[RFC][PATCH v2 19/31] timers: net: Use del_timer_shutdown() before freeing timer

[Steven Rostedt]

Could someone from networking confirm (or deny) that the timer being
removed in sk_stop_timer() will no longer be used even if del_timer()
returns false?

net/core/sock.c:

void sk_stop_timer(struct sock *sk, struct timer_list* timer)
{
	if (del_timer(timer))
		__sock_put(sk);
}

If this is the case, then I'll add the following interface:

   del_timer_sync_shutdown() // the common case which syncs

   del_timer_shutdown() // the uncommon case, that returns immediately
                        // used for those cases that add extra code to
                        // handle it, like sk_stop_timer()


Which has the same semantics as del_timer_sync() and del_timer()
respectively, but will prevent the timer from being rearmed again.

This way we can convert the sk_stop_timer() to:

void sk_stop_timer(struct sock *sk, struct timer_list* timer)
{
	if (del_timer_shutdown(timer))
		__sock_put(sk);
}


We can also add the del_timer_shutdown() to other locations that need to
put a timer into a shutdown state before freeing, and where it's in a
context that can not call del_timer_sync_shutdown().

-- Steve