[rpms/gdb] gdb-17.2-rebase-f44: Fix python build and re-enable it.

[rpms/gdb] gdb-17.2-rebase-f44: Fix python build and re-enable it.

[Keith Seitz]

            A new commit has been pushed.

            Repo   : rpms/gdb
            Branch : gdb-17.2-rebase-f44
            Commit : 28b99d9981ec195cc7dfedc33f8ec859607af381
            Author : Keith Seitz <keiths@redhat.com>
            Date   : 2020-06-05T15:45:45-07:00
            Stats  : +269/-6 in 7 file(s)
            URL    : https://src.fedoraproject.org/rpms/gdb/c/28b99d9981ec195cc7dfedc33f8ec859607af381?branch=gdb-17.2-rebase-f44

            Log:
            Fix python build and re-enable it.
(RH BZ 1829702, Kevin Buettner and Keith Seitz)

---
diff --git a/_gdb.spec.Patch.include b/_gdb.spec.Patch.include
index 1d8ffd9..917558b 100644
--- a/_gdb.spec.Patch.include
+++ b/_gdb.spec.Patch.include
@@ -400,3 +400,7 @@ Patch098: gdb-rhbz1818011-bfd-gcc10-error.patch
 # Backport fix for deprecation of PyEval_InitThreads in Python 3.9.
 Patch099: gdb-rhbz1822715-fix-python-deprecation.patch
 
+# Backport "Fix Python 3.9 related runtime problems"
+# Kevin Buettner <kevinb@redhat.com> and Keith Seitz <keiths@redhat.com>
+Patch100: gdb-rhbz1829702-fix-python39.patch
+

diff --git a/_gdb.spec.patch.include b/_gdb.spec.patch.include
index dddd45a..fd3cf02 100644
--- a/_gdb.spec.patch.include
+++ b/_gdb.spec.patch.include
@@ -97,3 +97,4 @@
 %patch097 -p1
 %patch098 -p1
 %patch099 -p1
+%patch100 -p1

diff --git a/_patch_order b/_patch_order
index a4377d5..e56faa4 100644
--- a/_patch_order
+++ b/_patch_order
@@ -97,3 +97,4 @@ gdb-vla-intel-fix-print-char-array.patch
 gdb-rhbz1553104-s390x-arch12-test.patch
 gdb-rhbz1818011-bfd-gcc10-error.patch
 gdb-rhbz1822715-fix-python-deprecation.patch
+gdb-rhbz1829702-fix-python39.patch

diff --git a/gdb-rhbz1829702-fix-python39.patch b/gdb-rhbz1829702-fix-python39.patch
new file mode 100644
index 0000000..d4eef56
--- /dev/null
+++ b/gdb-rhbz1829702-fix-python39.patch
@@ -0,0 +1,224 @@
+From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
+From: Keith Seitz <keiths@redhat.com>
+Date: Thu, 4 Jun 2020 17:16:48 -0700
+Subject: gdb-rhbz1829702-fix-python39.patch
+
+;; Backport "Fix Python 3.9 related runtime problems"
+;; Kevin Buettner <kevinb@redhat.com> and Keith Seitz <keiths@redhat.com>
+
+commit c47bae859a5af0d95224d90000df0e529f7c5aa0
+Author: Kevin Buettner <kevinb@redhat.com>
+Date:   Wed May 27 20:05:40 2020 -0700
+
+    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.
+
+diff --git a/gdb/python/python.c b/gdb/python/python.c
+--- a/gdb/python/python.c
++++ b/gdb/python/python.c
+@@ -234,6 +234,30 @@ 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
+@@ -247,6 +271,10 @@ 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 ();
+ }
+ 
+@@ -924,30 +952,6 @@ 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
+ {
+@@ -1548,6 +1552,7 @@ finalize_python (void *ignore)
+ 
+   Py_Finalize ();
+ 
++  gdb_python_initialized = false;
+   restore_active_ext_lang (previous_active);
+ }
+ 
+@@ -1720,8 +1725,7 @@ do_start_initialization ()
+     return false;
+ 
+   /* Release the GIL while gdb runs.  */
+-  PyThreadState_Swap (NULL);
+-  PyEval_ReleaseLock ();
++  PyEval_SaveThread ();
+ 
+   make_final_cleanup (finalize_python, NULL);
+ 

diff --git a/gdb.spec b/gdb.spec
index ace2c59..ec4f2c9 100644
--- a/gdb.spec
+++ b/gdb.spec
@@ -11,9 +11,6 @@
 #                 workload gets run it decreases the general performance now.
 # --define 'scl somepkgname': Independent packages by scl-utils-build.
 
-# https://bugzilla.redhat.com/show_bug.cgi?id=1829702
-%global _without_python 1
-
 %{?scl:%scl_package gdb}
 %{!?scl:
  %global pkg_name %{name}
@@ -38,7 +35,7 @@ Version: 9.1
 
 # The release always contains a leading reserved number, start it at 1.
 # `upstream' is not a part of `name' to stay fully rpm dependencies compatible for the testing.
-Release: 7%{?dist}
+Release: 8%{?dist}
 
 License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ and GPLv2+ with exceptions and GPL+ and LGPLv2+ and LGPLv3+ and BSD and Public Domain and GFDL
 # Do not provide URL for snapshots as the file lasts there only for 2 days.
@@ -1158,6 +1155,10 @@ fi
 %endif
 
 %changelog
+* Fri Jun  5 2020 Keith Seitz <keiths@redhat.com> - 9.1-8
+- Add patch for Python 3.9 and re-enable python.
+- Update generate-*.sh to include stgit support.
+
 * Thu May 21 2020 Miro Hrončok <mhroncok@redhat.com> - 9.1-7
 - Disable Python support to workaround problems with Python 3.9 (RHBZ 1829702)
 

diff --git a/generate-git-repo-from-patches.sh b/generate-git-repo-from-patches.sh
index 490cca9..012480d 100755
--- a/generate-git-repo-from-patches.sh
+++ b/generate-git-repo-from-patches.sh
@@ -14,7 +14,7 @@ usage ()
 $0 -- Generate a git repository from .patch files
 
 Usage:
-  $0 <REPOSITORY>
+  $0 [-u] [-h] <REPOSITORY>
 
 <REPOSITORY> is the directory where the rebase was performed.  You
 need to clone the repository first.
@@ -22,6 +22,7 @@ need to clone the repository first.
 Options are:
 
   -h: Print this message
+  -u: Uncommit all patches and initialize stgit repo
 EOF
     exit 0
 }
@@ -31,8 +32,21 @@ test -f gdb.spec || die "This script needs to run from the same directory as gdb
 test -z $1 && die "You need to specify the repository."
 test "$1" = "-h" && usage
 
+uncommit=0
+if [ "$1" = "-u" ]; then
+    uncommit=1
+    shift
+fi
+
+git_repo=$1
+if [ ! -e $git_repo ]; then
+    echo "$0: repository \"$git_repo\" does not exist"
+    exit 1
+fi
+
 test -f _git_upstream_commit || die "Cannot find _git_upstream_commit file."
 test -f _patch_order || die "Cannot find _patch_order file."
+command -v stg > /dev/null 2>&1  || die "Cannot find stg.  Is stgit installed?"
 
 last_ancestor_commit=`cat _git_upstream_commit`
 
@@ -41,8 +55,19 @@ cd $1
 git name-rev $last_ancestor_commit
 test $? -eq 0 || die "Could not find $last_ancestor_commit in the repository $1.  Did you run 'git fetch'?"
 
-git checkout $last_ancestor_commit
+# Create a branch for the checkout; use the distro name in
+# the name of this branch.
+f=`cd .. && pwd`
+name=devel-`basename $f`
+git checkout -b $name $last_ancestor_commit
+echo "Applying patches..."
 for p in `cat ../_patch_order` ; do
     git am ../$p
     test $? -eq 0 || die "Could not apply patch '$p'."
 done
+
+if (($uncommit)); then
+    echo "Uncommitting patches..."
+    stg init
+    stg uncommit -t $last_ancestor_commit -x
+fi

diff --git a/generate-patches-from-git-repo.sh b/generate-patches-from-git-repo.sh
index f4b3326..c9bc3a9 100755
--- a/generate-patches-from-git-repo.sh
+++ b/generate-patches-from-git-repo.sh
@@ -52,6 +52,13 @@ done
 
 cd $1
 
+# If patches were uncommitted when the patches were applied,
+# make sure that we're sitting at the top-most patch.  Otherwise
+# we'll only add patches up to the current top patch.
+# It's safe to just assume stgit was used -- the push will simply
+# fail.
+stg push --all > /dev/null 2>&1
+
 git name-rev $commit_or_tag
 test $? -eq 0 || die "Could not find $commit_or_tag in the repository.  Did you run 'git fetch'?"