On Thu, Jan 12, 2017 at 04:58:28PM -0500, Doug Ledford wrote:
> On Thu, 2017-01-12 at 21:35 +0200, Leon Romanovsky wrote:
> > 
> > First of all, thank you for fixing wording, for me it is the hardest
> > part of every commit.
>
> No worries.
>
> > Second, I have a different view from you on the issue. User
> > configured
> > some value, which is not correct for IPoIB. In ideal world (without
> > legacy),
> > we were supposed to return error to him with proper message,
>
> If you set an impossible MTU on an ethernet adapter, you get a return
> of EINVAL.  But it doesn't mess with the kernel log at all, it's *just*
> EINVAL to the calling program.
>
> >  but in our
> > case (legacy applications) we can't (we tried and it broke some
> > legacy
> > ifcongfig, if I remember well).
>
> ifconfig is what I used to test what Ethernet does, so it should be
> well and truly used to EINVAL as a return.

I'll recheck with Feras next week which legacy tool
didn't work and will post it.

>
> >  So it leaves us with one available
> > option is to warn user about improper value.
>
> Even if you want to alert the user, there is no need to warn.  Warn is
> reserved for something that is a serious error or condition, this is an
> EINVAL of something that is, at best, a performance issue.  Unless path
> MTU support is broken, failing to set a larger MTU will not ever hinder
> actual operation.  So we should never be dumping out KERN_WARN messages
> into the kernel log that will ping up on any root login session as well
> as clutter the kernel dmesg output.
>
> > User should know that he supplied wrong parameter.
>
> User can still find out, they just won't get proactive pings on all
> root sessions, instead they will have to look in the dmesg output
> because they are trying to figure out why their command didn't work.
>
> > >
> > >
> > > --
> > > Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> > >     GPG KeyID: B826A3330E572FDD
> > >    
> > > Key fingerprint = AE6B 1BDA 122B 23B4 265B  1274 B826 A333 0E57
> > > 2FDD
> >
> >
> --
> Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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>    
> Key fingerprint = AE6B 1BDA 122B 23B4 265B  1274 B826 A333 0E57 2FDD