From 0c8a0b88d18d9c8d6cd52bd1a56d6ab88570f287 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Thu, 27 Jul 2023 07:54:18 -0600 Subject: [PATCH] Re-acquire GIL earlier in gdbpy_parse_and_eval MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Tom de Vries filed a bug about an intermittent gdb DAP failure -- and coincidentally, at the same time, Alexandra Hájková sent email about a somewhat similar failure. After looking into this for a while (with no results) using ASan and valgrind, I found that setting PYTHONMALLOC=malloc_debug found the bug instantly. The problem is that gdbpy_parse_and_eval releases the GIL while calling parse_and_eval, but fails to re-acquire it before calling value_to_value_object. This is easily fixed by introducing a new scope. I wonder whether the test suite should unconditionally set PYTHONMALLOC=malloc_debug. Tested-by: Tom de Vries Reviewed-By: Tom de Vries Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30686 --- gdb/python/python.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/gdb/python/python.c b/gdb/python/python.c index 505fc4412d1..6a978d632e9 100644 --- a/gdb/python/python.c +++ b/gdb/python/python.c @@ -994,9 +994,17 @@ gdbpy_parse_and_eval (PyObject *self, PyObject *args, PyObject *kw) PyObject *result = nullptr; try { - gdbpy_allow_threads allow_threads; scoped_value_mark free_values; - struct value *val = parse_and_eval (expr_str, flags); + struct value *val; + { + /* Allow other Python threads to run while we're evaluating + the expression. This is important because the expression + could involve inferior calls or otherwise be a lengthy + calculation. We take care here to re-acquire the GIL here + before continuing with Python work. */ + gdbpy_allow_threads allow_threads; + val = parse_and_eval (expr_str, flags); + } result = value_to_value_object (val); } catch (const gdb_exception &except) -- 2.30.2