[QUERY] signal_struct->count/live

[Oleg Nesterov]

On 11/27, Ananth N Mavinakayanahalli wrote:
>
> I am confused as to why we need two atomics count and live in signal_struct.
>
> report_death() uses ->live as the group_dead indicator,

report_death? Perhaps you meant do_exit() ?

> while there are
> places (like the scheduler) which uses ->count as the nr_threads
> indicator.
>
> I tried git blame to see if it remembers why, but the addition predates
> 2.6.12 and so it does not know.
>
> Could you please shed some light on this?

In short: signal->count must die. I was going to do this a long ago
but never had the time. See also 4ab6c08336535f8c8e42cf45d7adeda882eff06e
commit, this is the first step.

Last time I did the grepping almost any usage of signal->count is
not right. For example, __exit_signal() is correct, but it doesn't
need to use ->count.

Except: it is needed for things like get_nr_threads() in proc.

In short: never use signal->count ;)

Oleg.