From a8fe4bbd6b78517f640e25697338b9448c4675c1 Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Thu, 20 Oct 2022 00:31:47 +0200 Subject: gh-98257: Make _PyEval_SetTrace() reentrant (#98258) Make sys.setprofile() and sys.settrace() functions reentrant. They can no long fail with: RuntimeError("Cannot install a trace function while another trace function is being installed"). Make _PyEval_SetTrace() and _PyEval_SetProfile() functions reentrant, rather than detecting and rejecting reentrant calls. Only delete the reference to function arguments once the new function is fully set, when a reentrant call is safe. Call also _PySys_Audit() earlier. --- Python/ceval.c | 57 +++++++++++++-------------------------------------------- 1 file changed, 13 insertions(+), 44 deletions(-) (limited to 'Python/ceval.c') diff --git a/Python/ceval.c b/Python/ceval.c index a112f8bebb..fb8dd48116 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -6343,38 +6343,23 @@ _PyEval_SetProfile(PyThreadState *tstate, Py_tracefunc func, PyObject *arg) /* The caller must hold the GIL */ assert(PyGILState_Check()); - static int reentrant = 0; - if (reentrant) { - _PyErr_SetString(tstate, PyExc_RuntimeError, "Cannot install a profile function " - "while another profile function is being installed"); - reentrant = 0; - return -1; - } - reentrant = 1; - /* Call _PySys_Audit() in the context of the current thread state, even if tstate is not the current thread state. */ PyThreadState *current_tstate = _PyThreadState_GET(); if (_PySys_Audit(current_tstate, "sys.setprofile", NULL) < 0) { - reentrant = 0; return -1; } - PyObject *profileobj = tstate->c_profileobj; - - tstate->c_profilefunc = NULL; - tstate->c_profileobj = NULL; - /* Must make sure that tracing is not ignored if 'profileobj' is freed */ - _PyThreadState_UpdateTracingState(tstate); - Py_XDECREF(profileobj); - - Py_XINCREF(arg); - tstate->c_profileobj = arg; tstate->c_profilefunc = func; - + PyObject *old_profileobj = tstate->c_profileobj; + tstate->c_profileobj = Py_XNewRef(arg); /* Flag that tracing or profiling is turned on */ _PyThreadState_UpdateTracingState(tstate); - reentrant = 0; + + // gh-98257: Only call Py_XDECREF() once the new profile function is fully + // set, so it's safe to call sys.setprofile() again (reentrant call). + Py_XDECREF(old_profileobj); + return 0; } @@ -6416,39 +6401,23 @@ _PyEval_SetTrace(PyThreadState *tstate, Py_tracefunc func, PyObject *arg) /* The caller must hold the GIL */ assert(PyGILState_Check()); - static int reentrant = 0; - - if (reentrant) { - _PyErr_SetString(tstate, PyExc_RuntimeError, "Cannot install a trace function " - "while another trace function is being installed"); - reentrant = 0; - return -1; - } - reentrant = 1; - /* Call _PySys_Audit() in the context of the current thread state, even if tstate is not the current thread state. */ PyThreadState *current_tstate = _PyThreadState_GET(); if (_PySys_Audit(current_tstate, "sys.settrace", NULL) < 0) { - reentrant = 0; return -1; } - PyObject *traceobj = tstate->c_traceobj; - - tstate->c_tracefunc = NULL; - tstate->c_traceobj = NULL; - /* Must make sure that profiling is not ignored if 'traceobj' is freed */ - _PyThreadState_UpdateTracingState(tstate); - Py_XINCREF(arg); - Py_XDECREF(traceobj); - tstate->c_traceobj = arg; tstate->c_tracefunc = func; - + PyObject *old_traceobj = tstate->c_traceobj; + tstate->c_traceobj = Py_XNewRef(arg); /* Flag that tracing or profiling is turned on */ _PyThreadState_UpdateTracingState(tstate); - reentrant = 0; + // gh-98257: Only call Py_XDECREF() once the new trace function is fully + // set, so it's safe to call sys.settrace() again (reentrant call). + Py_XDECREF(old_traceobj); + return 0; } -- cgit v1.2.1