[PATCH v2 0/2] net: ipconfig: remove wait for drivers

[PATCH v2 0/2] net: ipconfig: remove wait for drivers

[David Ventura]

Currently ip autoconfiguration has a hardcoded delay of 10ms.

Make the delay configurable via the new `ip.dev_wait_ms` argument, and
set the default value to 0ms.
    

    David

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

[David Ventura]

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@davidv.dev>
---
 .../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);
 
 	/*
 	 * 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);
-- 
2.39.2

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

[Denis Kirjanov]

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@davidv.dev>
> ---
>  .../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?

>  
>  	/*
>  	 * 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);

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

[David]

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@davidv.dev>
>> ---
>>   .../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);

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

[Jakub Kicinski]

On Thu,  8 Feb 2024 10:52:29 +0100 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.

Please CC folks who gave you feedback, Andrew's is missing.

Andrew, what do you think about just removing the wait?
Or decreasing it to 1ms?
It feels a little wasteful to be adding uAPI for something
which as you said is likely papering over ancient bugs. We'll 
fix the bugs which are still around and the uAPI will stay 
forever :(

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

[Andrew Lunn]

On Fri, Feb 09, 2024 at 01:59:44PM -0800, Jakub Kicinski wrote:
> On Thu,  8 Feb 2024 10:52:29 +0100 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.
> 
> Please CC folks who gave you feedback, Andrew's is missing.
> 
> Andrew, what do you think about just removing the wait?
> Or decreasing it to 1ms?
> It feels a little wasteful to be adding uAPI for something
> which as you said is likely papering over ancient bugs. We'll 
> fix the bugs which are still around and the uAPI will stay 
> forever :(

My guess is, the broken drivers are doing setup stuff after they call
netdev_register().

Reducing it to 1ms will probably continue to hide such bugs. So we
could just go with that, and probably not see any regressions. Or we
can decide we really do want to know about broken drivers, and just
remove the delay.

Either way, we don't need a new uAPI.

David, is 1ms too long for you? If we do take the delay out, you are
going to receive some of the flack from regression reports.

      Andrew

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

[David]

On 2/9/24 23:11, Andrew Lunn wrote:
> On Fri, Feb 09, 2024 at 01:59:44PM -0800, Jakub Kicinski wrote:
>> On Thu,  8 Feb 2024 10:52:29 +0100 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.
>> Please CC folks who gave you feedback, Andrew's is missing.
Thanks for the feedback, still learning this workflow
>>
>> Andrew, what do you think about just removing the wait?
>> Or decreasing it to 1ms?
>> It feels a little wasteful to be adding uAPI for something
>> which as you said is likely papering over ancient bugs. We'll
>> fix the bugs which are still around and the uAPI will stay
>> forever :(
> My guess is, the broken drivers are doing setup stuff after they call
> netdev_register().
>
> Reducing it to 1ms will probably continue to hide such bugs. So we
> could just go with that, and probably not see any regressions. Or we
> can decide we really do want to know about broken drivers, and just
> remove the delay.
>
> Either way, we don't need a new uAPI.

Would it make sense to move this to a build-time configuration flag?

I do not have a gut-feeling for which behaviors should be configurable

at build vs run time.

> David, is 1ms too long for you? If we do take the delay out, you are
> going to receive some of the flack from regression reports.

I've used this patch to experiment with different values, and the sleep time

behaves as described in Documentation/timers/timers-howto.rst, that is, a

call of `msleep(1)` usually delays boot time by 12~13 ms in my tests.

On top of this, I'm running this specific example on a no-smp systemm, 
where I

do not believe the `msleep` achieves anything (but I'm a kernel newbie 
so please

correct me if I'm wrong).

>
>        Andrew
>

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

[Andrew Lunn]

> Would it make sense to move this to a build-time configuration flag?
> 
> I do not have a gut-feeling for which behaviors should be configurable
> 
> at build vs run time.

If it is build time, it becomes the distribution problem to pick a
value.

Might be best to just bite the bullet, set it to 0, and fixup whatever
breaks.

	Andrew

[PATCH v2 2/2] net: Change default delay on IP autoconfig to 0ms

[David Ventura]

Reduce the default settle time from 10ms to 0ms, based on previous discussions (
https://lore.kernel.org/netdev/1305696161-18277-1-git-send-email-micha@neli.hopto.org/t/
https://lore.kernel.org/netdev/580001e3-17ef-4f24-8fd8-bc14110e874e@lunn.ch/
) ARP and DHCP retries are expected to handle any lost transmissions.

This patch depends on 1f0aa0c947eeb4edb60add141a5bc2309f2dc8dd ("
net: make driver settling time configurable").

Signed-off-by: David Ventura <david@davidv.dev>
---
 Documentation/admin-guide/nfs/nfsroot.rst | 2 +-
 net/ipv4/ipconfig.c                       | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/nfs/nfsroot.rst b/Documentation/admin-guide/nfs/nfsroot.rst
index f26f7a342af6..fce610a4ec54 100644
--- a/Documentation/admin-guide/nfs/nfsroot.rst
+++ b/Documentation/admin-guide/nfs/nfsroot.rst
@@ -225,7 +225,7 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:<dns
 
 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.
+  which will be autoconfigured. Defaults to 0 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 cbf35163b973..8b7d08649b09 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -99,7 +99,7 @@
 
 /* Wait for carrier timeout default in seconds */
 static unsigned int carrier_timeout = 120;
-static unsigned int dev_wait_ms = 10;
+static unsigned int dev_wait_ms = 0;
 
 /*
  * Public IP configuration
-- 
2.39.2

Re: [PATCH v2 0/2] net: ipconfig: remove wait for drivers

[Denis Kirjanov]

On 2/8/24 12:35, David Ventura wrote:
> Currently ip autoconfiguration has a hardcoded delay of 10ms.

The subject line should be prefixed with net-next

> 
> Make the delay configurable via the new `ip.dev_wait_ms` argument, and
> set the default value to 0ms.
>     
> 
>     David
> 
> 
> 

Re: [PATCH v2 0/2] net: ipconfig: remove wait for drivers

[Jakub Kicinski]

On Thu,  8 Feb 2024 10:35:53 +0100 David Ventura wrote:
> Currently ip autoconfiguration has a hardcoded delay of 10ms.
> 
> Make the delay configurable via the new `ip.dev_wait_ms` argument, and
> set the default value to 0ms.

Does not apply, you'll have to respin:

Applying: net: make driver settling time configurable
error: sha1 information is lacking or useless (Documentation/admin-guide/kernel-parameters.txt).
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 net: make driver settling time configurable
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".