[Bug tdep/30252] gdb-13.1/gdb/target.c:2641: internal-error: target_resume: Assertion `inferior_ptid != null_ptid' failed

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=30252

--- Comment #9 from cvs-commit at gcc dot gnu.org <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=b2ad7bb9e6a012699195d3eda9d40679c406ebdc

commit b2ad7bb9e6a012699195d3eda9d40679c406ebdc
Author: Pedro Alves <pedro@palves.net>
Date:   Thu Jul 6 15:05:11 2023 +0100

    Fix Solaris regression (PR tdep/30252)

    PR tdep/30252 reports that using GDB on Solaris fails an assertion in
    target_resume:

     target.c:2648: internal-error: target_resume: Assertion `inferior_ptid !=
null_ptid' failed.
     A problem internal to GDB has been detected,
     further debugging may prove unreliable.
     Quit this debugging session? (y or n)

    The backtrace, after running it through c++filt, looks like:

     ----- Backtrace -----
     0xa18914 gdb_internal_backtrace_1
             /root/binutils-gdb/gdb/bt-utils.c:122
     0xa18914 gdb_internal_backtrace()
             /root/binutils-gdb/gdb/bt-utils.c:168
     0xdec834 internal_vproblem
             /root/binutils-gdb/gdb/utils.c:401
     0xdecad8 internal_verror(char const*, int, char const*, __va_list_tag*)
             /root/binutils-gdb/gdb/utils.c:481
     0xf3638c internal_error_loc(char const*, int, char const*, ...)
             /root/binutils-gdb/gdbsupport/errors.cc:58
     0xd70580 target_resume(ptid_t, int, gdb_signal)
             /root/binutils-gdb/gdb/target.c:2648
     0xc59e85 procfs_target::wait(ptid_t, target_waitstatus*,
enum_flags<target_wait_flag>)
             /root/binutils-gdb/gdb/procfs.c:2187
     0xcf6da7 sol_thread_target::wait(ptid_t, target_waitstatus*,
enum_flags<target_wait_flag>)
             /root/binutils-gdb/gdb/sol-thread.c:442
     0xd73711 target_wait(ptid_t, target_waitstatus*,
enum_flags<target_wait_flag>)
             /root/binutils-gdb/gdb/target.c:2586
     ...

    The problem is that the procfs backend, while inside target_wait,
    called target_resume without switching to the leader thread of that
    resumption.

    The target_resume interface is:

     /* Resume execution (or prepare for execution) of the current thread
        (INFERIOR_PTID), while optionally letting other threads of the
        current process or all processes run free.
        ...

    Thus calling target_resume with inferior_ptid == null_ptid is bogus.

    target_wait (which leads to procfs_target::wait on Solaris) is called
    with inferior_ptid == null_ptid on entry exactly to help catch such
    bogus uses.

    From the backtrace, it seems that the relevant line in question is
    procfs.c:2187:

    2186  /* How to keep going without returning to wfi: */
    2187  target_continue_no_signal (ptid);
    2188  goto wait_again;

    target_continue_no_signal is a small wrapper around target_resume,
    which would make sense.

    The fix is to not call target_resume or go via the target stack at
    all.  Instead, factor out a new proc_resume function out of
    procfs_target::resume, and call that.  The new function does not rely
    on inferior_ptid.

    I've not been able to test it myself, but Petr confirmed it fixes the
    assertion failure with his test case, and Marcel Telka also confirmed
    it solves the problem.

    Tested-By: Petr Å umbera <petr.sumbera@oracle.com>
    Tested-By: Marcel Telka <marcel@telka.sk>
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30252
    Change-Id: I6213c59b081d400a22e799ee621c2eff6dcafbf3

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