[PATCH] nvme/pci: Print invalid SGL only once

[keith.busch@intel.com (Keith Busch)]

On Fri, Sep 15, 2017@04:55:53PM +0200, Christoph Hellwig wrote:
> On Thu, Sep 14, 2017@03:06:14PM -0400, Keith Busch wrote:
> > The WARN_ONCE macro returns true if the condition is true, not if the
> > warn was raised, so we're printing the scatter list every time it's
> > invalid. This is excessive and makes debugging harder, so this patch
> > prints it just once.
> 
> Please use the printk_ratelimited() helper instead.

Hmm, I don't want to rate limit the prints. That may log only partial
SGLs, or even worse, interleave parts from multiple errors. We want
to see an entire SGL for a single error, like what WARN_ONCE does.
A single occurrence is usually sufficient to work backwards to see how
the breakage occurred.