Binutils with MCST patches
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Simon Marchi 72bc1d2466 Add missing incref when creating Inferior Python object
The test py-inferior.exp fails when using a debug build of Python 3.6.  I don't
see it failing with my system's default Python, but it might be related to the
different memory allocation scheme used when doing a build with pydebug.

The issue is that we are missing a Py_INCREF in
inferior_to_inferior_object.  The PyObject_New function initializes the
object with a refcount of 1.  If we assume that this refcount
corresponds to the reference we are returning, then we are missing an
incref for the reference in the inferior data.

The counterpart for the incref that corresponds to the reference in the
inferior data is in py_free_inferior, in the form the gdbpy_ref instance.

Here's how I can get it to crash (with some debug output):

  $ ./gdb -nx -ex "set debug python 1"
  (gdb) add-inferior
  Added inferior 2
  (gdb) python infs = gdb.inferiors()
  Creating Python Inferior object inf = 1
  Creating Python Inferior object inf = 2
  (gdb) remove-inferiors 2
  py_free_inferior inf = 2
  infpy_dealloc inf = <unknown>
  (gdb) python infs = None
  Fatal Python error: Objects/tupleobject.c:243 object at 0x7f9cf1a568d8 has negative ref count -1

  Current thread 0x00007f9cf1b68780 (most recent call first):
    File "<string>", line 1 in <module>
  [1]    408 abort (core dumped)  ./gdb -nx -ex "set debug python 1"

After having created the inferiors object, their refcount is 1 (which
comes from PyObject_New), but it should be two.  The gdb inferior object
has a reference and the "infs" list has a reference.

When invoking remove-inferiors, py_free_inferior gets called.  It does
the decref that corresponds to the reference that the gdb inferior
object kept.  At this moment, the refcount drops to 0 and the object
gets deallocated, even though the "infs" list still has a reference.
When we set "infs" to None, Python tries to decref the already zero
refcount and the assert triggers.

With this patch, it looks better:

  (gdb) add-inferior
  Added inferior 2
  (gdb) python infs = gdb.inferiors()
  Creating Python Inferior object inf = 1
  Creating Python Inferior object inf = 2
  (gdb) remove-inferiors 2
  py_free_inferior inf = 2
  (gdb) python infs = None
  infpy_dealloc inf = <unknown>

gdb/ChangeLog:

	* python/py-inferior.c (inferior_to_inferior_object): Increment reference
	count when creating the object.
2017-04-27 17:03:25 -04:00
bfd x86: Create dynamic sections in create_dynamic_sections 2017-04-27 13:55:48 -07:00
binutils Fix PR number in ChangeLog comment. 2017-04-26 15:45:41 +01:00
config picflag.m4 high bit set in comment 2017-01-05 00:02:57 +10:30
cpu Update the openrisc previous program counter (ppc) when running code in the cgen based simulator. 2017-03-20 15:33:51 +00:00
elfcpp Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
etc update-copyright.py for binutils 2017-01-05 00:03:07 +10:30
gas MIPS16/GAS: Factor out duplicate symbol value conversion code 2017-04-27 12:21:58 +01:00
gdb Add missing incref when creating Inferior Python object 2017-04-27 17:03:25 -04:00
gold [GOLD] testsuite/plugin_section_order.c fix 2017-04-27 11:54:29 +09:30
gprof Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
include Handle symbol defined in IR and referenced in DSO 2017-04-20 07:48:35 -07:00
intl Regen intl/configure 2015-08-31 12:53:36 +09:30
ld x86: Create dynamic sections in create_dynamic_sections 2017-04-27 13:55:48 -07:00
libdecnumber Remove leading/trailing white spaces in ChangeLog 2015-07-24 04:16:47 -07:00
libiberty cplus_demangle_fill_component: Handle DEMANGLE_COMPONENT_RVALUE_REFERENCE 2017-03-27 14:18:41 +01:00
opcodes [ARC] Enhance enter/leave mnemonics. 2017-04-25 17:07:00 +02:00
readline Improve MinGW support in Readline 2016-09-17 11:50:37 +03:00
sim Fix ldn/stn multiple instructions. Fix testcases with unaligned data. 2017-04-22 16:36:01 -07:00
texinfo
zlib Sync ZLIB with FSF GCC sources, bringing in version 1.2.11. 2017-02-20 12:52:22 +00:00
.cvsignore
.gitattributes Add a .gitattributes file for use with git-merge-changelog 2014-07-25 18:07:23 -04:00
.gitignore Add archives and make stamps to the .gitignore file. 2016-09-27 15:10:42 +01:00
ChangeLog * config.sub: Sync with master version in config project. 2017-04-13 02:34:19 -07:00
compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in Sync toplevel files with GCC 2015-07-27 07:49:05 -07:00
config.guess Sync top level config files with master versions in the FSF config project. 2017-03-22 14:01:03 +00:00
config.rpath Remove freebsd1 from libtool.m4 macros and config.rpath. 2011-02-13 21:00:14 +00:00
config.sub * config.sub: Sync with master version in config project. 2017-04-13 02:34:19 -07:00
configure Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
configure.ac Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS 2013-01-07 Jeff Johnston <jjohnstn@redhat.com> 2013-01-07 21:39:26 +00:00
COPYING.NEWLIB 2013-10-01 Jeff Johnston <jjohnstn@redhat.com> 2013-10-01 18:14:04 +00:00
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4 Sync top-level btool.m4 with GCC 2016-01-12 08:44:52 -08:00
lt~obsolete.m4
ltgcc.m4
ltmain.sh PR target/59788 2014-02-06 11:01:57 +01:00
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS Update description of ownership of files in include/ 2014-11-04 16:14:14 -08:00
Makefile.def Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
Makefile.in Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
Makefile.tpl Sync top-level make and configure files with FSF GCC mainline versions. 2017-01-23 11:55:48 +00:00
makefile.vms
missing Update from upstream Automake 2014-11-16 13:43:48 +01:00
mkdep
mkinstalldirs Update from upstream Automake 2014-11-16 13:43:48 +01:00
move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
README
README-maintainer-mode
setup.com
src-release.sh fix gdb version parsing in src-release.sh 2016-01-17 10:01:55 +04:00
symlink-tree
ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
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	setenv CC gcc
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