[17/17] batman-adv: Avoid precedence issues in macros

From: Sven Eckelmann <sven@narfation.org>

It must be avoided that arguments to a macro are evaluated ungrouped (which
enforces normal operator precendence). Otherwise the result of the macro
is not well defined.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/log.h    | 12 ++++++------
 net/batman-adv/main.h   |  4 ++--
 net/batman-adv/packet.h |  2 +-
 3 files changed, 9 insertions(+), 9 deletions(-)

On Thu, 2016-10-27 at 21:01 +0200, Simon Wunderlich wrote:
> From: Sven Eckelmann <sven@narfation.org>
> 
> It must be avoided that arguments to a macro are evaluated ungrouped (which
> enforces normal operator precendence). Otherwise the result of the macro
> is not well defined.

Curiosity:

in net/batman-adv/tp_meter.c

static int batadv_tp_send(void *arg)
{
	struct batadv_tp_vars *tp_vars = arg;
	struct batadv_priv *bat_priv = tp_vars->bat_priv;
	struct batadv_hard_iface *primary_if = NULL;
	struct batadv_orig_node *orig_node = NULL;
	size_t payload_len, packet_len;
	int err = 0;

	if (unlikely(tp_vars->role != BATADV_TP_SENDER)) {
		err = BATADV_TP_REASON_DST_UNREACHABLE;
		tp_vars->reason = err;
		goto out;
	}

	orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end);
	if (unlikely(!orig_node)) {
		err = BATADV_TP_REASON_DST_UNREACHABLE;
		tp_vars->reason = err;
		goto out;
	}

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (unlikely(!primary_if)) {
		err = BATADV_TP_REASON_DST_UNREACHABLE;
		goto out;
	}

err is not used in the out block

Is the last if block supposed to set tp_vars->reason to err?

On Freitag, 28. Oktober 2016 14:13:06 CEST Joe Perches wrote:
> On Thu, 2016-10-27 at 21:01 +0200, Simon Wunderlich wrote:
> > From: Sven Eckelmann <sven@narfation.org>
> > 
> > It must be avoided that arguments to a macro are evaluated ungrouped (which
> > enforces normal operator precendence). Otherwise the result of the macro
> > is not well defined.
> 
> Curiosity:
> 
> in net/batman-adv/tp_meter.c
[...]
> 	orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end);
> 	if (unlikely(!orig_node)) {
> 		err = BATADV_TP_REASON_DST_UNREACHABLE;
> 		tp_vars->reason = err;
> 		goto out;
> 	}
> 
> 	primary_if = batadv_primary_if_get_selected(bat_priv);
> 	if (unlikely(!primary_if)) {
> 		err = BATADV_TP_REASON_DST_UNREACHABLE;
> 		goto out;
> 	}
> 
> err is not used in the out block
> 
> Is the last if block supposed to set tp_vars->reason to err?

This seems to be unrelated to this patch.

But yes, looks to me like it is missing. Do you want to propose a patch or
should I do? Just make sure you Cc Antonio Quartulli <a@unstable.cc> (and of
course b.a.t.m.a.n@lists.open-mesh.org). He is the original author of
33a3bb4a3345 ("batman-adv: throughput meter implementation").

Kind regards,
	Sven

On Fri, 2016-10-28 at 23:27 +0200, Sven Eckelmann wrote:
> On Freitag, 28. Oktober 2016 14:13:06 CEST Joe Perches wrote:
> > On Thu, 2016-10-27 at 21:01 +0200, Simon Wunderlich wrote:
> > > From: Sven Eckelmann <sven@narfation.org>
> > > 
> > > It must be avoided that arguments to a macro are evaluated ungrouped (which
> > > enforces normal operator precendence). Otherwise the result of the macro
> > > is not well defined.
> > 
> > Curiosity:
> > 
> > in net/batman-adv/tp_meter.c
> 
> [...]
> > 	orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end);
> > 	if (unlikely(!orig_node)) {
> > 		err = BATADV_TP_REASON_DST_UNREACHABLE;
> > 		tp_vars->reason = err;
> > 		goto out;
> > 	}
> > 
> > 	primary_if = batadv_primary_if_get_selected(bat_priv);
> > 	if (unlikely(!primary_if)) {
> > 		err = BATADV_TP_REASON_DST_UNREACHABLE;
> > 		goto out;
> > 	}
> > 
> > err is not used in the out block
> > 
> > Is the last if block supposed to set tp_vars->reason to err?
> 
> This seems to be unrelated to this patch.

Kinda.  I was looking at how the one instance of
batadv_tp_is_error was used and it's in this file.

> But yes, looks to me like it is missing. Do you want to propose a patch or
> should I do?

As you are working on this file, perhaps you should.

cheers, Joe

On Freitag, 28. Oktober 2016 18:56:24 CEST Joe Perches wrote:
[...]
> > But yes, looks to me like it is missing. Do you want to propose a patch or
> > should I do?
> 
> As you are working on this file, perhaps you should.

Ok, I will submit a patch with you as Reported-by to
the batman-adv mailing list

Kind regards,
	Sven