> > Can you find a hole further down to place this in, or at least a spot
> > that does not result in 7b of wasted space (in the hotpath cacheline
> > groups of all places).
>
> There is one place where I can simply insert the flag.
>
> The diff patch on top of this series is:
> diff --git a/include/net/sock.h b/include/net/sock.h
> index e85d6fb3a2ba..9fa27693fb02 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -446,8 +446,6 @@ struct sock {
> u32 sk_reserved_mem;
> int sk_forward_alloc;
> u32 sk_tsflags;
> -#define SK_BPF_CB_FLAG_TEST(SK, FLAG) ((SK)->sk_bpf_cb_flags & (FLAG))
> - u8 sk_bpf_cb_flags;
> __cacheline_group_end(sock_write_rxtx);
>
> __cacheline_group_begin(sock_write_tx);
> @@ -528,6 +526,8 @@ struct sock {
> u8 sk_txtime_deadline_mode : 1,
> sk_txtime_report_errors : 1,
> sk_txtime_unused : 6;
> +#define SK_BPF_CB_FLAG_TEST(SK, FLAG) ((SK)->sk_bpf_cb_flags & (FLAG))
> + u8 sk_bpf_cb_flags;
>
> void *sk_user_data;
> #ifdef CONFIG_SECURITY
>
>
> 1) before applying the whole series:
> ...
> /* --- cacheline 10 boundary (640 bytes) --- */
> ktime_t sk_stamp; /* 0x280 0x8 */
> int sk_disconnects; /* 0x288 0x4 */
> u8 sk_txrehash; /* 0x28c 0x1 */
> u8 sk_clockid; /* 0x28d 0x1 */
> u8 sk_txtime_deadline_mode:1; /* 0x28e: 0 0x1 */
> u8 sk_txtime_report_errors:1; /*
> 0x28e:0x1 0x1 */
> u8 sk_txtime_unused:6; /* 0x28e:0x2 0x1 */
>
> /* XXX 1 byte hole, try to pack */
>
> void * sk_user_data; /* 0x290 0x8 */
> void * sk_security; /* 0x298 0x8 */
> struct sock_cgroup_data sk_cgrp_data; /* 0x2a0 0x10 */
> ...
> /* sum members: 773, holes: 1, sum holes: 1 */
>
>
> 2) after applying the series with the above diff patch:
> ...
> /* --- cacheline 10 boundary (640 bytes) --- */
> ktime_t sk_stamp; /* 0x280 0x8 */
> int sk_disconnects; /* 0x288 0x4 */
> u8 sk_txrehash; /* 0x28c 0x1 */
> u8 sk_clockid; /* 0x28d 0x1 */
> u8 sk_txtime_deadline_mode:1; /* 0x28e: 0 0x1 */
> u8 sk_txtime_report_errors:1; /*
> 0x28e:0x1 0x1 */
> u8 sk_txtime_unused:6; /* 0x28e:0x2 0x1 */
> u8 sk_bpf_cb_flags; /* 0x28f 0x1 */
> void * sk_user_data; /* 0x290
> 0x8 */
> void * sk_security; /* 0x298 0x8 */
> struct sock_cgroup_data sk_cgrp_data; /* 0x2a0 0x10 */
> ...
> /* sum members: 774 */
>
> It turns out that the new sk_bpf_cb_flags fills the hole exactly. The
> new field and some of its nearby fields are quite similar because they
> are only/nearly written during the creation or setsockopt phase.
>
> I think now it's a good place to insert the new flag?
Thanks. This seems fine to me.
