31555] New: Cannot attach to program after its main thread has exited, on Linux

[Bug gdb/31555] New: Cannot attach to program after its main thread has exited, on Linux

[pedro at palves dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=31555

            Bug ID: 31555
           Summary: Cannot attach to program after its main thread has
                    exited, on Linux
           Product: gdb
           Version: unknown
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: pedro at palves dot net
  Target Milestone: ---

On Linux, it is not possible to attach to a process after its main thread has
exited.  Ptrace does not let you attach to zombie threads.  E.g., with the
gdb.threads/leader-exit.exp test program:

$ gdb -p 1804363
...
Attaching to process 1804363
warning: process 1804363 is a zombie - the process has already terminated
ptrace: Operation not permitted.
(gdb)


This is possible on other systems -- at least on Windows it is.

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[Bug gdb/31555] Cannot attach to program after its main thread has exited, on Linux

[pedro at palves dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=31555

Pedro Alves <pedro at palves dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |*-*-linux*

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[Bug gdb/31555] Cannot attach to program after its main thread has exited, on Linux

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31555

--- Comment #1 from Sourceware Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Pedro Alves <palves@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ec48903170926f3827144525b50ddd3c6ae3fbf0

commit ec48903170926f3827144525b50ddd3c6ae3fbf0
Author: Pedro Alves <pedro@palves.net>
Date:   Mon Mar 25 15:17:02 2024 +0000

    New testcase gdb.threads/leader-exit-attach.exp (PR threads/8153)

    Add a new testcase for exercising attaching to a process after its
    main thread has exited.

    This is not possible on Linux, the kernel does not allow attaching to
    a zombie task, so the test is kfailed there.  It is possible however
    on Windows at least, and was the scenario addressed by the Windows
    backend fix in
    https://sourceware.org/legacy-ml/gdb-patches/2003-12/msg00479.html,
    nowadays PR threads/8153, back in 2003.

    Passes cleanly on Cygwin.
    KFAILed on GNU/Linux native and gdbserver.

    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=8153
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31554
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31555
    Change-Id: Ib554f92f68c965bb4603cdf2aadb55ca45ded53b

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