Re: [PATCH 2/2] IB/ipoib: Suppress warning for send only join failures

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Tue, Aug 25, 2015 at 08:59:13AM -0400, Hal Rosenstock wrote:
> > -		if (mcast->logcount++ < 20) {
> > -			if (status == -ETIMEDOUT || status == -EAGAIN) {
> > +		bool silent_fail =
> > +		    test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) &&
> > +		    status == -EINVAL;
> 
> Aren't there other reasons that send only join might have EINVAL
> indicated ?

Not sure, the layers below all eat the detailed error code. Hopefully
EINVAL isn't re-used.

> Maybe it's better to be overly silent rather than overly
> verbose as to not spam the log but it seems like it would make debug of
> such cases harder.

It makes debugging harder to have worthless messages because they
obscure what is going on. The first time I saw this I assumed there
was an issue, but it turns out to be an expected failure.

The other issue is the way the rate limiting works:

> > +		if (mcast->logcount < 20) {
> > +			if (status == -ETIMEDOUT || status == -EAGAIN ||
> > +			    silent_fail) {
> >  				ipoib_dbg_mcast(priv, "%smulticast join failed for %pI6, status %d\n",
> >  						test_bit(IPOIB_MCAST_FLAG_SENDONLY, &mcast->flags) ? "sendonly " : "",
> >  						mcast->mcmember.mgid.raw, status);

So wasting logcount with expected failures just results in eating
unexpected failures...

> ipoib_dbg_mcast logging is conditionalized on CONFIG_INFINIBAND_IPOIB_DEBUG

Most distros turn this off so the change only impacts people trying to
debug this stuff.

Jason
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