linux-kernel - Re: [PATCH] staging: lustre: o2iblnd: Stop MLX5 triggering a dump

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Date:   Mon, 19 Mar 2018 11:14:33 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Doug Oucharek <dougso@...com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org, "Drokin, Oleg" <oleg.drokin@...el.com>,
        "Dilger, Andreas" <andreas.dilger@...el.com>,
        James Simmons <jsimmons@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lustre Development List <lustre-devel@...ts.lustre.org>
Subject: Re: [PATCH] staging: lustre: o2iblnd: Stop MLX5 triggering a dump_cqe

I don't really understand this patch...

On Fri, Mar 16, 2018 at 04:40:21PM -0700, Doug Oucharek wrote:
> We have found that MLX5 will trigger a dump_cqe if we don't
> invalidate the rkey on a newly alloated MR for FastReg usage.
> 
> This fix just tags the MR as invalid on its creation if we are
> using FastReg and that will force it to do an invalidate of the
> rkey on first usage.

This paragraph makes the change seem like a limited workaround for a
bug in the MLX5 code.  Why can't the MLX5 code be fixed instead?

Looking at the patch it doesn't seem like a limitted solution at all.
Now frd->frd_valid is *always* set to false.  Why don't we instead just
delete ->frd_valid along with the newly dead code?

regards,
dan carpenter