Re: [for-next][PATCH 14/15] tracepoint: Do not fail unregistering a probe due to memory failure

Peter Zijlstra
2021-02-03T17:10:51Z

On Wed, Feb 03, 2021 at 11:05:31AM -0500, Steven Rostedt wrote:
> + if (new) {
> + for (i = 0; old[i].func; i++)
> + if ((old[i].func != tp_func->func
> + || old[i].data != tp_func->data)
> + && old[i].func != tp_stub_func)

logical operators go at the end..

> + new[j++] = old[i];
> + new[nr_probes - nr_del].func = NULL;
> + *funcs = new;
> + } else {
> + /*
> + * Failed to allocate, replace the old function
> + * with calls to tp_stub_func.
> + */
> + for (i = 0; old[i].func; i++)

{

> + if (old[i].func == tp_func->func &&
> + old[i].data == tp_func->data) {

like here.

> + old[i].func = tp_stub_func;
> + /* Set the prio to the next event. */
> + if (old[i + 1].func)
> + old[i].prio =
> + old[i + 1].prio;

multi line demands { }, but in this case just don't line-break.

> + else
> + old[i].prio = -1;
> + }

}

> + *funcs = old;
> + }
> }
> debug_print_probes(*funcs);
> return old;
> @@ -295,10 +341,12 @@ static int tracepoint_remove_func(struct tracepoint *tp,
> tp_funcs = rcu_dereference_protected(tp->funcs,
> lockdep_is_held(&tracepoints_mutex));
> old = func_remove(&tp_funcs, func);
> - if (IS_ERR(old)) {
> - WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM);
> + if (WARN_ON_ONCE(IS_ERR(old)))
> return PTR_ERR(old);
> - }
> +
> + if (tp_funcs == old)
> + /* Failed allocating new tp_funcs, replaced func with stub */
> + return 0;

{ }