[PATCH][NETNS] Cleanup list walking in setup_net and cleanup_net
I proposed introducing a list_for_each_entry_continue_reverse macro to be used in setup_net() when unrolling the failed ->init callback. Here is the macro and some more cleanup in the setup_net() itself to remove one variable from the stack :) The same thing is for the cleanup_net() - the existing list_for_each_entry_reverse() is used. Minor, but the code looks nicer. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> --- diff --git a/include/linux/list.h b/include/linux/list.h index f29fc9c..ad9dcb9 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -525,6 +525,20 @@ static inline void list_splice_init_rcu( pos = list_entry(pos->member.next, typeof(*pos), member)) /** + * list_for_each_entry_continue_reverse - iterate backwards from the given point + * @pos: the type * to use as a loop cursor. + * @head: the head for your list. + * @member: the name of the list_struct within the struct. + * + * Start to iterate over list of given type backwards, continuing after + * the current position. + */ +#define list_for_each_entry_continue_reverse(pos, head, member) \ + for (pos = list_entry(pos->member.prev, typeof(*pos), member); \ + prefetch(pos->member.prev), &pos->member != (head); \ + pos = list_entry(pos->member.prev, typeof(*pos), member)) + +/** * list_for_each_entry_from - iterate over list of given type from the current point * @pos: the type * to use as a loop cursor. * @head: the head for your list. diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 1fc513c..0e6cb02 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -56,7 +56,6 @@ static void net_free(struct net *net) static void cleanup_net(struct work_struct *work) { struct pernet_operations *ops; - struct list_head *ptr; struct net *net; net = container_of(work, struct net, work); @@ -69,8 +68,7 @@ static void cleanup_net(struct work_stru net_unlock(); /* Run all of the network namespace exit methods */ - list_for_each_prev(ptr, &pernet_list) { - ops = list_entry(ptr, struct pernet_operations, list); + list_for_each_entry_reverse(ops, &pernet_list, list) { if (ops->exit) ops->exit(net); } @@ -102,7 +100,6 @@ static int setup_net(struct net *net) { /* Must be called with net_mutex held */ struct pernet_operations *ops; - struct list_head *ptr; int error; memset(net, 0, sizeof(struct net)); @@ -110,8 +107,7 @@ static int setup_net(struct net *net) atomic_set(&net->use_count, 0); error = 0; - list_for_each(ptr, &pernet_list) { - ops = list_entry(ptr, struct pernet_operations, list); + list_for_each_entry(ops, &pernet_list, list) { if (ops->init) { error = ops->init(net); if (error < 0) @@ -120,12 +116,12 @@ static int setup_net(struct net *net) } out: return error; + out_undo: /* Walk through the list backwards calling the exit functions * for the pernet modules whose init functions did not fail. */ - for (ptr = ptr->prev; ptr != &pernet_list; ptr = ptr->prev) { - ops = list_entry(ptr, struct pernet_operations, list); + list_for_each_entry_continue_reverse(ops, &pernet_list, list) { if (ops->exit) ops->exit(net); }
Re: [PATCH][NETNS] Cleanup list walking in setup_net and cleanup_net
From: Pavel Emelyanov <xemul@openvz.org> Date: Tue, 18 Sep 2007 12:06:53 +0400 > I proposed introducing a list_for_each_entry_continue_reverse macro > to be used in setup_net() when unrolling the failed ->init callback. > > Here is the macro and some more cleanup in the setup_net() itself > to remove one variable from the stack :) The same thing is for the > cleanup_net() - the existing list_for_each_entry_reverse() is used. > > Minor, but the code looks nicer. > > Signed-off-by: Pavel Emelyanov <xemul@openvz.org> > Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Applied, thanks Pavel.