Re: __VA_ARGS__izing IEEE80211_DPRINTF[2]()

From: Brian F. Feldman (green_at_freebsd.org)
Date: 11/05/03

  • Next message: Brian Fundakowski Feldman: "my 802.11 work" 
    To: Sam Leffler <sam@errno.com>
Date: Wed, 05 Nov 2003 17:17:17 -0500

    Sam Leffler <sam@errno.com> wrote:
    > On Wednesday 05 November 2003 10:04 am, Brian Fundakowski Feldman wrote:
    > > Would it be a problem to make the following change to src/sys/net80211 so
    > > that the debug messages aren't totally useless for systems that have more
    > > than one card (or confusing on systems that just have one)? Obviously, it
    > > would also involve removing the extra parentheses in each of the callers as
    > > well.
    > >
    > > Old:
    > > #define IEEE80211_DPRINTF(X) if (ieee80211_debug) printf X
    > > #define IEEE80211_DPRINTF2(X) if (ieee80211_debug>1) printf X
    > >
    > > New:
    > > #define IEEE80211_DPRINTF(...) do { \
    > > if (ieee80211_debug) \
    > > if_printf(&ic->ic_ifp, __VA_ARGS__); \
    > > while (0)
    > >
    > > The only place this wouldn't work is ieee80211_decap(), so I'd change it to
    > > add a local "ic" variable when compiled for debugging. There's an easy
    > > fallback for non-C99 compilers, too; it just wouldn't print the interface:
    > >
    > > static __inline void
    > > IEEE80211_DPRINTF(const char *fmt, ...)
    > > {
    > >
    > > if (ieee80211_debug) {
    > > va_list ap;
    > >
    > > va_start(ap, fmt);
    > > (void)vprintf(fmt, ap);
    > > va_end(ap);
    > > }
    > > }
    >
    > I can't see what your intent is from the above. If the point is to use
    > if_printf everywhere so all the printfs have a device prepended to the
    > message then I'm fine with that. However I think it's a bad idea to depend
    > on local variables existing. If you're going to do it, then add an explicit
    > argument to the macros.
    >
    > If you're trying to deal with debugging systems w/ multiple 802.11 cards then
    > you probably want debugging enabled on a per-if basis which this doesn't
    > address.
    >
    > Regardless, in all this remember that this code is shared with other systems
    > so changes like this shouldn't be done lightly.

    My intent is for the use of if_printf to prepend the interface name, yes.
    Per-interface debug flags will be trivial if we convert calls to say
    DPRINTF(ic, "fmt",...). Not using the "magic" ic is fine with me -- just
    seems a shame because it's pervasive in just about every function you'd ever
    want to DPRINTF() from. 

    -- 
Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
  <> green@FreeBSD.org                               \  The Power to Serve! \
 Opinions expressed are my own.                       \,,,,,,,,,,,,,,,,,,,,,,\
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