[Bug gdb/29286] New: SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[Bug gdb/29286] New: SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

            Bug ID: 29286
           Summary: SUMMARY: ThreadSanitizer: data race
                    gdb/dwarf2/read.c:4100 in
                    dw_expand_symtabs_matching_file_matcher
           Product: gdb
           Version: 12.1
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

Created attachment 14168
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14168&action=edit
gdb.log

I build gdb with -fsanitizer=thread and gcc 7.5.0, using patches:
- https://sourceware.org/pipermail/gdb-patches/2022-June/190336.html
- https://sourceware.org/pipermail/gdb-patches/2022-June/190337.html

The latter is not necessary when using gcc 8 or later.  I'm guessing the former
is not necessary on a PIE-by-default system.

When running the testsuite, I run into:
...
FAIL: gdb.ada/access_to_packed_array.exp: maint expand-symtabs
...

Due to:
...
SUMMARY: ThreadSanitizer: data race
/home/vries/gdb_versions/devel/src/gdb/dwarf2/read.c:4100 in
dw_expand_symtabs_matching_file_matcher^
...
See gdb.log attachement for more detail.

I see just one FAIL sofar, but the problem seems to be quite common:
...
$ grep -c "SUMMARY: ThreadSanitizer" gdb.log
253
...

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

Tom de Vries <vries at gcc dot gnu.org> changed:

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

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|12.1                        |HEAD

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
So in dw_expand_symtabs_matching_file_matcher we do:
...
      per_cu->mark = 0;
...
and in cooked_index::do_finalize:
...
      if ((entry->per_cu->lang != language_cplus
           && entry->per_cu->lang != language_ada)
          || (entry->flags & IS_LINKAGE) != 0)
        entry->canonical = entry->name;
...
and in read.h, definition struct dwarf2_per_cu_data we have:
...
  /* A temporary mark bit used when iterating over all CUs in                   
     expand_symtabs_matching.  */
  unsigned int mark : 1;
...
and:
...
  /* The language of this CU.  */
  ENUM_BITFIELD (language) lang : LANGUAGE_BITS;
...
so members of the same bitfield.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
FWIW, I've also compiled with gcc-12, and verified that gdb has a dependency on
the libtsan from the package libtsan2-gcc12, and I still run into the same
issue.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14169
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14169&action=edit
gdb.log (bitfields eliminated in dwarf2_per_cu_data)

After making all the bitfields in the struct proper fields, we run into a
different problem.

We have a race between prepare_one_comp_unit gdb/dwarf2/read.c:23527:
...
    cu->per_cu->lang = dwarf_lang_to_enum_language (attr->constant_value (0));
...
and :
...
cooked_index::do_finalize gdb/dwarf2/cooked-index.c:199:
...
      if ((entry->per_cu->lang != language_cplus
           && entry->per_cu->lang != language_ada)
          || (entry->flags & IS_LINKAGE) != 0)
...

Hmm, AFAIU, building with 0 worker threads would guarantee this order, so the
entry->per_cu->lang will then always be unknown when tested in cooked-index?

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #3)
> Hmm, AFAIU, building with 0 worker threads would guarantee this order, so
> the entry->per_cu->lang will then always be unknown when tested in
> cooked-index?

Not quite.  When building with 0 worker threads, I observed the following
order:
- prepare_one_comp_unit is called for the first time, and
  cu->per_cu->language is set
- in cooked_index::do_finalize, the cu->per_cu->language field is read
- then prepare_one_comp_unit is called once more, overwriting the
  cu->per_cu->language field with the same value

AFAICT, the race condition that thread sanitizer complains about is that the
second write happens after the read, but could happen before it.

I've tried only setting the the cu->per_cu->lang field if it's unknown, and
that seems to fix this particular problem.

But when re-introducing the bitfields, the original problem reappears.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #5 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Tom de Vries from comment #1)
> So in dw_expand_symtabs_matching_file_matcher we do:
> ...
>       per_cu->mark = 0;
> ...
> and in cooked_index::do_finalize:

I think probably cooked_index_functions::expand_symtabs_matching
should wait for finalization to be done.

> When building with 0 worker threads

You can "maint set worker-threads 0"

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14170
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14170&action=edit
Tentative patch

(In reply to Tom Tromey from comment #5)
> (In reply to Tom de Vries from comment #1)
> > So in dw_expand_symtabs_matching_file_matcher we do:
> > ...
> >       per_cu->mark = 0;
> > ...
> > and in cooked_index::do_finalize:
> 
> I think probably cooked_index_functions::expand_symtabs_matching
> should wait for finalization to be done.
> 

I gave this a try, it works for the example, now testing.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14171
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14171&action=edit
gdb.log

While testing, found another one.

Replicating the same fix works for the test-case:
...
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 6e581a6a8ea..f1a5b71b66e 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -4280,6 +4280,11 @@
dwarf2_base_index_functions::find_pc_sect_compunit_symtab
     warning (_("(Internal error: pc %s in read in CU, but not in symtab.)"),
             paddress (objfile->arch (), pc));

+  cooked_index_vector *table
+    = (static_cast<cooked_index_vector *>
+       (per_objfile->per_bfd->index_table.get ()));
+  table->wait ();
+
   result = recursively_find_pc_sect_compunit_symtab
     (dw2_instantiate_symtab (data, per_objfile, false), pc);

...

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #8 from Tom Tromey <tromey at sourceware dot org> ---
Patch looks good, I wrote essentially the same one but then
didn't have time to upload it earlier.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #9 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Tom de Vries from comment #7)
> Created attachment 14171 [details]
> gdb.log
> 
> While testing, found another one.
> 
> Replicating the same fix works for the test-case:
> ...
> diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
> index 6e581a6a8ea..f1a5b71b66e 100644
> --- a/gdb/dwarf2/read.c
> +++ b/gdb/dwarf2/read.c
> @@ -4280,6 +4280,11 @@
> dwarf2_base_index_functions::find_pc_sect_compunit_symtab
>      warning (_("(Internal error: pc %s in read in CU, but not in symtab.)"),
>              paddress (objfile->arch (), pc));
>  
> +  cooked_index_vector *table
> +    = (static_cast<cooked_index_vector *>
> +       (per_objfile->per_bfd->index_table.get ()));
> +  table->wait ();
> +
>    result = recursively_find_pc_sect_compunit_symtab
>      (dw2_instantiate_symtab (data, per_objfile, false), pc);

This will probably have to be a new override method in
cooked_index_functions that waits and then calls the
superclass method.  The base functions can't assume
there is a cooked index.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #14170|0                           |1
        is obsolete|                            |

--- Comment #10 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14172
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14172&action=edit
Tentative patch, updated

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #11 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14173
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14173&action=edit
gdb.log (gdb.dwarf2/dw2-symtab-includes.exp)

Another one.

A data race between is_dwz in dwarf2_find_containing_comp_unit:
...
      if (mid_cu->is_dwz > offset_in_dwz
          || (mid_cu->is_dwz == offset_in_dwz
              && mid_cu->sect_off + mid_cu->length > sect_off))
...
and again lang in prepare_one_comp_unit:
...
    cu->per_cu->lang = dwarf_lang_to_enum_language (attr->constant_value (0));
...

Not sure how to fix this yet.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #12 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #10)
> Created attachment 14172 [details]
> Tentative patch, updated

Hm, the find_pc_sect_compunit_symtab bit causes regressions in test-cases
gdb.dwarf2/dwzbuildid.exp and gdb.dwarf2/dw2-error.exp.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #14172|0                           |1
        is obsolete|                            |

--- Comment #13 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14174
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14174&action=edit
WIP patch

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #14 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14175
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14175&action=edit
gdb.log (gdb.dwarf2/dwz.exp)

AFAIU, the test-case contains (PU: Partial unit, CU: Compilation Unit):
- PU A
- CU B
- CU C importing PU A

A parallel for is called, which starts calling process_psymtab_comp_unit in
threads for A, B and C in parallel.

In the main thread, CU C is handled, the import is encountered,
cooked_indexer::index_imported_unit is called, then
cooked_indexer::ensure_cu_exists, which calls process_psymtab_comp_unit for PU
A, which calls cutu_reader::cutu_reader for PU A.

In thread T3, PU A is handled, and cutu_reader::cutu_reader is called for PU A.

The thread sanitizer then detects that we're trying to read/write
this_cu->dwarf_version in the same PU from different threads, and errors out.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #15 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 14180
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14180&action=edit
Patch fixing all detected data races

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #16 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #15)
> Created attachment 14180 [details]
> Patch fixing all detected data races

[gdb/symtab] Fix some data races

Fix some data races reported by thread sanitizer.

When build with -fsanitize=thread and gcc 12, passes testsuite with no
data races.

There are a few problems when testing:
- we have a heap-use-after-free in gdb.dwarf2/dw2-icc-opaque.exp, but
  that's a known issue, also triggers with -fsanitize-address.
  Reported at PR25723 comment 1.
- we run into timeouts in test-cases gdb.gdb/python-helper.exp and
  gdb.threads/detach-step-over.exp, presumably due to sanitizer overhead.
- with all tui test, at the point of calling newterm we run into
  "WARNING: ThreadSanitizer: unlock of an unlocked mutex (or by a wrong
  thread)".  This also happens when first setting "maint set worker-threads
  0", so this doesn't seem to be related to gdb's multi-threading behaviour.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #17 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #16)
> - with all tui test, at the point of calling newterm we run into
>   "WARNING: ThreadSanitizer: unlock of an unlocked mutex (or by a wrong
>   thread)".  This also happens when first setting "maint set worker-threads
>   0", so this doesn't seem to be related to gdb's multi-threading behaviour.

I can reproduce this with a standalone testcase callling newterm, so this is
indeed unrelated to gdb.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #18 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #16)
> - we have a heap-use-after-free in gdb.dwarf2/dw2-icc-opaque.exp, but
>   that's a known issue, also triggers with -fsanitize-address.
>   Reported at PR25723 comment 1.

Filed as PR29295.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #19 from Tom de Vries <vries at gcc dot gnu.org> ---
Submitted RFC:
https://sourceware.org/pipermail/gdb-patches/2022-June/190420.html

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #20 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #17)
> (In reply to Tom de Vries from comment #16)
> > - with all tui test, at the point of calling newterm we run into
> >   "WARNING: ThreadSanitizer: unlock of an unlocked mutex (or by a wrong
> >   thread)".  This also happens when first setting "maint set worker-threads
> >   0", so this doesn't seem to be related to gdb's multi-threading behaviour.
> 
> I can reproduce this with a standalone testcase callling newterm, so this is
> indeed unrelated to gdb.

Handled at https://sourceware.org/bugzilla/show_bug.cgi?id=29328

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

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
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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #21 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #14)
> Created attachment 14175 [details]
> gdb.log (gdb.dwarf2/dwz.exp)
> 
> AFAIU, the test-case contains (PU: Partial unit, CU: Compilation Unit):
> - PU A
> - CU B
> - CU C importing PU A
> 
> A parallel for is called, which starts calling process_psymtab_comp_unit in
> threads for A, B and C in parallel.
> 
> In the main thread, CU C is handled, the import is encountered,
> cooked_indexer::index_imported_unit is called, then
> cooked_indexer::ensure_cu_exists, which calls process_psymtab_comp_unit for
> PU A, which calls cutu_reader::cutu_reader for PU A.
> 
> In thread T3, PU A is handled, and cutu_reader::cutu_reader is called for PU
> A.
> 
> The thread sanitizer then detects that we're trying to read/write
> this_cu->dwarf_version in the same PU from different threads, and errors out.

https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=33fd0a33639897e1c3403389de882cadd344a494

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #22 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #6)
> Created attachment 14170 [details]
> Tentative patch
> 
> (In reply to Tom Tromey from comment #5)
> > (In reply to Tom de Vries from comment #1)
> > > So in dw_expand_symtabs_matching_file_matcher we do:
> > > ...
> > >       per_cu->mark = 0;
> > > ...
> > > and in cooked_index::do_finalize:
> > 
> > I think probably cooked_index_functions::expand_symtabs_matching
> > should wait for finalization to be done.
> > 
> 
> I gave this a try, it works for the example, now testing.

Submitted as https://sourceware.org/pipermail/gdb-patches/2022-July/190743.html

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #23 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #22)
> (In reply to Tom de Vries from comment #6)
> > Created attachment 14170 [details]
> > Tentative patch
> > 
> > (In reply to Tom Tromey from comment #5)
> > > (In reply to Tom de Vries from comment #1)
> > > > So in dw_expand_symtabs_matching_file_matcher we do:
> > > > ...
> > > >       per_cu->mark = 0;
> > > > ...
> > > > and in cooked_index::do_finalize:
> > > 
> > > I think probably cooked_index_functions::expand_symtabs_matching
> > > should wait for finalization to be done.
> > > 
> > 
> > I gave this a try, it works for the example, now testing.
> 
> Submitted as
> https://sourceware.org/pipermail/gdb-patches/2022-July/190743.html

https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=7d1a572d6b5194d36a96f36b3d28ce591341deb6

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #24 from Tom de Vries <vries at gcc dot gnu.org> ---
There are a couple of "add wait() here" patches mentioned in this PR for which
I can no longer trigger the offending thread sanitizer warning/error.

My understanding of those patches is not good enough to decide that they are
needed anyway, so I'm basically waiting for the next thread sanitizer error to
proceed with this.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #25 from Tom Tromey <tromey at sourceware dot org> ---
What's the state of this bug?
It's on the gdb 13 list, but I'm wondering if the known
issues are fixed.

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[Bug gdb/29286] SUMMARY: ThreadSanitizer: data race gdb/dwarf2/read.c:4100 in dw_expand_symtabs_matching_file_matcher

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29286

--- Comment #26 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #25)
> What's the state of this bug?
> It's on the gdb 13 list, but I'm wondering if the known
> issues are fixed.

The state of this bug is recorded in comment 24.

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