[cip-dev] [PATCH 4.4.y V2] net: ipconfig: Support using "delayed" DHCP replies

Pavel Machek pavel at denx.de
Thu May 2 21:19:29 UTC 2019


> The dhcp code only waits 1s between sending DHCP requests on different
> devices and only accepts an answer for the device that sent out the last
> request. Only the timeout at the end of a loop is increased iteratively
> which favours only the last device. This makes it impossible to work
> with a dhcp server that takes little more than 1s connected to a device
> that is not the last one.
> Instead of also increasing the inter-device timeout, teach the code to
> handle delayed replies.
> To accomplish that, make *ic_dev track the current ic_device instead of
> the current net_device and adapt all users accordingly. The relevant
> change then is to reset d to ic_dev on a reply to assert that the
> followup request goes through the right device.


In the end I decided to apply this one. It is true that the alternate
fix is one-liner, but I would not be sure if other timing parameters
need changing, and would not have a good way to test that.

Best regards,

> --- a/net/ipv4/ipconfig.c
> +++ b/net/ipv4/ipconfig.c
> @@ -94,7 +94,6 @@
>  /* Define the timeout for waiting for a DHCP/BOOTP/RARP reply */
>  #define CONF_OPEN_RETRIES 	2	/* (Re)open devices twice */
>  #define CONF_SEND_RETRIES 	6	/* Send six requests per open */
> -#define CONF_INTER_TIMEOUT	(HZ)	/* Inter-device timeout: 1 second */
>  #define CONF_BASE_TIMEOUT	(HZ*2)	/* Initial timeout: 2 seconds */
>  #define CONF_TIMEOUT_RANDOM	(HZ)	/* Maximum amount of randomization */
>  #define CONF_TIMEOUT_MULT	*7/4	/* Rate of timeout growth */

(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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