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

[Peter Zijlstra]

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;

{ }