On Fri, Jun 22, 2012 at 10:17:23AM +0300, Kalle Valo wrote:
> Rajkumar Manoharan <rmanohar@xxxxxxxxxxxxxxxx> writes:
>
> > ath9k_get_et_stats() warn: side effect in macro
> > 'AWDATA' doing 'i++'
> >
> > Cc: Ben Greear <greearb@xxxxxxxxxxxxxxx>
> > Signed-off-by: Rajkumar Manoharan <rmanohar@xxxxxxxxxxxxxxxx>
>
> [...]
>
> > do { \
> > - data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BE)].elem; \
> > - data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BK)].elem; \
> > - data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VI)].elem; \
> > - data[i++] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VO)].elem; \
> > + data[i+0] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BE)].elem; \
> > + data[i+1] = sc->debug.stats.txstats[PR_QNUM(WME_AC_BK)].elem; \
> > + data[i+2] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VI)].elem; \
> > + data[i+3] = sc->debug.stats.txstats[PR_QNUM(WME_AC_VO)].elem; \
> > + i += 4; \
> > } while (0)
>
> I agree with Ben, this is a useless change as the end result is still
> the same (the side effect is that i is increased with four). You are
> just hiding that from smatch and once smatch is fixed it will warn again
> about the same thing.
>
> I recommend fixing this properly so that the macro doesn't have any side
> effects.
Uh. Sorry, also I thought I had pushed a fix to add this to the
ignored macro list, but I forgot. I've pushed it now.
I don't think this check has ever found a bug. These bugs are very
rare and we are careful about macro side effects in the kernel. I
have disabled the check by default and it's only enabled when you
pass --spammy. I told the Ruby people I was going to do this
earlier in the week but I've been out of the office and delayed.
regards,
dan carpenter
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