Re: [PATCH v2 1/7] fault-inject: add support for static keys around fault injection sites

[Steven Rostedt]

On Thu, 20 Jun 2024 00:48:55 +0200
Vlastimil Babka <vba...@suse.cz> wrote:

> +static int debugfs_prob_set(void *data, u64 val)
> +{
> +     struct fault_attr *attr = data;
> +
> +     mutex_lock(&probability_mutex);
> +
> +     if (attr->active) {
> +             if (attr->probability != 0 && val == 0) {
> +                     static_key_slow_dec(attr->active);
> +             } else if (attr->probability == 0 && val != 0) {
> +                     static_key_slow_inc(attr->active);
> +             }
> +     }

So basically the above is testing if val to probability is going from
zero or non-zero. For such cases, I find it less confusing to have:

        if (attr->active) {
                if (!!attr->probability != !!val) {
                        if (val)
                                static_key_slow_inc(attr->active);
                        else
                                static_key_slow_dec(attr->active);
                }
        }

This does add a layer of nested ifs, but IMO it's a bit more clear in
what is happening, and it gets rid of the "else if".

Not saying you need to change it. This is more of an FYI.

-- Steve


> +
> +     attr->probability = val;
> +
> +     mutex_unlock(&probability_mutex);
> +
> +     return 0;
> +}