[Bug gdb/18749] problems if whole process dies while (ptrace-) stopped

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

https://sourceware.org/bugzilla/show_bug.cgi?id=18749

--- Comment #2 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=465a859e0a991d3bfe8a9ee65a29a223c42e2ce7

commit 465a859e0a991d3bfe8a9ee65a29a223c42e2ce7
Author: Pedro Alves <palves@redhat.com>
Date:   Fri Aug 21 19:52:36 2015 +0100

    Fix gdbserver crash exposed by
gdb.threads/process-dies-while-handling-bp.exp

    Running that test in a loop, I found a gdbserver core dump with the
    following back trace:

     Core was generated by `../gdbserver/gdbserver --once --multi :2346'.
     Program terminated with signal SIGSEGV, Segmentation fault.
     #0  0x0000000000406ab6 in inferior_regcache_data (inferior=0x0) at
src/gdb/gdbserver/inferiors.c:236
     236       return inferior->regcache_data;
     (gdb) up
     #1  0x0000000000406d7f in get_thread_regcache (thread=0x0, fetch=1) at
src/gdb/gdbserver/regcache.c:31
     31        regcache = (struct regcache *) inferior_regcache_data (thread);
     (gdb) bt
     #0  0x0000000000406ab6 in inferior_regcache_data (inferior=0x0) at
src/gdb/gdbserver/inferiors.c:236
     #1  0x0000000000406d7f in get_thread_regcache (thread=0x0, fetch=1) at
src/gdb/gdbserver/regcache.c:31
     #2  0x0000000000409271 in prepare_resume_reply (buf=0x20dd593 "",
ptid=..., status=0x20edce0) at src/gdb/gdbserver/remote-utils.c:1147
     #3  0x000000000040ab0a in vstop_notif_reply (event=0x20edcc0,
own_buf=0x20dd590 "T05") at src/gdb/gdbserver/server.c:183
     #4  0x0000000000426b38 in notif_write_event (notif=0x66e6c0 <notif_stop>,
own_buf=0x20dd590 "T05") at src/gdb/gdbserver/notif.c:69
     #5  0x0000000000426c55 in handle_notif_ack (own_buf=0x20dd590 "T05",
packet_len=8) at src/gdb/gdbserver/notif.c:113
     #6  0x000000000041118f in handle_v_requests (own_buf=0x20dd590 "T05",
packet_len=8, new_packet_len=0x7fff742c77b8)
         at src/gdb/gdbserver/server.c:2862
     #7  0x0000000000413850 in process_serial_event () at
src/gdb/gdbserver/server.c:4148
     #8  0x0000000000413945 in handle_serial_event (err=0, client_data=0x0) at
src/gdb/gdbserver/server.c:4196
     #9  0x000000000041a1ef in handle_file_event (event_file_desc=5) at
src/gdb/gdbserver/event-loop.c:429
     #10 0x00000000004199b6 in process_event () at
src/gdb/gdbserver/event-loop.c:184
     #11 0x000000000041a735 in start_event_loop () at
src/gdb/gdbserver/event-loop.c:547
     #12 0x00000000004123d2 in captured_main (argc=4, argv=0x7fff742c7ac8) at
src/gdb/gdbserver/server.c:3562
     #13 0x000000000041252e in main (argc=4, argv=0x7fff742c7ac8) at
src/gdb/gdbserver/server.c:3631

    Clearly this means that a thread pushed a stop reply in the event
    queue, and then before GDB confused the event, the whole process died,
    along with its thread.  But the pending thread event was left
    dangling.  When GDB fetched that event, gdbserver looked up the
    corresponding thread, but found NULL; not expecting this, gdbserver
    crashes when it tries to read this thread's registers.

    gdb/gdbserver/
    2015-08-21  Pedro Alves  <palves@redhat.com>

        PR gdb/18749
        * inferiors.c (remove_thread): Discard any pending stop reply for
        this thread.
        * server.c (remove_all_on_match_pid): Rename to ...
        (remove_all_on_match_ptid): ... this.  Work with a filter ptid
        instead of a pid.
        (discard_queued_stop_replies): Change parameter to a ptid.  Now
        extern.
        (handle_v_kill, kill_inferior_callback)
        (process_serial_event): Adjust.
        (captured_main): Call initialize_notif before starting the
        program, thus before threads are created.
        * server.h (discard_queued_stop_replies): Declare.

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