Re: [PATCH v2 6/8] socket: Add SO_TIMESTAMP[NS]_NEW

[Deepa Dinamani]

> > diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
> > index 00e45c80e574..352e3dc0b3d9 100644
> > --- a/arch/alpha/include/uapi/asm/socket.h
> > +++ b/arch/alpha/include/uapi/asm/socket.h
> > @@ -3,6 +3,7 @@
> >  #define _UAPI_ASM_SOCKET_H
> >
> >  #include <asm/sockios.h>
> > +#include <asm/bitsperlong.h>
> >
> >  /* For setsockopt(2) */
> >  /*
> > @@ -110,12 +111,22 @@
> >
> >  #define SO_TIMESTAMP_OLD         29
> >  #define SO_TIMESTAMPNS_OLD       35
> > +
> >  #define SO_TIMESTAMPING_OLD      37
> >
> > +#define SO_TIMESTAMP_NEW         62
> > +#define SO_TIMESTAMPNS_NEW       63
> > +
> >  #if !defined(__KERNEL__)
> >
> > -#define SO_TIMESTAMP           SO_TIMESTAMP_OLD
> > -#define SO_TIMESTAMPNS         SO_TIMESTAMPNS_OLD
> > +#if __BITS_PER_LONG == 64
> > +#define SO_TIMESTAMP           SO_TIMESTAMP_OLD
> > +#define SO_TIMESTAMPNS         SO_TIMESTAMPNS_OLD
> > +#else
> > +#define SO_TIMESTAMP (sizeof(time_t) == sizeof(__kernel_long_t) ? SO_TIMESTAMP_OLD : SO_TIMESTAMP_NEW)
> > +#define SO_TIMESTAMPNS (sizeof(time_t) == sizeof(__kernel_long_t) ? SO_TIMESTAMPNS_OLD : SO_TIMESTAMPNS_NEW)
> > +#endif
> > +
>
> This is not platform specific. Perhaps it can be deduplicated. The
> interface expects callers to include <linux/socket.h>, not
> <asm/socket.h> directly. So perhaps it can go there?

I'm not following what you are saying here.

Are you talking about in kernel users or userspace interface?

Userspace should always include sys/socket.h according to the man page.
I'm not sure if userspace can even include linux/socket.h directly.
On my distribution this includes bits/socket.h which in turn includes
asm/socket.h.

Which file gets installed as asm/socket.h is defined per architecture
in the kbuild file such as
arch/ia64/include/uapi/asm/Kbuild (without series applied):

 generic-y += poll.h
 generic-y += sembuf.h
 generic-y += shmbuf.h
 generic-y += socket.h

Also the new timestamp numbers being added are not the same for all
architectures.

So I'm not sure how this can be moved to linux/socket.h.

> This did not address yet the previous comments on consistency and
> unnecessary code churn.
>
> The existing logic to differentiate SO_TIMESTAMP from SO_TIMESTAMPNS
> in both tcp_recv_timestamp and __sock_recv_timestamp is
>
>   if (sock_flag(sk, SOCK_RCVTSTAMP)) {
>       if (sock_flag(sk, SOCK_RCVTSTAMPNS))
>           /* timespec case */
>       else
>           /* timeval case */
>   }
>
> A new level of nesting needs to be added to differentiate .._OLD from .._NEW.
>
> Even if massively changing the original functions, please do so
> consistently, either
>
>   if (sock_flag(sk, SOCK_RCVTSTAMP)) {
>       if (sock_flag(sk, SOCK_TSTAMP_NEW) {
>           /* new code */
>       } else {
>           if (sock_flag(sk, SOCK_RCVTSTAMPNS))
>               /* timespec case */
>           else
>               /* timeval case */
>      }
>   }
>
> or
>
>   if (sock_flag(sk, SOCK_RCVTSTAMP)) {
>       if (sock_flag(sk, SOCK_TSTAMP_NEW) {
>           if (sock_flag(sk, SOCK_RCVTSTAMPNS))
>               /* new timespec case */
>           else
>               /* timespec case */
>       } else {
>            if (sock_flag(sk, SOCK_RCVTSTAMPNS))
>                /* new timespec case */
>            else
>                /* timespec case */
>       }
>   }
>
> But not one variant in one function and one in the other.
>
> Deep nesting is hard to follow and, once again, massive code changes
> (even indentations) make git blame harder to use. So where possible,
> try to avoid both and just insert a branch to a new function for the
> .._NEW cases instead:
>
>   if (sock_flag(sk, SOCK_RCVTSTAMP)) {
> +      if (sock_flag(sk, SOCK_TSTAMP_NEW)
> +          __sock_recv_timestamp_new(..);
> -      if (sock_flag(sk, SOCK_RCVTSTAMPNS))
> +      else if (sock_flag(sk, SOCK_RCVTSTAMPNS))
>           /* timespec case */
>       else
>           /* timeval case */
>   }
>
> and leave the rest of the function unmodified.

Ok, I will keep the functions consistent.

-Deepa