linux-kernel - Re: [PATCH vhost 2/2] vdpa/mlx5: Fix suboptimal range on iotlb iteration

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Message-ID: <20241113100618-mutt-send-email-mst@kernel.org>
Date: Wed, 13 Nov 2024 10:06:24 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Dragos Tatulea <dtatulea@...dia.com>
Cc: virtualization@...ts.linux.dev, Si-Wei Liu <si-wei.liu@...cle.com>,
	Jason Wang <jasowang@...hat.com>,
	Eugenio Perez Martin <eperezma@...hat.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Gal Pressman <gal@...dia.com>,
	Parav Pandit <parav@...dia.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Subject: Re: [PATCH vhost 2/2] vdpa/mlx5: Fix suboptimal range on iotlb
 iteration

On Wed, Nov 13, 2024 at 04:01:05PM +0100, Dragos Tatulea wrote:
> 
> 
> On 13.11.24 15:49, Michael S. Tsirkin wrote:
> > On Wed, Nov 13, 2024 at 03:33:35PM +0100, Dragos Tatulea wrote:
> >>
> >>
> >> On 13.11.24 07:32, Michael S. Tsirkin wrote:
> >>> On Mon, Oct 21, 2024 at 04:40:40PM +0300, Dragos Tatulea wrote:
> >>>> From: Si-Wei Liu <si-wei.liu@...cle.com>
> >>>>
> >>>> The starting iova address to iterate iotlb map entry within a range
> >>>> was set to an irrelevant value when passing to the itree_next()
> >>>> iterator, although luckily it doesn't affect the outcome of finding
> >>>> out the granule of the smallest iotlb map size. Fix the code to make
> >>>> it consistent with the following for-loop.
> >>>>
> >>>> Fixes: 94abbccdf291 ("vdpa/mlx5: Add shared memory registration code")
> >>>
> >>>
> >>> But the cover letter says "that's why it does not have a fixes tag".
> >>> Confused.
> >> Sorry about that. Patch is fine with fixes tag, I forgot to drop that
> >> part of the sentence from the cover letter.
> >>
> >> Let me know if I need to resend something.
> >>
> >> Thanks,
> >> Dragos
> > 
> > But why does it need the fixes tag? That one means "if you have
> > that hash, you need this patch". Pls do not abuse it for
> > optimizations.
> > 
> Well, it is a fix but it happens that the code around still works without
> this fix. I figured that it would be better to take it into older stable kernels
> just like the other one. But if you consider it an improvement I will send a v2
> without the Fixes tag.
> 
> Thanks,
> Dragos

No need.