Re: [RFC net 1/2] netdev-genl: Hold rcu_read_lock in napi_get

From: Jakub Kicinski
Date: Tue Nov 12 2024 - 20:28:56 EST


On Tue, 12 Nov 2024 18:13:58 +0000 Joe Damato wrote:
> +/* must be called under rcu_read_lock(), because napi_by_id requires it */
> +static struct napi_struct *__do_napi_by_id(unsigned int napi_id,
> + struct genl_info *info, int *err)
> +{
> + struct napi_struct *napi;
> +
> + napi = napi_by_id(napi_id);
> + if (napi) {
> + *err = 0;
> + } else {
> + NL_SET_BAD_ATTR(info->extack, info->attrs[NETDEV_A_NAPI_ID]);
> + *err = -ENOENT;
> + }
> +
> + return napi;
> +}

Thanks for the quick follow up! I vote we don't factor this out.
I don't see what it buys us, TBH, normally we factor out code
to avoid having to unlock before return, but this code doesn't
have extra returns...

Just slap an rcu_read_lock / unlock around and that's it?

Feel free to repost soon.