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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: "Leon Romanovsky" <leon@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Saeed Mahameed" <saeedm@nvidia.com>,
	"Jason Gunthorpe" <jgg@nvidia.com>,
	"Alexander Duyck" <alexander.duyck@gmail.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	linux-pci@vger.kernel.org, linux-rdma@vger.kernel.org,
	netdev@vger.kernel.org, "Don Dutile" <ddutile@redhat.com>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"David S . Miller" <davem@davemloft.net>,
	"Krzysztof Wilczyński" <kw@linux.com>
Subject: Re: [PATCH mlx5-next v6 1/4] PCI: Add sysfs callback to allow MSI-X table size change of SR-IOV VFs
Date: Wed, 24 Feb 2021 09:09:09 +0100	[thread overview]
Message-ID: <YDYJpTaxXL4ESwZS@kroah.com> (raw)
In-Reply-To: <20210223210743.GA1475710@bjorn-Precision-5520>

On Tue, Feb 23, 2021 at 03:07:43PM -0600, Bjorn Helgaas wrote:
> On Sun, Feb 21, 2021 at 08:59:18AM +0200, Leon Romanovsky wrote:
> > On Sat, Feb 20, 2021 at 01:06:00PM -0600, Bjorn Helgaas wrote:
> > > On Fri, Feb 19, 2021 at 09:20:18AM +0100, Greg Kroah-Hartman wrote:
> > >
> > > > Ok, can you step back and try to explain what problem you are trying to
> > > > solve first, before getting bogged down in odd details?  I find it
> > > > highly unlikely that this is something "unique", but I could be wrong as
> > > > I do not understand what you are wanting to do here at all.
> > >
> > > We want to add two new sysfs files:
> > >
> > >   sriov_vf_total_msix, for PF devices
> > >   sriov_vf_msix_count, for VF devices associated with the PF
> > >
> > > AFAICT it is *acceptable* if they are both present always.  But it
> > > would be *ideal* if they were only present when a driver that
> > > implements the ->sriov_get_vf_total_msix() callback is bound to the
> > > PF.
> > 
> > BTW, we already have all possible combinations: static, static with
> > folder, with and without "sriov_" prefix, dynamic with and without
> > folders on VFs.
> > 
> > I need to know on which version I'll get Acked-by and that version I
> > will resubmit.
> 
> I propose that you make static attributes for both files, so
> "sriov_vf_total_msix" is visible for *every* PF in the system and
> "sriov_vf_msix_count" is visible for *every* VF in the system.
> 
> The PF "sriov_vf_total_msix" show function can return zero if there's
> no PF driver or it doesn't support ->sriov_get_vf_total_msix().
> (Incidentally, I think the documentation should mention that when it
> *is* supported, the contents of this file are *constant*, i.e., it
> does not decrease as vectors are assigned to VFs.)
> 
> The "sriov_vf_msix_count" set function can ignore writes if there's no
> PF driver or it doesn't support ->sriov_get_vf_total_msix(), or if a
> VF driver is bound.
> 
> Any userspace software must be able to deal with those scenarios
> anyway, so I don't think the mere presence or absence of the files is
> a meaningful signal to that software.

Hopefully, good luck with that!

> If we figure out a way to make the files visible only when the
> appropriate driver is bound, that might be nice and could always be
> done later.  But I don't think it's essential.

That seems reasonable, feel free to cc: me on the next patch series and
I'll try to review it, which should make more sense to me than this
email thread :)

thanks,

greg k-h

  reply	other threads:[~2021-02-24  8:09 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-09 13:34 [PATCH mlx5-next v6 0/4] Dynamically assign MSI-X vectors count Leon Romanovsky
2021-02-09 13:34 ` [PATCH mlx5-next v6 1/4] PCI: Add sysfs callback to allow MSI-X table size change of SR-IOV VFs Leon Romanovsky
2021-02-15 21:01   ` Bjorn Helgaas
2021-02-16  7:33     ` Leon Romanovsky
2021-02-16 16:12       ` Bjorn Helgaas
2021-02-16 19:58         ` Leon Romanovsky
2021-02-17 18:02           ` Bjorn Helgaas
2021-02-17 19:25             ` Jason Gunthorpe
2021-02-17 20:28               ` Bjorn Helgaas
2021-02-17 23:52                 ` Jason Gunthorpe
2021-02-18 10:15             ` Leon Romanovsky
2021-02-18 22:39               ` Bjorn Helgaas
2021-02-19  7:52                 ` Leon Romanovsky
2021-02-19  8:20                   ` Greg Kroah-Hartman
2021-02-19 16:58                     ` Leon Romanovsky
2021-02-20 19:06                     ` Bjorn Helgaas
2021-02-21  6:59                       ` Leon Romanovsky
2021-02-23 21:07                         ` Bjorn Helgaas
2021-02-24  8:09                           ` Greg Kroah-Hartman [this message]
2021-02-24 21:37                             ` Don Dutile
2021-02-24  9:53                           ` Leon Romanovsky
2021-02-24 15:07                             ` Bjorn Helgaas
2021-02-21 13:00                       ` Greg Kroah-Hartman
2021-02-21 13:55                         ` Leon Romanovsky
2021-02-21 15:01                           ` Greg Kroah-Hartman
2021-02-21 15:30                             ` Leon Romanovsky
2021-02-16 20:37         ` Jason Gunthorpe
2021-02-09 13:34 ` [PATCH mlx5-next v6 2/4] net/mlx5: Add dynamic MSI-X capabilities bits Leon Romanovsky
2021-02-09 13:34 ` [PATCH mlx5-next v6 3/4] net/mlx5: Dynamically assign MSI-X vectors count Leon Romanovsky
2021-02-09 13:34 ` [PATCH mlx5-next v6 4/4] net/mlx5: Allow to the users to configure number of MSI-X vectors Leon Romanovsky
2021-02-09 21:06 ` [PATCH mlx5-next v6 0/4] Dynamically assign MSI-X vectors count Alexander Duyck
2021-02-14  5:24   ` Leon Romanovsky

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