[PATCH 2/8] python: rework netlink callback handling
Arend van Spriel
arend at broadcom.com
Thu Sep 5 08:11:26 EDT 2013
The initial commit adding netlink callback handling also introduced
memory leak issue. The python callback info was stored in an allocated
structure, but that was never freed.
Only exposing nl_cb_alloc() as is. nl_cb_get() is removed as it is
not very useful to use reference counting mechanism. Python uses
that itself internally. To deal properly with Python callback info
the function nl_cb_put() and nl_cb_clone() have a custom wrapper
taking care of Python reference counting.
This commit also adds a Callback python class using the netlink
callback functions.
Signed-off-by: Arend van Spriel <arend at broadcom.com>
---
python/netlink/capi.i | 178 +++++++++++++++++++++++++++++++++++++++++-------
python/netlink/core.py | 29 +++++++-
python/netlink/utils.h | 41 +++++++++++
3 files changed, 221 insertions(+), 27 deletions(-)
create mode 100644 python/netlink/utils.h
diff --git a/python/netlink/capi.i b/python/netlink/capi.i
index 2d2cf0a..785e0a6 100644
--- a/python/netlink/capi.i
+++ b/python/netlink/capi.i
@@ -8,6 +8,8 @@
#include <netlink/cache.h>
#include <netlink/attr.h>
#include <net/if.h>
+
+#include "utils.h"
%}
%include <stdint.i>
@@ -529,8 +531,6 @@ enum nl_cb_type {
extern struct nl_cb *nl_cb_alloc(enum nl_cb_kind);
extern struct nl_cb *nl_cb_clone(struct nl_cb *);
-extern struct nl_cb *nl_cb_get(struct nl_cb *);
-extern void nl_cb_put(struct nl_cb *);
struct nlmsgerr {
int error;
@@ -561,6 +561,52 @@ struct pynl_callback {
PyObject *cba;
};
+struct pynl_cbinfo {
+ struct nl_cb *cb;
+ struct pynl_callback cbtype[NL_CB_TYPE_MAX+1];
+ struct pynl_callback cberr;
+ struct list_head list;
+};
+
+LIST_HEAD(callback_list);
+
+static struct pynl_cbinfo *pynl_find_cbinfo(struct nl_cb *cb, int unlink)
+{
+ struct list_head *pos, *prev;
+ struct pynl_cbinfo *info;
+
+ list_for_each_safe(pos, prev, &callback_list) {
+ info = container_of(pos, struct pynl_cbinfo, list);
+ if (info->cb == cb) {
+ if (unlink)
+ list_del(pos, prev);
+ pynl_dbg("cb=%p: found=%p\n", cb, info);
+ return info;
+ }
+ }
+ pynl_dbg("cb=%p: not found\n", cb);
+ return NULL;
+}
+
+static struct pynl_cbinfo *pynl_get_cbinfo(struct nl_cb *cb, int unlink)
+{
+ struct pynl_cbinfo *info;
+
+ info = pynl_find_cbinfo(cb, unlink);
+
+ if (info || unlink) {
+ /* found or no need to allocate a new one */
+ pynl_dbg("cb=%p: done\n", cb);
+ return info;
+ }
+
+ info = calloc(1, sizeof(*info));
+ info->cb = cb;
+ list_add(&info->list, &callback_list);
+ pynl_dbg("cb=%p: added %p\n", cb, info);
+ return info;
+}
+
static int nl_recv_msg_handler(struct nl_msg *msg, void *arg)
{
struct pynl_callback *cbd = arg;
@@ -610,52 +656,132 @@ static int nl_recv_err_handler(struct sockaddr_nl *nla, struct nlmsgerr *err,
%}
%inline %{
+struct nl_cb *py_nl_cb_clone(struct nl_cb *cb)
+{
+ struct pynl_cbinfo *info, *clone_info;
+ struct nl_cb *clone;
+ int i;
+
+ clone = nl_cb_clone(cb);
+ info = pynl_find_cbinfo(cb, 0);
+ if (info) {
+ clone_info = pynl_get_cbinfo(clone, 0);
+ /* increase refcnt to callback parameters and copy them */
+ for (i = 0; info && i <= NL_CB_TYPE_MAX; i++) {
+ Py_XINCREF(info->cbtype[i].cbf);
+ Py_XINCREF(info->cbtype[i].cba);
+ clone_info->cbtype[i].cbf = info->cbtype[i].cbf;
+ clone_info->cbtype[i].cba = info->cbtype[i].cba;
+ }
+ Py_XINCREF(info->cberr.cbf);
+ Py_XINCREF(info->cberr.cba);
+ clone_info->cberr.cbf = info->cberr.cbf;
+ clone_info->cberr.cba = info->cberr.cba;
+ }
+ return clone;
+}
+
+void py_nl_cb_put(struct nl_cb *cb)
+{
+ struct pynl_cbinfo *info;
+ int i;
+
+ /* obtain callback info (and unlink) */
+ info = pynl_get_cbinfo(cb, 1);
+ pynl_dbg("cb=%p, info=%p\n", cb, info);
+ /* decrease refcnt for callback type handlers */
+ for (i = 0; info && i <= NL_CB_TYPE_MAX; i++) {
+ Py_XDECREF(info->cbtype[i].cbf);
+ Py_XDECREF(info->cbtype[i].cba);
+ }
+ /* decrease refcnt for error handler and free callback info */
+ if (info) {
+ Py_XDECREF(info->cberr.cbf);
+ Py_XDECREF(info->cberr.cba);
+ free(info);
+ }
+ nl_cb_put(cb);
+}
+
int py_nl_cb_set(struct nl_cb *cb, enum nl_cb_type t, enum nl_cb_kind k,
PyObject *func, PyObject *a)
{
- struct pynl_callback *cbd;
-
+ struct pynl_cbinfo *info;
+
+ /* obtain callback info */
+ info = pynl_get_cbinfo(cb, 0);
+
+ /* clear existing handlers (if any) */
+ Py_XDECREF(info->cbtype[t].cbf);
+ Py_XDECREF(info->cbtype[t].cba);
+ info->cbtype[t].cbf = NULL;
+ info->cbtype[t].cba = NULL;
+ pynl_dbg("cb=%p, info=%p, type=%d, kind=%d\n", cb, info, t, k);
+ /* handle custom callback */
if (k == NL_CB_CUSTOM) {
- cbd = calloc(1, sizeof(*cbd));
Py_XINCREF(func);
Py_XINCREF(a);
- cbd->cbf = func;
- cbd->cba = a;
- return nl_cb_set(cb, t, k, nl_recv_msg_handler, cbd);
+ info->cbtype[t].cbf = func;
+ info->cbtype[t].cba = a;
+ return nl_cb_set(cb, t, k,
+ nl_recv_msg_handler, &info->cbtype[t]);
}
- return nl_cb_set(cb, t, k, NULL, NULL);
+ return nl_cb_set(cb, t, k, NULL, NULL);
}
int py_nl_cb_set_all(struct nl_cb *cb, enum nl_cb_kind k,
PyObject *func , PyObject *a)
{
- struct pynl_callback *cbd;
-
- if (k == NL_CB_CUSTOM) {
- cbd = calloc(1, sizeof(*cbd));
- Py_XINCREF(func);
- Py_XINCREF(a);
- cbd->cbf = func;
- cbd->cba = a;
- return nl_cb_set_all(cb, k, nl_recv_msg_handler, cbd);
+ struct pynl_cbinfo *info;
+ int t;
+
+ info = pynl_get_cbinfo(cb, 0);
+ pynl_dbg("cb=%p, info=%p, kind=%d\n", cb, info, k);
+ for (t = 0; t <= NL_CB_TYPE_MAX; t++) {
+ /* (possibly) free existing handler */
+ Py_XDECREF(info->cbtype[t].cbf);
+ Py_XDECREF(info->cbtype[t].cba);
+ info->cbtype[t].cbf = NULL;
+ info->cbtype[t].cba = NULL;
+ if (k == NL_CB_CUSTOM) {
+ Py_XINCREF(func);
+ Py_XINCREF(a);
+ info->cbtype[t].cbf = func;
+ info->cbtype[t].cba = a;
+ }
}
- return nl_cb_set_all(cb, k, NULL, NULL);
+ if (k == NL_CB_CUSTOM)
+ /* callback argument is same for all so using idx 0 here */
+ return nl_cb_set_all(cb, k, nl_recv_msg_handler,
+ &info->cbtype[0]);
+ else
+ return nl_cb_set_all(cb, k, NULL, NULL);
}
int py_nl_cb_err(struct nl_cb *cb, enum nl_cb_kind k,
PyObject *func, PyObject *a)
{
- struct pynl_callback *cbd;
-
+ struct pynl_cbinfo *info;
+
+ /* obtain callback info */
+ info = pynl_get_cbinfo(cb, 0);
+ pynl_dbg("cb=%p, info=%p, kind=%d\n", cb, info, k);
+ /* clear existing handlers (if any) */
+ Py_XDECREF(info->cberr.cbf);
+ Py_XDECREF(info->cberr.cba);
+ info->cberr.cbf = NULL;
+ info->cberr.cba = NULL;
+
+ /* handle custom callback */
if (k == NL_CB_CUSTOM) {
- cbd = calloc(1, sizeof(*cbd));
Py_XINCREF(func);
Py_XINCREF(a);
- cbd->cbf = func;
- cbd->cba = a;
- return nl_cb_err(cb, k, nl_recv_err_handler, cbd);
+ info->cberr.cbf = func;
+ info->cberr.cba = a;
+ return nl_cb_err(cb, k,
+ nl_recv_err_handler, &info->cberr);
}
- return nl_cb_err(cb, k, NULL, NULL);
+ return nl_cb_err(cb, k, NULL, NULL);
}
%}
diff --git a/python/netlink/core.py b/python/netlink/core.py
index 160e2e6..104ba68 100644
--- a/python/netlink/core.py
+++ b/python/netlink/core.py
@@ -10,6 +10,8 @@ This module provides an interface to netlink sockets
The module contains the following public classes:
- Socket -- The netlink socket
+ - Message -- The netlink message
+ - Callback -- The netlink callback handler
- Object -- Abstract object (based on struct nl_obect in libnl) used as
base class for all object types which can be put into a Cache
- Cache -- A collection of objects which are derived from the base
@@ -34,8 +36,9 @@ import sys
import socket
__all__ = [
- 'Message',
'Socket',
+ 'Message',
+ 'Callback',
'DumpParams',
'Object',
'Cache',
@@ -153,6 +156,30 @@ class Message(object):
def send(self, sock):
sock.send(self)
+class Callback(object):
+ """Netlink callback"""
+
+ def __init__(self, kind=capi.NL_CB_DEFAULT):
+ if isinstance(kind, Callback):
+ self._cb = capi.py_nl_cb_clone(kind._cb)
+ else:
+ self._cb = capi.nl_cb_alloc(kind)
+
+ def __del__(self):
+ capi.py_nl_cb_put(self._cb)
+
+ def set_type(self, t, k, handler, obj):
+ return capi.py_nl_cb_set(self._cb, t, k, handler, obj)
+
+ def set_all(self, k, handler, obj):
+ return capi.py_nl_cb_set_all(self._cb, k, handler, obj)
+
+ def set_err(self, k, handler, obj):
+ return capi.py_nl_cb_err(self._cb, k, handler, obj)
+
+ def clone(self):
+ return Callback(self)
+
class Socket(object):
"""Netlink socket"""
diff --git a/python/netlink/utils.h b/python/netlink/utils.h
new file mode 100644
index 0000000..7836c30
--- /dev/null
+++ b/python/netlink/utils.h
@@ -0,0 +1,41 @@
+struct list_head {
+ struct list_head *next;
+};
+
+#define LIST_HEAD(name) \
+ struct list_head name = { &(name) }
+
+static inline int list_empty(const struct list_head *head)
+{
+ return head->next == head;
+}
+
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+ new->next = head->next;
+ head->next = new;
+}
+
+static inline void list_del(struct list_head *entry, struct list_head *prev)
+{
+ prev->next = entry->next;
+ entry->next = entry;
+}
+
+#define list_for_each_safe(pos, n, head) \
+ for (n = (head), pos = (head)->next; pos != (head); \
+ n = pos, pos = n->next)
+
+#undef offsetof
+#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+
+#define container_of(ptr, type, member) ({ \
+ const typeof( ((type *)0)->member ) *__mptr = (ptr); \
+ (type *)( (char *)__mptr - offsetof(type,member) );})
+
+#ifdef DEBUG
+#define pynl_dbg(fmt, ...) \
+ fprintf(stderr, "%s: " fmt, __func__, __VA_ARGS__)
+#else
+#define pynl_dbg(fmt, ...)
+#endif
--
1.7.10.4
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