Re: [libvirt] [libvirt-python PATCH 03/23] remove useless check for NULL before Py_XDECREF
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(a)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??
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;
>