On Thu, Nov 12, 2020 at 12:41 PM Björn Töpel <bjorn.topel@xxxxxxxxx> wrote:
>
> From: Björn Töpel <bjorn.topel@xxxxxxxxx>
>
> This option lets a user set a per socket NAPI budget for
> busy-polling. If the options is not set, it will use the default of 8.
>
> Signed-off-by: Björn Töpel <bjorn.topel@xxxxxxxxx>
> ---
>
...
> #else /* CONFIG_NET_RX_BUSY_POLL */
> static inline unsigned long net_busy_loop_on(void)
> @@ -106,7 +108,8 @@ static inline void sk_busy_loop(struct sock *sk, int nonblock)
>
> if (napi_id >= MIN_NAPI_ID)
> napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
> - READ_ONCE(sk->sk_prefer_busy_poll));
> + READ_ONCE(sk->sk_prefer_busy_poll),
> + sk->sk_busy_poll_budget ?: BUSY_POLL_BUDGET);
Please use :
READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET
Because sk_busy_loop() is usually called without socket lock being held.
This will prevent yet another KCSAN report.
> #endif
> }
>
...
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -1165,6 +1165,16 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
> else
> sk->sk_prefer_busy_poll = valbool;
> break;
> + case SO_BUSY_POLL_BUDGET:
> + if (val > sk->sk_busy_poll_budget && !capable(CAP_NET_ADMIN)) {
> + ret = -EPERM;
> + } else {
> + if (val < 0)
if (val < 0 || val > (u16)~0)
> + ret = -EINVAL;
> + else
> + sk->sk_busy_poll_budget = val;
WRITE_ONCE(sk->sk_busy_poll_budget, val);
> + }
> + break;
> #endif
>
> case SO_MAX_PACING_RATE:
> --
> 2.27.0
>
