On Sun, 10 Jul 2022 23:11:43 +0800
Tao Zhou <tao.zhou@xxxxxxxxx> wrote:
> The @*pos of enable_monitors_start() can not be -1 or other negative value.
> And I checked that the *pos is 0(right?). That is safe. Sorry for not being
> that ture and maybe this is a notice here. Because if it is a negative value,
> the returned m_def is a point to a data place 16 bytes before &rv_monitors_list.
> That is a not ture rv_monitors_list stucture data. But it is not possiable now.
> Maybe "inspired" from your question. Look it more, I image this simulation.
> If the monitor(and all is enabled) is more enough to let the *pos to increase
> to -1. And the returned m_def is last monitor that returned from enable_monitors_start().
> The enable_monitors_next() check from the last monitor and return NULL.
> Only show the last monitor. This will not really happen I think.
> But I am not focus enough to the seq file code or others now, so this may be
> more possible to be not right. Late reply continued from me..
So basically you are saying we should have:
> +static void *enabled_monitors_start(struct seq_file *m, loff_t *pos)
> +{
> + struct rv_monitor_def *m_def;
> + loff_t l;
> +
> + mutex_lock(&rv_interface_lock);
if (list_empty(&rv_monitors_list->list))
return NULL;
?
Probably safer to have that.
-- Steve
> + m_def = list_entry(&rv_monitors_list, struct rv_monitor_def, list);
> +
> + for (l = 0; l <= *pos; ) {
> + m_def = enabled_monitors_next(m, m_def, &l);
> + if (!m_def)
> + break;
> + }
> +
> + return m_def;
> +}
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