[Bug symtab/30837] New: [gdb/symtab, index-cache] data race on current_inferior_

[Bug symtab/30837] New: [gdb/symtab, index-cache] data race on current_inferior_

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30837

            Bug ID: 30837
           Summary: [gdb/symtab, index-cache] data race on
                    current_inferior_
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: symtab
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

Created attachment 15106
  --> https://sourceware.org/bugzilla/attachment.cgi?id=15106&action=edit
gdb.log

When building gdb with -fsanitize=threads and using soon to be submitted target
board cc-with-index-cache, I run into a data race in test-case
gdb.ada/non-ascii-utf-8.exp
...
==================^M
^[[1m^[[31mWARNING: ThreadSanitizer: data race (pid=25220)^M
^[[1m^[[0m^[[1m^[[34m  Read of size 8 at 0x000003342928 by thread T12:^M
^[[1m^[[0m    #0 gdb::ref_ptr<inferior, refcounted_object_ref_policy>::get()
const /data/vries/gdb/src/gdb/../gdbsupport/gdb_ref_ptr.h:132 (gdb+0xa690b8)^M
    #1 current_inferior() /data/vries/gdb/src/gdb/inferior.c:57
(gdb+0xa63b74)^M
    #2 target_supports_terminal_ours() /data/vries/gdb/src/gdb/target.c:1121
(gdb+0xfaefd4)^M
    #3 vwarning(char const*, __va_list_tag*)
/data/vries/gdb/src/gdb/utils.c:147 (gdb+0x10e54c5)^M
    #4 warning(char const*, ...) /data/vries/gdb/src/gdbsupport/errors.cc:34
(gdb+0x1dc04e4)^M
    #5 ada_encode_1 /data/vries/gdb/src/gdb/ada-lang.c:1000 (gdb+0x47d348)^M
    #6 ada_encode[abi:cxx11](char const*, bool)
/data/vries/gdb/src/gdb/ada-lang.c:1159 (gdb+0x47dd12)^M
    #7 write_cooked_index /data/vries/gdb/src/gdb/dwarf2/index-write.c:1142
(gdb+0x832e42)^M
    #8 write_gdbindex /data/vries/gdb/src/gdb/dwarf2/index-write.c:1236
(gdb+0x83348b)^M
  ...
^M
^[[1m^[[34m  Previous write of size 8 at 0x000003342928 by main thread:^M
^[[1m^[[0m    #0 gdb::ref_ptr<inferior,
refcounted_object_ref_policy>::reset(inferior*)
/data/vries/gdb/src/gdb/../gdbsupport/gdb_ref_ptr.h:125 (gdb+0xa6a2bf)^M
    #1 gdb::ref_ptr<inferior,
refcounted_object_ref_policy>::operator=(gdb::ref_ptr<inferior,
refcounted_object_ref_policy>&&)
/data/vries/gdb/src/gdb/../gdbsupport/gdb_ref_ptr.h:113 (gdb+0xa691cc)^M
    #2 set_current_inferior(inferior*) /data/vries/gdb/src/gdb/inferior.c:66
(gdb+0xa63bf6)^M
    #3 switch_to_inferior_no_thread(inferior*)
/data/vries/gdb/src/gdb/inferior.c:714 (gdb+0xa66df9)^M
    #4 scoped_restore_current_thread::restore()
/data/vries/gdb/src/gdb/thread.c:1397 (gdb+0xfe1f9b)^M
    #5 scoped_restore_current_thread::~scoped_restore_current_thread()
/data/vries/gdb/src/gdb/thread.c:1415 (gdb+0xfe20c9)^M
    #6
scoped_restore_current_pspace_and_thread::~scoped_restore_current_pspace_and_thread()
/data/vries/gdb/src/gdb/progspace-and-thread.h:29 (gdb+0x628ef7)^M
    #7 bp_loc_is_permanent /data/vries/gdb/src/gdb/breakpoint.c:8532
(gdb+0x609bed)^M
    #8 code_breakpoint::add_location(symtab_and_line const&)
/data/vries/gdb/src/gdb/breakpoint.c:8509 (gdb+0x609acc)^M
    #9 internal_breakpoint::internal_breakpoint(gdbarch*, bptype, unsigned
long) /data/vries/gdb/src/gdb/breakpoint.c:350 (gdb+0x6282a3)^M
    #10 create_internal_breakpoint /data/vries/gdb/src/gdb/breakpoint.c:3454
(gdb+0x5f71c0)^M
    #11 create_internal_breakpoint /data/vries/gdb/src/gdb/breakpoint.c:3485
(gdb+0x5f7346)^M
    #12 create_exception_master_breakpoint_hook
/data/vries/gdb/src/gdb/breakpoint.c:3856 (gdb+0x5f86dc)^M
    #13 create_exception_master_breakpoint
/data/vries/gdb/src/gdb/breakpoint.c:3882 (gdb+0x5f8899)^M
    #14 breakpoint_re_set() /data/vries/gdb/src/gdb/breakpoint.c:13262
(gdb+0x61c3f1)^M
    #15 symbol_file_command(char const*, int)
/data/vries/gdb/src/gdb/symfile.c:1686 (gdb+0xf44c8d)^M
    #16 file_command /data/vries/gdb/src/gdb/exec.c:554 (gdb+0x94f99f)^M
...

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug symtab/30837] [gdb/symtab, index-cache] data race on current_inferior_

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30837

--- Comment #1 from Sourceware Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f1b8ee6f2b4381bc46a0ad4c233b6eddc1e135b5

commit f1b8ee6f2b4381bc46a0ad4c233b6eddc1e135b5
Author: Tom de Vries <tdevries@suse.de>
Date:   Mon Nov 27 21:15:26 2023 +0100

    [gdb/testsuite] Add boards/cc-with-index-cache.exp

    We have a target board cc-with-gdb-index that uses the gdb-add-index script
to
    add a .gdb_index index to an exec.

    There is however an alternative way of adding a .gdb_index: the
index-cache.

    Add a new target board cc-with-index-cache.

    This is not superfluous for two reasons:
    - there is functionality that gdb-add-index doesn't support, but the
      index-cache does: the index-cache can add an index to an exec with a
      .gnu_debugaltlink (note that when using the cc-with-gdb-index board this
      case is quietly ignored), and
    - using the index-cache is excercised in only a few test-cases, and having
      this target board extends the test coverage to the entire test suite. 
This
      is for instance relevant because the index-cache is written by a worker
      thread in the background, so we can check more thoroughly for data races
      (see PR symtab/30837).

    Tested on x86_64-linux.

    Shell script changes checked with shellcheck.

    Approved-By: Tom Tromey <tom@tromey.com>

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug symtab/30837] [gdb/symtab, index-cache] data race on current_inferior_

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30837

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org
           Assignee|unassigned at sourceware dot org   |tromey at sourceware dot org

--- Comment #2 from Tom Tromey <tromey at sourceware dot org> ---
Probably need to defer warnings in this code.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug symtab/30837] [gdb/symtab, index-cache] data race on current_inferior_

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30837

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |29366


Referenced Bugs:

https://sourceware.org/bugzilla/show_bug.cgi?id=29366
[Bug 29366] [meta] New DWARF indexer meta bug
-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug symtab/30837] [gdb/symtab, index-cache] data race on current_inferior_

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30837

--- Comment #3 from Tom Tromey <tromey at sourceware dot org> ---
Also worth noting that if/when the .debug_names writer is fixed,
this warning will be impossible, because that will just be
writing out the DW_AT_name values verbatim.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug symtab/30837] [gdb/symtab, index-cache] data race on current_inferior_

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30837

--- Comment #4 from Tom Tromey <tromey at sourceware dot org> ---
Actually the debug-names writer shouldn't be invoked from the
background so this must be something else.

-- 
You are receiving this mail because:
You are on the CC list for the bug.