Re: [PATCH v2 1/2] net: make driver settling time configurable

[David <david@xxxxxxxxxx>]

On 2/8/24 11:26, Denis Kirjanov wrote:
> On 2/8/24 12:52, David Ventura wrote:
> > During IP auto configuration, some drivers apparently need to wait a
> > certain length of time to settle; as this is not true for all drivers,
> > make this length of time configurable.
> >
> > Signed-off-by: David Ventura <david@xxxxxxxxxx>
> > ---
> >   .../admin-guide/kernel-parameters.txt         |  4 ++++
> >   Documentation/admin-guide/nfs/nfsroot.rst     |  3 +++
> >   net/ipv4/ipconfig.c                           | 23 ++++++++++++++++---
> >   3 files changed, 27 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index b47940577c10..b07a035642fa 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2291,6 +2291,10 @@
> >   
> >   	ip=		[IP_PNP]
> >   			See Documentation/admin-guide/nfs/nfsroot.rst.
> > +	ip.dev_wait_ms=
> > +			[IP_PNP]
> > +			See Documentation/admin-guide/nfs/nfsroot.rst.
> > +
> >   
> >   	ipcmni_extend	[KNL,EARLY] Extend the maximum number of unique System V
> >   			IPC identifiers from 32,768 to 16,777,216.
> > diff --git a/Documentation/admin-guide/nfs/nfsroot.rst b/Documentation/admin-guide/nfs/nfsroot.rst
> > index 135218f33394..f26f7a342af6 100644
> > --- a/Documentation/admin-guide/nfs/nfsroot.rst
> > +++ b/Documentation/admin-guide/nfs/nfsroot.rst
> > @@ -223,6 +223,9 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:<dns
> >     /proc/net/ipconfig/ntp_servers to an NTP client before mounting the real
> >     root filesystem if it is on NFS).
> >   
> > +ip.dev_wait_ms=<value>
> > +  Set the number of milliseconds to delay after opening the network device
> > +  which will be autoconfigured. Defaults to 10 milliseconds.
> >   
> >   nfsrootdebug
> >     This parameter enables debugging messages to appear in the kernel
> > diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
> > index c56b6fe6f0d7..cbf35163b973 100644
> > --- a/net/ipv4/ipconfig.c
> > +++ b/net/ipv4/ipconfig.c
> > @@ -82,8 +82,6 @@
> >   #define IPCONFIG_DYNAMIC
> >   #endif
> >   
> > -/* Define the friendly delay before and after opening net devices */
> > -#define CONF_POST_OPEN		10	/* After opening: 10 msecs */
> >   
> >   /* Define the timeout for waiting for a DHCP/BOOTP/RARP reply */
> >   #define CONF_OPEN_RETRIES 	2	/* (Re)open devices twice */
> > @@ -101,6 +99,7 @@
> >   
> >   /* Wait for carrier timeout default in seconds */
> >   static unsigned int carrier_timeout = 120;
> > +static unsigned int dev_wait_ms = 10;
> >   
> >   /*
> >    * Public IP configuration
> > @@ -1516,7 +1515,8 @@ static int __init ip_auto_config(void)
> >   		return err;
> >   
> >   	/* Give drivers a chance to settle */
> > -	msleep(CONF_POST_OPEN);
> > +	if(dev_wait_ms > 0)
> > +		msleep(dev_wait_ms);
> What's the point to wait more than CONF_POST_OPEN with the change?

I didn't have anything specificin mind - shall I change this

to only enable/disable the 10ms wait instead of allowing a configurable 
value?

> >   
> >   	/*
> >   	 * If the config information is insufficient (e.g., our IP address or
> > @@ -1849,3 +1849,20 @@ static int __init set_carrier_timeout(char *str)
> >   	return 1;
> >   }
> >   __setup("carrier_timeout=", set_carrier_timeout);
> > +
> > +
> > +static int __init set_dev_wait_ms(char *str)
> > +{
> > +	ssize_t ret;
> > +
> > +	if (!str)
> > +		return 0;
> > +
> > +	ret = kstrtouint(str, 0, &dev_wait_ms);
> > +	if (ret)
> > +		return 0;
> > +
> > +	return 1;
> > +}
> > +
> > +__setup("ip.dev_wait_ms=", set_dev_wait_ms);