Re: [patch 02/10] Linux Kernel Markers, architecture independent code.

Alexey Dobriyan
2007-05-10T19:00:22Z

On Thu, May 10, 2007 at 09:12:41AM -0400, Mathieu Desnoyers wrote:
> Linux Kernel Markers - Architecture Independant Code fix 2
>
> Fix trivial SMP bug in list_modules.

> --- linux-2.6-lttng.orig/kernel/module.c 2007-05-10 08:51:02.000000000 -0400
> +++ linux-2.6-lttng/kernel/module.c 2007-05-10 08:51:06.000000000 -0400
> @@ -2657,13 +2657,16 @@
> /* Enumerate loaded modules */
> struct list_head *i;
> struct module *mod;
> - unsigned long refcount = 0;
> + unsigned long refcount;
> + int cpu;
>
> mutex_lock(&module_mutex);
> list_for_each(i, &modules) {
> mod = list_entry(i, struct module, list);
> + refcount = 0;
> #ifdef CONFIG_MODULE_UNLOAD
> - refcount = local_read(&mod->ref[0].count);
> + for_each_online_cpu(cpu)
> + refcount += local_read(&mod->ref[cpu].count);
> #endif //CONFIG_MODULE_UNLOAD

Still wrong: module_get on cpu X, cpu X hot unplugged. There is
module_refcount() for you.