FreeChainXenon/binutils-gdb
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[gdb/symtab] Make per_cu->m_lang atomic

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When building gdb with -fsanitize=thread and running test-case
gdb.dwarf2/inlined_subroutine-inheritance.exp, we run into a data race
between:
...
  Read of size 1 at 0x7b2000003010 by thread T4:
    #0 packed<language, 1ul>::operator language() const packed.h:54
    #1 dwarf2_per_cu_data::set_lang(language) read.h:363
...
and:
...
  Previous write of size 1 at 0x7b2000003010 by main thread:
    #0 dwarf2_per_cu_data::set_lang(language) read.h:365
...

Fix this by making per_cu->m_lang atomic.

Tested on x86_64-linux.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29286
This commit is contained in:
Tom de Vries 2022-07-14 08:19:00 +02:00
parent b35bd7d552
commit 14dd1080c6
1 changed files with 13 additions and 9 deletions
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22
gdb/dwarf2/read.h
View file

@ -181,7 +181,7 @@ private:
std::atomic<packed<dwarf_unit_type, 1>> m_unit_type {(dwarf_unit_type)0};
/* The language of this CU. */
packed<language, LANGUAGE_BYTES> m_lang = language_unknown;
std::atomic<packed<language, LANGUAGE_BYTES>> m_lang {language_unknown};
public:
/* True if this CU has been scanned by the indexer; false if
@ -351,21 +351,25 @@ public:
enum language lang (bool strict_p = true) const
{
enum language l = m_lang.load ();
if (strict_p)
gdb_assert (m_lang != language_unknown);
return m_lang;
gdb_assert (l != language_unknown);
return l;
}
void set_lang (enum language lang)
{
if (unit_type () == DW_UT_partial)
return;
if (m_lang == language_unknown)
/* Set if not set already. */
m_lang = lang;
else
/* If already set, verify that it's the same value. */
gdb_assert (m_lang == lang);
/* Set if not set already. */
packed<language, LANGUAGE_BYTES> nope = language_unknown;
if (m_lang.compare_exchange_strong (nope, lang))
return;
/* If already set, verify that it's the same value. */
nope = lang;
if (m_lang.compare_exchange_strong (nope, lang))
return;
gdb_assert_not_reached ();
}
/* Free any cached file names. */