linux-kernel - Re: [External] Re: [PATCH v2] sock: add tracepoint for send recv length

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Date:   Fri, 6 Jan 2023 12:23:41 +0800
From:   运辉崔 <cuiyunhui@...edance.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     mhiramat@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, duanxiongchun@...edance.com,
        kuniyu@...zon.com, linux-kernel@...r.kernel.org,
        linux-trace-kernel@...r.kernel.org
Subject: Re: [External] Re: [PATCH v2] sock: add tracepoint for send recv length

On Fri, Jan 6, 2023 at 12:07 PM Steven Rostedt <rostedt@...dmis.org> wrote:
>
> On Fri, 6 Jan 2023 11:24:18 +0800
> 运辉崔 <cuiyunhui@...edance.com> wrote:
>
> > Regardless of whether the MSG_PEEK flag is set or not, it is possible
> > to return -errno,
> > but based on your suggestion, I plan to modify it like this:
> >
> > trace_sock_recvmsg_length(sock->sk, sock->sk->sk_family,
> >                           sock->sk->sk_protocol,
> >                           !(flags & MSG_PEEK) ? ret : (ret < 0 ? ret : 0),
> >
> > what do you think?
>
> Sure.

Ok, Thank you.

>
> But note, from your original patch:
>
> > +     trace_sock_recvmsg_length(sock->sk, sock->sk->sk_family,
> > +                               sock->sk->sk_protocol,
> > +                               (ret > 0 && !(flags & MSG_PEEK)) ?
> > +                               ret : 0,
> > +                               (ret > 0 && !(flags & MSG_PEEK)) ? 0 : ret,
> > +                               flags);
>
> If flags MSG_PEEK is set, you return ret in error regardless, so error
> would be ret even if it was positive.
>
> So I'm guessing that this change actually fixed a bug. ;-)
>
> -- Steve

Ha-ha, seems like it，I will modify these and post v3.

Thanks,
Yunhui