Re: [PATCH 1/3 net-next v3] ipv4: centralize devconf sysctl handling

[Nicolas Dichtel <nicolas.dichtel@6wind.com>]

Le 04/05/2026 à 14:31, Fernando Fernandez Mancera a écrit :
> The logic for handling IPv4 devconf sysctls is scattered. Notification
> and cache flushes are managed in devinet_conf_proc(), while a separate
> ipv4_doint_and_flush() function and DEVINET_SYSCTL_FLUSHING_ENTRY macro
> is used for properties that solely require a cache flush.
> 
> This patch refactors the sysctl handling by introducing a centralized
> helper, devinet_conf_post_set(). This new function evaluates the changed
> attribute and handles all necessary operations like triggering netlink
> notifications. It returns a boolean indicating whether a routing cache
> flush is required.
> 
> Note that the boolean is necessary as this function will be re-used for
> netlink IPv4 devconf handling where the cache flushing must wait until
> all the attributes have been processed.
> 
> Finally, this is introducing a small change in behavior for
> IPV4_DEVCONF_ROUTE_LOCALNET. As commit d0daebc3d622 ("ipv4: Add
> interface option to enable routing of 127.0.0.0/8") intended, the cache
> flush should only be performed when ROUTE_LOCALNET changes from 1 to 0.
> Unfortunately, this was not true because while implementing it the
> DEVINET_SYSCTL_FLUSHING_ENTRY was used for the attribute, making the
> code related to it on devinet_conf_proc() dead.
> 
> IPV4_DEVCONF_FORWARDING is still being handled separately as it requires
> more operations.
> 
> Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>

Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>