Re: [patch] Re: Disable -lmcheck when Python has threads (Re: [BUG] gdb crash when "python import gtk")

[Khoo Yit Phang <khooyp@cs.umd.edu>]

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Hi,

On Aug 30, 2012, at 12:43 PM, Jan Kratochvil wrote:

> On Thu, 30 Aug 2012 18:00:46 +0200, Khoo Yit Phang wrote:
>> 2012-08-30  Khoo Yit Phang  <khooyp@cs.umd.edu>
> 
> This patch does not seem to require copyright assignment but it would be safer
> to complete one for example from Sergio Durigan Junior <sergiodj@redhat.com>.
> Also for any possible future contributions.

I have copyright assignment set up, and commit access.

I've attached a new patch with the following changes: 1) I reverted python-config.py and used a different method to test for threads ("python -m threading"); 2) -lmcheck is not enabled by default when Python is available with reads; and 3) running configure with --enable-lmcheck when Python is available with threads now leads to a warning, rather than disabling -lmcheck.

Thanks,

Yit
August 30, 2012


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# HG changeset patch
# Parent 38ae59cbbba369e1b4bd78b4b2f378e26548b79d
Do not enable -lmcheck by default when Python is enabled with threading support.

gdb/ChangeLog:

2012-08-30  Khoo Yit Phang  <khooyp@cs.umd.edu>

	Do not enable -lmcheck by default when Python is enabled with
	threading support.
	* configure.ac: (python_has_threads) New variable, by testing
	"python -m threading".
	Move --enable-lmcheck after --with-python.
	Do not enable -lmcheck by default if python_has_threads=yes.
	Warn if --enable-lmcheck=yes and python_has_threads=yes.
	* configure: Regenerate.

diff --git a/gdb/configure.ac b/gdb/configure.ac
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -645,28 +645,6 @@
 AC_SUBST(READLINE_CFLAGS)
 AC_SUBST(READLINE_TEXI_INCFLAG)
 
-# Provide a --enable-libmcheck/--disable-libmcheck set of options
-# allowing a user to enable this option even when building releases,
-# or to disable it when building a snapshot.
-AC_ARG_ENABLE(libmcheck,
-  AS_HELP_STRING([--enable-libmcheck],
-                 [Try building GDB with -lmcheck if available]),
-  [case "${enableval}" in
-     yes | y) ENABLE_LIBMCHECK="yes" ;;
-     no | n)  ENABLE_LIBMCHECK="no" ;;
-     *) AC_MSG_ERROR(bad value ${enableval} for --enable-libmcheck) ;;
-   esac])
-
-# Enable -lmcheck by default (it provides cheap-enough memory mangling),
-# but turn it off for releases.
-if test -z "${ENABLE_LIBMCHECK}" && $development; then
-    ENABLE_LIBMCHECK=yes
-fi
-
-if test "$ENABLE_LIBMCHECK" = "yes" ; then
-  AC_CHECK_LIB(mcheck, main)
-fi
-
 # Generate jit-reader.h
 
 # This is typedeffed to GDB_CORE_ADDR in jit-reader.h
@@ -882,6 +860,11 @@
         AC_ERROR(failure running python-config --exec-prefix)
       fi
     fi
+    if ${python_prog} -m threading >/dev/null 2>/dev/null; then
+      python_has_threads=yes
+    else
+      python_has_threads=no
+    fi
   else
     # We do not have a python executable we can use to determine where
     # to find the Python headers and libs.  We cannot guess the include
@@ -890,6 +873,7 @@
     # do except assume that the compiler will be able to find those files.
     python_includes=
     python_libs=
+    python_has_threads=yes
     have_python_config=no
   fi
 
@@ -1028,6 +1012,34 @@
 AC_SUBST(PYTHON_CPPFLAGS)
 AC_SUBST(PYTHON_LIBS)
 
+# Provide a --enable-libmcheck/--disable-libmcheck set of options
+# allowing a user to enable this option even when building releases,
+# or to disable it when building a snapshot.
+AC_ARG_ENABLE(libmcheck,
+  AS_HELP_STRING([--enable-libmcheck],
+                 [Try building GDB with -lmcheck if available]),
+  [case "${enableval}" in
+     yes | y) ENABLE_LIBMCHECK="yes" ;;
+     no | n)  ENABLE_LIBMCHECK="no" ;;
+     *) AC_MSG_ERROR(bad value ${enableval} for --enable-libmcheck) ;;
+   esac])
+
+# Enable -lmcheck by default (it provides cheap-enough memory mangling),
+# but turn it off if Python is enabled with threads, and for releases.
+if test -z "${ENABLE_LIBMCHECK}" \
+        -a \( "${have_libpython}" = "no" \
+	     -o "${python_has_threads}" = "no" \) \
+    && $development; then
+  ENABLE_LIBMCHECK=yes
+fi
+
+if test "$ENABLE_LIBMCHECK" = "yes" ; then
+  if test "${have_libpython}" != "no" -a "${python_has_threads}" = "yes" ; then
+    AC_MSG_WARN(--enable-libmcheck may lead to spurious crashes if threads are used in python)
+  fi
+  AC_CHECK_LIB(mcheck, main)
+fi
+
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