Re: [PATCH net-next] docs: net: fix outdated default values of four sysctls

[Hangbin Liu]

On Sun, Nov 08, 2026 at 06:17:46AM +0000, Gopal Malaviya wrote:
> The defaults documented in ip-sysctl.rst for four sysctls differ from
> the values the kernel actually uses:
> 
>   sysctl                  documented  actual
>   cipso_rbm_strictvalid   0           1
>   flowlabel_state_ranges  1           0
>   router_solicitations    3           -1
>   regen_max_retry         5           3
> 
> Each one went stale when the code changed and the documentation was not
> updated, or was wrong from the start:
> 
> - cipso_v4_rbm_strictvalid has been initialised to 1 since CIPSO was
>   merged, while the documentation added with it said 0.
> - Commit be26849bfb6f ("ipv6: Disable flowlabel state ranges by
>   default") changed the default of flowlabel_state_ranges to 0.
> - Commit bd11f0741fa5 ("ipv6 addrconf: implement RFC7559 router
>   solicitation backoff") changed MAX_RTR_SOLICITATIONS from 3 to -1,
>   meaning that router solicitations are sent without a limit. The
>   documentation was not updated and never mentioned -1.
> - Commit 76f793e3a471 ("ipv6: updates to privacy addresses per RFC
>   4941.") changed REGEN_MAX_RETRY from 5 to 3.
> 
> Update the four defaults and note that -1 means no limit for
> router_solicitations.
> 
> The mismatches were found with the help of an AI assistant (Claude),
> which compared the defaults documented in ip-sysctl.rst with the values
> under /proc/sys/net on a running kernel and with the initial values in
> the source. I confirmed each value with sysctl on a running kernel and
> against the net-next source and the commits below. The commit message
> was drafted with the same assistance.
> 
> Tested by building the networking documentation with
> "make SPHINXDIRS=networking htmldocs": the change adds no warnings and
> the four defaults render as updated.
> 
> Fixes: 8802f616f6de ("[NetLabel]: documentation")
> Fixes: be26849bfb6f ("ipv6: Disable flowlabel state ranges by default")
> Fixes: bd11f0741fa5 ("ipv6 addrconf: implement RFC7559 router solicitation backoff")
> Fixes: 76f793e3a471 ("ipv6: updates to privacy addresses per RFC 4941.")
> Signed-off-by: Gopal Malaviya <gopalmalaviya53@xxxxxxxxx>
> ---
>  Documentation/networking/ip-sysctl.rst | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> index bc22400b53..0b7bfbd98a 100644
> --- a/Documentation/networking/ip-sysctl.rst
> +++ b/Documentation/networking/ip-sysctl.rst
> @@ -1587,7 +1587,7 @@ cipso_rbm_strictvalid - BOOLEAN
>  	- 0 (disabled)
>  	- 1 (enabled)
>  
> -	Default: 0 (disabled)
> +	Default: 1 (enabled)
>  
>  IP Variables
>  ============
> @@ -2418,7 +2418,7 @@ flowlabel_state_ranges - BOOLEAN
>  	- 0 (disabled)
>  	- 1 (enabled)
>  
> -	Default: 1 (enabled)
> +	Default: 0 (disabled)
>  
>  
>  flowlabel_reflect - INTEGER
> @@ -2956,9 +2956,9 @@ router_solicitation_interval - INTEGER
>  
>  router_solicitations - INTEGER
>  	Number of Router Solicitations to send until assuming no
> -	routers are present.
> +	routers are present. A value of -1 means no limit.
>  
> -	Default: 3
> +	Default: -1
>  
>  use_oif_addrs_only - BOOLEAN
>  	When enabled, the candidate source addresses for destinations
> @@ -3034,7 +3034,7 @@ regen_max_retry - INTEGER
>  	Number of attempts before give up attempting to generate
>  	valid temporary addresses.
>  
> -	Default: 5
> +	Default: 3
>  
>  max_addresses - INTEGER
>  	Maximum number of autoconfigured addresses per interface.  Setting
> 
> base-commit: fa5196392691051963726787944db872420dfa75
> -- 
> 2.43.0
> 

Checked with the source and sysctl output, all works good to me.

Reviewed-by: Hangbin Liu <liuhangbin@xxxxxxxxxx>