[PATCH] net: on ifup -a only detect devices when necessary

[Michael Tretter]

On Fri, 06 Apr 2018 15:16:39 +0200, Sascha Hauer wrote:
> For network boot we once used to hardcode eth0, but in latest changes
> this was changed to work with different network devices and the 'ifup
> eth0' was replaced with 'ifup -a' which lead to the result that we now
> detect all devices in order to eventually also bring up USB network
> adapters. In most of the cases this is not desired. When a board has
> internal network support this is likely to be used. With this patch
> we only detect all devices when we do not have a network device already.
> For the unusual case in which a USB network adapter shall be used
> even when an internal network interface is present we introduce the
> global variable "global.net.ifup_force_detect" which can be used to
> force detection of devices.
> 
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>

Tested-by: Michael Tretter <m.tretter at pengutronix.de>

Michael

> ---
>  net/ifup.c | 21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ifup.c b/net/ifup.c
> index 827c5c03d1..d550f82530 100644
> --- a/net/ifup.c
> +++ b/net/ifup.c
> @@ -28,6 +28,9 @@
>  #include <globalvar.h>
>  #include <string.h>
>  #include <driver.h>
> +#include <init.h>
> +#include <globalvar.h>
> +#include <magicvar.h>
>  #include <linux/stat.h>
>  
>  static int eth_discover(char *file)
> @@ -245,6 +248,8 @@ int ifup(const char *ethname, unsigned flags)
>  	return ifup_edev(edev, flags);
>  }
>  
> +static int net_ifup_force_detect;
> +
>  int ifup_all(unsigned flags)
>  {
>  	struct eth_device *edev;
> @@ -266,7 +271,9 @@ int ifup_all(unsigned flags)
>  
>  	closedir(dir);
>  
> -	device_detect_all();
> +	if ((flags & IFUP_FLAG_FORCE) || net_ifup_force_detect ||
> +	    list_empty(&netdev_list))
> +		device_detect_all();
>  
>  	for_each_netdev(edev)
>  		ifup_edev(edev, flags);
> @@ -274,6 +281,18 @@ int ifup_all(unsigned flags)
>  	return 0;
>  }
>  
> +static int ifup_all_init(void)
> +{
> +	globalvar_add_simple_bool("net.ifup_force_detect", &net_ifup_force_detect);
> +
> +	return 0;
> +}
> +late_initcall(ifup_all_init);
> +
> +BAREBOX_MAGICVAR_NAMED(global_net_ifup_force_detect,
> +                       global.net.ifup_force_detect,
> +                       "net: force detection of devices on ifup -a");
> +
>  #if IS_ENABLED(CONFIG_NET_CMD_IFUP)
>  
>  static int do_ifup(int argc, char *argv[])