Re: [RFC] net: picoping: try to make it asynchronious: fail

[Sascha Hauer <s.hauer@pengutronix.de>]

On Fri, May 30, 2014 at 01:14:08PM +0400, Antony Pavlov wrote:
> Picotcp tends to work in an asynchronious way.
> 
> E.g. for ping we have to use "pico_icmp4_ping()"
> (to start ping task) and the special icmp4 handler
> (callback function) "cb_ping()".
> 
> But the ping command in barebox works in very simple
> way:
> 
>   * user types 'ping <IP>' in the barebox shell command line;
>   * the ping command takes all control until it gets the positive
>     or a negative result;
>   * the control is returned to the barebox shell.
> 
> To use asynchronious-oriented picotcp functions in syncronious-oriented
> barebox workflow we have to work out necessary picotcp usage template.
> 
> This patch propose simplest template. But this template has two major
> disadvantages:
> 
>   * user can't completely cancel ping using ctrl-c,
>     the ping request send task continue to work in the background:
> 
>     barebox@barebox sandbox:/ picoping 10.0.0.2
>     48 bytes from 10.0.0.2: icmp_req=1 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=2 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=3 ttl=64 time=0 ms
>     <ctrl-c> pressed
>     barebox@barebox sandbox:/ picoping 10.0.0.2
>     48 bytes from 10.0.0.2: icmp_req=1 ttl=64 time=1 ms
>     48 bytes from 10.0.0.2: icmp_req=5 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=2 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=6 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=3 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=7 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=4 ttl=64 time=0 ms
>     48 bytes from 10.0.0.2: icmp_req=8 ttl=64 time=0 ms
> 
>   * user has to press <ctrl-c> after the last ping response is received
>     to return to barebox shell.
> 
> Has anybody any ideas how to improve the situation?

This must be solved in the pico_icmp4.c code. The counterpart of
pico_tree_insert (pico_tree_delete?) must be called as an response to
ctrlc().

How I see it pico_icmp4_ping should return the cookie so that a ping
abort function can be implemented:

void pico_icmp4_ping_abort(struct pico_icmp4_ping_cookie *cookie)
{
	pico_tree_delete(cookie);

	release_whatever_resources();
}

Sascha

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