On 09/29/2015 10:29 AM, Pavel Hrdina wrote:
On Sat, Sep 26, 2015 at 09:08:35AM -0400, John Ferlan wrote:
On 09/24/2015 10:01 AM, Pavel Hrdina wrote:
Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- libvirt-override.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/libvirt-override.c b/libvirt-override.c index 14aa0e9..114104b 100644 --- a/libvirt-override.c +++ b/libvirt-override.c @@ -2303,12 +2303,9 @@ libvirt_virRegisterErrorHandler(ATTRIBUTE_UNUSED PyObject * self, pyobj_f);
virSetErrorFunc(NULL, libvirt_virErrorFuncHandler); - if (libvirt_virPythonErrorFuncHandler != NULL) { - Py_XDECREF(libvirt_virPythonErrorFuncHandler); - } - if (libvirt_virPythonErrorFuncCtxt != NULL) { - Py_XDECREF(libvirt_virPythonErrorFuncCtxt); - } + + Py_XDECREF(libvirt_virPythonErrorFuncHandler); + Py_XDECREF(libvirt_virPythonErrorFuncCtxt);
I keep looking at this and thinking why? Why was it added and what is it protecting. Looking at libvirt_virErrorFuncHandler it seems only libvirt_virPythonErrorFuncCtxt gets the Py_XINCREF and that's based on whether libvirt_virPythonErrorFuncHandler is NULL or not.
I don't understand what do you mean by this??
I guess the whole Py_XDECREF usage is still a bit of a mystery. I believe I was trying to consider why someone would have checked for NULL previously. I know from checking it was written that way. But I assume now that if on input it was NULL then nothing happens. No issues otherwise - John
Just feels like something subtle is going on. Also it's a register handler and we're decrementing something that never got incremented.
Check the whole function. It will decrement the old handlers, check for existence of new handlers and clean/set new handlers. And before setting the new handlers, we need to increment them, otherwise they will be cleared by GC.
Everything that is parsed by 'PyArg_ParseTuple' has to be incremented, if you need to use those object outside of the function scope, where you've called that parser.
Pavel
John
if ((pyobj_f == Py_None) && (pyobj_ctx == Py_None)) { libvirt_virPythonErrorFuncHandler = NULL;