* [Buildroot] [git commit branch/2021.05.x] package/gdb: fix gdb segfault with Python 3.9 support
@ 2021-08-05 11:08 Peter Korsgaard
0 siblings, 0 replies; only message in thread
From: Peter Korsgaard @ 2021-08-05 11:08 UTC (permalink / raw)
To: buildroot
commit: https://git.buildroot.net/buildroot/commit/?id=f57f74c0b923cd021e367ae48692ed232fdd8939
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2021.05.x
When enabling Python 3 support in gdb < 10, gdb segfaults at startup.
The issue is was resolved by the following upstream gdb commit,
present since gdb 10.1:
commit c47bae859a5af0d95224d90000df0e529f7c5aa0
Author: Kevin Buettner <kevinb@redhat.com>
Date: Wed May 27 20:05:40 2020 -0700
Fix Python3.9 related runtime problems
[...]
This commit backports this fix to all relevant gdb versions supported
in Buildroot.
Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 5609c63f0b1b11f4c036c2203b01fa697968d173)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
...01-Fix-Python3.9-related-runtime-problems.patch | 193 ++++++++++++++++++
...07-Fix-Python3.9-related-runtime-problems.patch | 193 ++++++++++++++++++
...07-Fix-Python3.9-related-runtime-problems.patch | 227 +++++++++++++++++++++
3 files changed, 613 insertions(+)
diff --git a/package/gdb/4ecb98fbc2f94dbe01b69384afbc515107de73df/0001-Fix-Python3.9-related-runtime-problems.patch b/package/gdb/4ecb98fbc2f94dbe01b69384afbc515107de73df/0001-Fix-Python3.9-related-runtime-problems.patch
new file mode 100644
index 0000000000..8c2a9d3d5b
--- /dev/null
+++ b/package/gdb/4ecb98fbc2f94dbe01b69384afbc515107de73df/0001-Fix-Python3.9-related-runtime-problems.patch
@@ -0,0 +1,193 @@
+From 8342feee01e4e8d38affcf35e47ad900567f42e0 Mon Sep 17 00:00:00 2001
+From: Kevin Buettner <kevinb@redhat.com>
+Date: Wed, 27 May 2020 20:05:40 -0700
+Subject: [PATCH] Fix Python3.9 related runtime problems
+
+Python3.9b1 is now available on Rawhide. GDB w/ Python 3.9 support
+can be built using the configure switch -with-python=/usr/bin/python3.9.
+
+Attempting to run gdb/Python3.9 segfaults on startup:
+
+ #0 0x00007ffff7b0582c in PyEval_ReleaseLock () from /lib64/libpython3.9.so.1.0
+ #1 0x000000000069ccbf in do_start_initialization ()
+ at worktree-test1/gdb/python/python.c:1789
+ #2 _initialize_python ()
+ at worktree-test1/gdb/python/python.c:1877
+ #3 0x00000000007afb0a in initialize_all_files () at init.c:237
+ ...
+
+Consulting the the documentation...
+
+https://docs.python.org/3/c-api/init.html
+
+...we find that PyEval_ReleaseLock() has been deprecated since version
+3.2. It recommends using PyEval_SaveThread or PyEval_ReleaseThread()
+instead. In do_start_initialization, in gdb/python/python.c, we
+can replace the calls to PyThreadState_Swap() and PyEval_ReleaseLock()
+with a single call to PyEval_SaveThread. (Thanks to Keith Seitz
+for working this out.)
+
+With that in place, GDB gets a little bit further. It still dies
+on startup, but the backtrace is different:
+
+ #0 0x00007ffff7b04306 in PyOS_InterruptOccurred ()
+ from /lib64/libpython3.9.so.1.0
+ #1 0x0000000000576e86 in check_quit_flag ()
+ at worktree-test1/gdb/extension.c:776
+ #2 0x0000000000576f8a in set_active_ext_lang (now_active=now_active@entry=0x983c00 <extension_language_python>)
+ at worktree-test1/gdb/extension.c:705
+ #3 0x000000000069d399 in gdbpy_enter::gdbpy_enter (this=0x7fffffffd2d0,
+ gdbarch=0x0, language=0x0)
+ at worktree-test1/gdb/python/python.c:211
+ #4 0x0000000000686e00 in python_new_inferior (inf=0xddeb10)
+ at worktree-test1/gdb/python/py-inferior.c:251
+ #5 0x00000000005d9fb9 in std::function<void (inferior*)>::operator()(inferior*) const (__args#0=<optimized out>, this=0xccad20)
+ at /usr/include/c++/10/bits/std_function.h:617
+ #6 gdb::observers::observable<inferior*>::notify (args#0=0xddeb10,
+ this=<optimized out>)
+ at worktree-test1/gdb/../gdbsupport/observable.h:106
+ #7 add_inferior_silent (pid=0)
+ at worktree-test1/gdb/inferior.c:113
+ #8 0x00000000005dbcb8 in initialize_inferiors ()
+ at worktree-test1/gdb/inferior.c:947
+ ...
+
+We checked with some Python Developers and were told that we should
+acquire the GIL prior to calling any Python C API function. We
+definitely don't have the GIL for calls of PyOS_InterruptOccurred().
+
+I moved class_gdbpy_gil earlier in the file and use it in
+gdbpy_check_quit_flag() to acquire (and automatically release) the
+GIL.
+
+With those changes in place, I was able to run to a GDB prompt. But,
+when trying to quit, it segfaulted again due to due to some other
+problems with gdbpy_check_quit_flag():
+
+ Thread 1 "gdb" received signal SIGSEGV, Segmentation fault.
+ 0x00007ffff7bbab0c in new_threadstate () from /lib64/libpython3.9.so.1.0
+ (top-gdb) bt 8
+ #0 0x00007ffff7bbab0c in new_threadstate () from /lib64/libpython3.9.so.1.0
+ #1 0x00007ffff7afa5ea in PyGILState_Ensure.cold ()
+ from /lib64/libpython3.9.so.1.0
+ #2 0x000000000069b58c in gdbpy_gil::gdbpy_gil (this=<synthetic pointer>)
+ at worktree-test1/gdb/python/python.c:278
+ #3 gdbpy_check_quit_flag (extlang=<optimized out>)
+ at worktree-test1/gdb/python/python.c:278
+ #4 0x0000000000576e96 in check_quit_flag ()
+ at worktree-test1/gdb/extension.c:776
+ #5 0x000000000057700c in restore_active_ext_lang (previous=0xe9c050)
+ at worktree-test1/gdb/extension.c:729
+ #6 0x000000000088913a in do_my_cleanups (
+ pmy_chain=0xc31870 <final_cleanup_chain>,
+ old_chain=0xae5720 <sentinel_cleanup>)
+ at worktree-test1/gdbsupport/cleanups.cc:131
+ #7 do_final_cleanups ()
+ at worktree-test1/gdbsupport/cleanups.cc:143
+
+In this case, we're trying to call a Python C API function after
+Py_Finalize() has been called from finalize_python(). I made
+finalize_python set gdb_python_initialized to false and then cause
+check_quit_flag() to return early when it's false.
+
+With these changes in place, GDB seems to be working again with
+Python3.9b1. I think it likely that there are other problems lurking.
+I wouldn't be surprised to find that there are other calls into Python
+where we don't first make sure that we have the GIL. Further changes
+may well be needed.
+
+I see no regressions testing on Rawhide using a GDB built with the
+default Python version (3.8.3) versus one built using Python 3.9b1.
+
+I've also tested on Fedora 28, 29, 30, 31, and 32 (all x86_64) using
+the default (though updated) system installed versions of Python on
+those OSes. This means that I've tested against Python versions
+2.7.15, 2.7.17, 2.7.18, 3.7.7, 3.8.2, and 3.8.3. In each case GDB
+still builds without problem and shows no regressions after applying
+this patch.
+
+gdb/ChangeLog:
+
+2020-MM-DD Kevin Buettner <kevinb@redhat.com>
+ Keith Seitz <keiths@redhat.com>
+
+ * python/python.c (do_start_initialization): For Python 3.9 and
+ later, call PyEval_SaveThread instead of PyEval_ReleaseLock.
+ (class gdbpy_gil): Move to earlier in file.
+ (finalize_python): Set gdb_python_initialized.
+ (gdbpy_check_quit_flag): Acquire GIL via gdbpy_gil. Return early
+ when not initialized.
+
+[import into Buildroot, removing ChangeLog change to avoid conflict]
+Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
+---
+ gdb/python/python.c | 32 ++++++++++++++++++++++++++++++--
+ 1 file changed, 30 insertions(+), 2 deletions(-)
+
+diff --git a/gdb/python/python.c b/gdb/python/python.c
+index b00b70be85b..0eee3f0397c 100644
+--- a/gdb/python/python.c
++++ b/gdb/python/python.c
+@@ -268,6 +268,30 @@ ensure_python_env (struct gdbarch *gdbarch,
+ return make_cleanup (restore_python_env, env);
+ }
+
++/* A helper class to save and restore the GIL, but without touching
++ the other globals that are handled by gdbpy_enter. */
++
++class gdbpy_gil
++{
++public:
++
++ gdbpy_gil ()
++ : m_state (PyGILState_Ensure ())
++ {
++ }
++
++ ~gdbpy_gil ()
++ {
++ PyGILState_Release (m_state);
++ }
++
++ DISABLE_COPY_AND_ASSIGN (gdbpy_gil);
++
++private:
++
++ PyGILState_STATE m_state;
++};
++
+ /* Set the quit flag. */
+
+ static void
+@@ -281,6 +305,10 @@ gdbpy_set_quit_flag (const struct extension_language_defn *extlang)
+ static int
+ gdbpy_check_quit_flag (const struct extension_language_defn *extlang)
+ {
++ if (!gdb_python_initialized)
++ return 0;
++
++ gdbpy_gil gil;
+ return PyOS_InterruptOccurred ();
+ }
+
+@@ -1620,6 +1648,7 @@ finalize_python (void *ignore)
+
+ Py_Finalize ();
+
++ gdb_python_initialized = false;
+ restore_active_ext_lang (previous_active);
+ }
+ #endif
+@@ -1854,8 +1883,7 @@ message == an error message without a stack will be printed."),
+ goto fail;
+
+ /* Release the GIL while gdb runs. */
+- PyThreadState_Swap (NULL);
+- PyEval_ReleaseLock ();
++ PyEval_SaveThread ();
+
+ make_final_cleanup (finalize_python, NULL);
+
+--
+2.31.1
+
diff --git a/package/gdb/8.3.1/0007-Fix-Python3.9-related-runtime-problems.patch b/package/gdb/8.3.1/0007-Fix-Python3.9-related-runtime-problems.patch
new file mode 100644
index 0000000000..63cfa1bd3e
--- /dev/null
+++ b/package/gdb/8.3.1/0007-Fix-Python3.9-related-runtime-problems.patch
@@ -0,0 +1,193 @@
+From 51ef4f6ec819259d4a57fa4155ee78700918f8ff Mon Sep 17 00:00:00 2001
+From: Kevin Buettner <kevinb@redhat.com>
+Date: Wed, 27 May 2020 20:05:40 -0700
+Subject: [PATCH] Fix Python3.9 related runtime problems
+
+Python3.9b1 is now available on Rawhide. GDB w/ Python 3.9 support
+can be built using the configure switch -with-python=/usr/bin/python3.9.
+
+Attempting to run gdb/Python3.9 segfaults on startup:
+
+ #0 0x00007ffff7b0582c in PyEval_ReleaseLock () from /lib64/libpython3.9.so.1.0
+ #1 0x000000000069ccbf in do_start_initialization ()
+ at worktree-test1/gdb/python/python.c:1789
+ #2 _initialize_python ()
+ at worktree-test1/gdb/python/python.c:1877
+ #3 0x00000000007afb0a in initialize_all_files () at init.c:237
+ ...
+
+Consulting the the documentation...
+
+https://docs.python.org/3/c-api/init.html
+
+...we find that PyEval_ReleaseLock() has been deprecated since version
+3.2. It recommends using PyEval_SaveThread or PyEval_ReleaseThread()
+instead. In do_start_initialization, in gdb/python/python.c, we
+can replace the calls to PyThreadState_Swap() and PyEval_ReleaseLock()
+with a single call to PyEval_SaveThread. (Thanks to Keith Seitz
+for working this out.)
+
+With that in place, GDB gets a little bit further. It still dies
+on startup, but the backtrace is different:
+
+ #0 0x00007ffff7b04306 in PyOS_InterruptOccurred ()
+ from /lib64/libpython3.9.so.1.0
+ #1 0x0000000000576e86 in check_quit_flag ()
+ at worktree-test1/gdb/extension.c:776
+ #2 0x0000000000576f8a in set_active_ext_lang (now_active=now_active@entry=0x983c00 <extension_language_python>)
+ at worktree-test1/gdb/extension.c:705
+ #3 0x000000000069d399 in gdbpy_enter::gdbpy_enter (this=0x7fffffffd2d0,
+ gdbarch=0x0, language=0x0)
+ at worktree-test1/gdb/python/python.c:211
+ #4 0x0000000000686e00 in python_new_inferior (inf=0xddeb10)
+ at worktree-test1/gdb/python/py-inferior.c:251
+ #5 0x00000000005d9fb9 in std::function<void (inferior*)>::operator()(inferior*) const (__args#0=<optimized out>, this=0xccad20)
+ at /usr/include/c++/10/bits/std_function.h:617
+ #6 gdb::observers::observable<inferior*>::notify (args#0=0xddeb10,
+ this=<optimized out>)
+ at worktree-test1/gdb/../gdbsupport/observable.h:106
+ #7 add_inferior_silent (pid=0)
+ at worktree-test1/gdb/inferior.c:113
+ #8 0x00000000005dbcb8 in initialize_inferiors ()
+ at worktree-test1/gdb/inferior.c:947
+ ...
+
+We checked with some Python Developers and were told that we should
+acquire the GIL prior to calling any Python C API function. We
+definitely don't have the GIL for calls of PyOS_InterruptOccurred().
+
+I moved class_gdbpy_gil earlier in the file and use it in
+gdbpy_check_quit_flag() to acquire (and automatically release) the
+GIL.
+
+With those changes in place, I was able to run to a GDB prompt. But,
+when trying to quit, it segfaulted again due to due to some other
+problems with gdbpy_check_quit_flag():
+
+ Thread 1 "gdb" received signal SIGSEGV, Segmentation fault.
+ 0x00007ffff7bbab0c in new_threadstate () from /lib64/libpython3.9.so.1.0
+ (top-gdb) bt 8
+ #0 0x00007ffff7bbab0c in new_threadstate () from /lib64/libpython3.9.so.1.0
+ #1 0x00007ffff7afa5ea in PyGILState_Ensure.cold ()
+ from /lib64/libpython3.9.so.1.0
+ #2 0x000000000069b58c in gdbpy_gil::gdbpy_gil (this=<synthetic pointer>)
+ at worktree-test1/gdb/python/python.c:278
+ #3 gdbpy_check_quit_flag (extlang=<optimized out>)
+ at worktree-test1/gdb/python/python.c:278
+ #4 0x0000000000576e96 in check_quit_flag ()
+ at worktree-test1/gdb/extension.c:776
+ #5 0x000000000057700c in restore_active_ext_lang (previous=0xe9c050)
+ at worktree-test1/gdb/extension.c:729
+ #6 0x000000000088913a in do_my_cleanups (
+ pmy_chain=0xc31870 <final_cleanup_chain>,
+ old_chain=0xae5720 <sentinel_cleanup>)
+ at worktree-test1/gdbsupport/cleanups.cc:131
+ #7 do_final_cleanups ()
+ at worktree-test1/gdbsupport/cleanups.cc:143
+
+In this case, we're trying to call a Python C API function after
+Py_Finalize() has been called from finalize_python(). I made
+finalize_python set gdb_python_initialized to false and then cause
+check_quit_flag() to return early when it's false.
+
+With these changes in place, GDB seems to be working again with
+Python3.9b1. I think it likely that there are other problems lurking.
+I wouldn't be surprised to find that there are other calls into Python
+where we don't first make sure that we have the GIL. Further changes
+may well be needed.
+
+I see no regressions testing on Rawhide using a GDB built with the
+default Python version (3.8.3) versus one built using Python 3.9b1.
+
+I've also tested on Fedora 28, 29, 30, 31, and 32 (all x86_64) using
+the default (though updated) system installed versions of Python on
+those OSes. This means that I've tested against Python versions
+2.7.15, 2.7.17, 2.7.18, 3.7.7, 3.8.2, and 3.8.3. In each case GDB
+still builds without problem and shows no regressions after applying
+this patch.
+
+gdb/ChangeLog:
+
+2020-MM-DD Kevin Buettner <kevinb@redhat.com>
+ Keith Seitz <keiths@redhat.com>
+
+ * python/python.c (do_start_initialization): For Python 3.9 and
+ later, call PyEval_SaveThread instead of PyEval_ReleaseLock.
+ (class gdbpy_gil): Move to earlier in file.
+ (finalize_python): Set gdb_python_initialized.
+ (gdbpy_check_quit_flag): Acquire GIL via gdbpy_gil. Return early
+ when not initialized.
+
+[import into Buildroot, removing ChangeLog change to avoid conflict]
+Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
+---
+ gdb/python/python.c | 32 ++++++++++++++++++++++++++++++--
+ 1 file changed, 30 insertions(+), 2 deletions(-)
+
+diff --git a/gdb/python/python.c b/gdb/python/python.c
+index c23db2c1261..0b77354630e 100644
+--- a/gdb/python/python.c
++++ b/gdb/python/python.c
+@@ -235,6 +235,30 @@ gdbpy_enter::~gdbpy_enter ()
+ restore_active_ext_lang (m_previous_active);
+ }
+
++/* A helper class to save and restore the GIL, but without touching
++ the other globals that are handled by gdbpy_enter. */
++
++class gdbpy_gil
++{
++public:
++
++ gdbpy_gil ()
++ : m_state (PyGILState_Ensure ())
++ {
++ }
++
++ ~gdbpy_gil ()
++ {
++ PyGILState_Release (m_state);
++ }
++
++ DISABLE_COPY_AND_ASSIGN (gdbpy_gil);
++
++private:
++
++ PyGILState_STATE m_state;
++};
++
+ /* Set the quit flag. */
+
+ static void
+@@ -248,6 +272,10 @@ gdbpy_set_quit_flag (const struct extension_language_defn *extlang)
+ static int
+ gdbpy_check_quit_flag (const struct extension_language_defn *extlang)
+ {
++ if (!gdb_python_initialized)
++ return 0;
++
++ gdbpy_gil gil;
+ return PyOS_InterruptOccurred ();
+ }
+
+@@ -1573,6 +1601,7 @@ finalize_python (void *ignore)
+
+ Py_Finalize ();
+
++ gdb_python_initialized = false;
+ restore_active_ext_lang (previous_active);
+ }
+
+@@ -1736,8 +1765,7 @@ do_start_initialization ()
+ return false;
+
+ /* Release the GIL while gdb runs. */
+- PyThreadState_Swap (NULL);
+- PyEval_ReleaseLock ();
++ PyEval_SaveThread ();
+
+ make_final_cleanup (finalize_python, NULL);
+
+--
+2.31.1
+
diff --git a/package/gdb/9.2/0007-Fix-Python3.9-related-runtime-problems.patch b/package/gdb/9.2/0007-Fix-Python3.9-related-runtime-problems.patch
new file mode 100644
index 0000000000..89b0cdc4a0
--- /dev/null
+++ b/package/gdb/9.2/0007-Fix-Python3.9-related-runtime-problems.patch
@@ -0,0 +1,227 @@
+From c47bae859a5af0d95224d90000df0e529f7c5aa0 Mon Sep 17 00:00:00 2001
+From: Kevin Buettner <kevinb@redhat.com>
+Date: Wed, 27 May 2020 20:05:40 -0700
+Subject: [PATCH] Fix Python3.9 related runtime problems
+
+Python3.9b1 is now available on Rawhide. GDB w/ Python 3.9 support
+can be built using the configure switch -with-python=/usr/bin/python3.9.
+
+Attempting to run gdb/Python3.9 segfaults on startup:
+
+ #0 0x00007ffff7b0582c in PyEval_ReleaseLock () from /lib64/libpython3.9.so.1.0
+ #1 0x000000000069ccbf in do_start_initialization ()
+ at worktree-test1/gdb/python/python.c:1789
+ #2 _initialize_python ()
+ at worktree-test1/gdb/python/python.c:1877
+ #3 0x00000000007afb0a in initialize_all_files () at init.c:237
+ ...
+
+Consulting the the documentation...
+
+https://docs.python.org/3/c-api/init.html
+
+...we find that PyEval_ReleaseLock() has been deprecated since version
+3.2. It recommends using PyEval_SaveThread or PyEval_ReleaseThread()
+instead. In do_start_initialization, in gdb/python/python.c, we
+can replace the calls to PyThreadState_Swap() and PyEval_ReleaseLock()
+with a single call to PyEval_SaveThread. (Thanks to Keith Seitz
+for working this out.)
+
+With that in place, GDB gets a little bit further. It still dies
+on startup, but the backtrace is different:
+
+ #0 0x00007ffff7b04306 in PyOS_InterruptOccurred ()
+ from /lib64/libpython3.9.so.1.0
+ #1 0x0000000000576e86 in check_quit_flag ()
+ at worktree-test1/gdb/extension.c:776
+ #2 0x0000000000576f8a in set_active_ext_lang (now_active=now_active@entry=0x983c00 <extension_language_python>)
+ at worktree-test1/gdb/extension.c:705
+ #3 0x000000000069d399 in gdbpy_enter::gdbpy_enter (this=0x7fffffffd2d0,
+ gdbarch=0x0, language=0x0)
+ at worktree-test1/gdb/python/python.c:211
+ #4 0x0000000000686e00 in python_new_inferior (inf=0xddeb10)
+ at worktree-test1/gdb/python/py-inferior.c:251
+ #5 0x00000000005d9fb9 in std::function<void (inferior*)>::operator()(inferior*) const (__args#0=<optimized out>, this=0xccad20)
+ at /usr/include/c++/10/bits/std_function.h:617
+ #6 gdb::observers::observable<inferior*>::notify (args#0=0xddeb10,
+ this=<optimized out>)
+ at worktree-test1/gdb/../gdbsupport/observable.h:106
+ #7 add_inferior_silent (pid=0)
+ at worktree-test1/gdb/inferior.c:113
+ #8 0x00000000005dbcb8 in initialize_inferiors ()
+ at worktree-test1/gdb/inferior.c:947
+ ...
+
+We checked with some Python Developers and were told that we should
+acquire the GIL prior to calling any Python C API function. We
+definitely don't have the GIL for calls of PyOS_InterruptOccurred().
+
+I moved class_gdbpy_gil earlier in the file and use it in
+gdbpy_check_quit_flag() to acquire (and automatically release) the
+GIL.
+
+With those changes in place, I was able to run to a GDB prompt. But,
+when trying to quit, it segfaulted again due to due to some other
+problems with gdbpy_check_quit_flag():
+
+ Thread 1 "gdb" received signal SIGSEGV, Segmentation fault.
+ 0x00007ffff7bbab0c in new_threadstate () from /lib64/libpython3.9.so.1.0
+ (top-gdb) bt 8
+ #0 0x00007ffff7bbab0c in new_threadstate () from /lib64/libpython3.9.so.1.0
+ #1 0x00007ffff7afa5ea in PyGILState_Ensure.cold ()
+ from /lib64/libpython3.9.so.1.0
+ #2 0x000000000069b58c in gdbpy_gil::gdbpy_gil (this=<synthetic pointer>)
+ at worktree-test1/gdb/python/python.c:278
+ #3 gdbpy_check_quit_flag (extlang=<optimized out>)
+ at worktree-test1/gdb/python/python.c:278
+ #4 0x0000000000576e96 in check_quit_flag ()
+ at worktree-test1/gdb/extension.c:776
+ #5 0x000000000057700c in restore_active_ext_lang (previous=0xe9c050)
+ at worktree-test1/gdb/extension.c:729
+ #6 0x000000000088913a in do_my_cleanups (
+ pmy_chain=0xc31870 <final_cleanup_chain>,
+ old_chain=0xae5720 <sentinel_cleanup>)
+ at worktree-test1/gdbsupport/cleanups.cc:131
+ #7 do_final_cleanups ()
+ at worktree-test1/gdbsupport/cleanups.cc:143
+
+In this case, we're trying to call a Python C API function after
+Py_Finalize() has been called from finalize_python(). I made
+finalize_python set gdb_python_initialized to false and then cause
+check_quit_flag() to return early when it's false.
+
+With these changes in place, GDB seems to be working again with
+Python3.9b1. I think it likely that there are other problems lurking.
+I wouldn't be surprised to find that there are other calls into Python
+where we don't first make sure that we have the GIL. Further changes
+may well be needed.
+
+I see no regressions testing on Rawhide using a GDB built with the
+default Python version (3.8.3) versus one built using Python 3.9b1.
+
+I've also tested on Fedora 28, 29, 30, 31, and 32 (all x86_64) using
+the default (though updated) system installed versions of Python on
+those OSes. This means that I've tested against Python versions
+2.7.15, 2.7.17, 2.7.18, 3.7.7, 3.8.2, and 3.8.3. In each case GDB
+still builds without problem and shows no regressions after applying
+this patch.
+
+gdb/ChangeLog:
+
+2020-MM-DD Kevin Buettner <kevinb@redhat.com>
+ Keith Seitz <keiths@redhat.com>
+
+ * python/python.c (do_start_initialization): For Python 3.9 and
+ later, call PyEval_SaveThread instead of PyEval_ReleaseLock.
+ (class gdbpy_gil): Move to earlier in file.
+ (finalize_python): Set gdb_python_initialized.
+ (gdbpy_check_quit_flag): Acquire GIL via gdbpy_gil. Return early
+ when not initialized.
+
+
+[import into Buildroot, removing ChangeLog change to avoid conflict]
+Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
+
+---
+ gdb/ChangeLog | 10 ++++++++
+ gdb/python/python.c | 56 ++++++++++++++++++++++++---------------------
+ 2 files changed, 40 insertions(+), 26 deletions(-)
+
+diff --git a/gdb/python/python.c b/gdb/python/python.c
+index 67f362b852d..4bdd2201abc 100644
+--- a/gdb/python/python.c
++++ b/gdb/python/python.c
+@@ -238,6 +238,30 @@ gdbpy_enter::~gdbpy_enter ()
+ PyGILState_Release (m_state);
+ }
+
++/* A helper class to save and restore the GIL, but without touching
++ the other globals that are handled by gdbpy_enter. */
++
++class gdbpy_gil
++{
++public:
++
++ gdbpy_gil ()
++ : m_state (PyGILState_Ensure ())
++ {
++ }
++
++ ~gdbpy_gil ()
++ {
++ PyGILState_Release (m_state);
++ }
++
++ DISABLE_COPY_AND_ASSIGN (gdbpy_gil);
++
++private:
++
++ PyGILState_STATE m_state;
++};
++
+ /* Set the quit flag. */
+
+ static void
+@@ -251,6 +275,10 @@ gdbpy_set_quit_flag (const struct extension_language_defn *extlang)
+ static int
+ gdbpy_check_quit_flag (const struct extension_language_defn *extlang)
+ {
++ if (!gdb_python_initialized)
++ return 0;
++
++ gdbpy_gil gil;
+ return PyOS_InterruptOccurred ();
+ }
+
+@@ -943,30 +971,6 @@ gdbpy_source_script (const struct extension_language_defn *extlang,
+
+ /* Posting and handling events. */
+
+-/* A helper class to save and restore the GIL, but without touching
+- the other globals that are handled by gdbpy_enter. */
+-
+-class gdbpy_gil
+-{
+-public:
+-
+- gdbpy_gil ()
+- : m_state (PyGILState_Ensure ())
+- {
+- }
+-
+- ~gdbpy_gil ()
+- {
+- PyGILState_Release (m_state);
+- }
+-
+- DISABLE_COPY_AND_ASSIGN (gdbpy_gil);
+-
+-private:
+-
+- PyGILState_STATE m_state;
+-};
+-
+ /* A single event. */
+ struct gdbpy_event
+ {
+@@ -1616,6 +1620,7 @@ finalize_python (void *ignore)
+
+ Py_Finalize ();
+
++ gdb_python_initialized = false;
+ restore_active_ext_lang (previous_active);
+ }
+
+@@ -1785,8 +1790,7 @@ do_start_initialization ()
+ return false;
+
+ /* Release the GIL while gdb runs. */
+- PyThreadState_Swap (NULL);
+- PyEval_ReleaseLock ();
++ PyEval_SaveThread ();
+
+ make_final_cleanup (finalize_python, NULL);
+
+--
+2.26.3
+
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