On Thu, Aug 22, 2024 at 12:02 AM Tze-nan Wu (吳澤南)
<Tze-nan.Wu@xxxxxxxxxxxx> wrote:
>
>
> BTW, If this should be handled in kernel, modification shown below
> could fix the issue without breaking the "static_branch" usage in both
> macros:
>
>
> +++ /include/linux/bpf-cgroup.h:
> -#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen)
> +#define BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen, compat)
> ({
> int __ret = 0;
> if (cgroup_bpf_enabled(CGROUP_GETSOCKOPT))
> copy_from_sockptr(&__ret, optlen, sizeof(int));
> + else
> + *compat = true;
> __ret;
> })
>
> #define BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock, level, optname,
> optval, optlen, max_optlen, retval)
> ({
> int __ret = retval;
> - if (cgroup_bpf_enabled(CGROUP_GETSOCKOPT) &&
> - cgroup_bpf_sock_enabled(sock, CGROUP_GETSOCKOPT))
> + if (cgroup_bpf_sock_enabled(sock, CGROUP_GETSOCKOPT))
> if (!(sock)->sk_prot->bpf_bypass_getsockopt ||
> ...
>
> +++ /net/socket.c:
> int do_sock_getsockopt(struct socket *sock, bool compat, int level,
> {
> ...
> ...
> + /* The meaning of `compat` variable could be changed here
> + * to indicate if cgroup_bpf_enabled(CGROUP_SOCK_OPS) is
> false.
> + */
> if (!compat)
> - max_optlen = BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen);
> + max_optlen = BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen,
> &compat);
This is better, but it's still quite a hack. Let's not override it.
We can have another bool, but the question:
do we really need BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN ?
copy_from_sockptr(&__ret, optlen, sizeof(int));
should be fast enough to do it unconditionally.
What are we saving here?
Stan ?
>
> > Thanks,
> > --tze-nan
>
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