From: "Creeley, Brett" <brett.creeley@intel.com>
To: Arkady Gilinsky <arkady.gilinsky@harmonicinc.com>,
"intel-wired-lan@lists.osuosl.org"
<intel-wired-lan@lists.osuosl.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>
Cc: Arkady Gilinsky <arcadyg@gmail.com>
Subject: RE: [EXTERNAL] RE: [PATCH net] i40e/iavf: Fix msg interface between VF and PF
Date: Tue, 5 Nov 2019 16:55:32 +0000 [thread overview]
Message-ID: <3508A0C5D531054DBDD98909F6FA64FA11B39863@ORSMSX113.amr.corp.intel.com> (raw)
In-Reply-To: <1572931430.13810.227.camel@harmonicinc.com>
> -----Original Message-----
> From: Arkady Gilinsky <arkady.gilinsky@harmonicinc.com>
> Sent: Monday, November 4, 2019 9:24 PM
> To: Creeley, Brett <brett.creeley@intel.com>; intel-wired-lan@lists.osuosl.org; netdev@vger.kernel.org; Kirsher, Jeffrey T
> <jeffrey.t.kirsher@intel.com>
> Cc: Arkady Gilinsky <arcadyg@gmail.com>
> Subject: Re: [EXTERNAL] RE: [PATCH net] i40e/iavf: Fix msg interface between VF and PF
> > static bool i40e_vc_verify_vqs_bitmaps(struct virtchnl_queue_select *vqs)
> > {
> > /* this will catch any changes made to the virtchnl_queue_select bitmap */
> > if (sizeof(vqs->rx_queues) != sizeof(u32) ||
> > sizeof(vqs->tx_queues) != sizeof(u32))
> > return false;
> If so, then is it better to check the type of the fields in compile-time rather than in runtime ?
> Something like this:
> BUILD_BUG_ON(sizeof(vqs->rx_queues) != sizeof(u32));
> BUILD_BUG_ON(sizeof(vqs->tx_queues) != sizeof(u32));
> This is not required comparison each time when function is called and made code more optimized.
I don't think this is required with the change you suggested below.
> >
> > if ((vqs->rx_queues == 0 && vqs->tx_queues == 0) ||
> > hweight32(vqs->rx_queues) > I40E_MAX_VF_QUEUES ||
> > hweight32(vqs->tx_queues) > I40E_MAX_VF_QUEUES)
> > return false;
> Again, from optimization POV it is better to have constant changed than variable,
> since it is compile time and not run time action:
> if ((vqs->rx_queues == 0 && vqs->tx_queues == 0) ||
> vqs->rx_queues >= (BIT(I40E_MAX_VF_QUEUES)) ||
>
> vqs->tx_queues >= (BIT(I40E_MAX_VF_QUEUES)))
> return false;
This seems much better than my solution. It fixes the original issue, handles if the
vqs->[r|t]x_queues variables have changed in size, and the queue bitmap comparison
uses a constant. Thanks!
> > return true;
> > }
next prev parent reply other threads:[~2019-11-05 16:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-04 5:32 [PATCH net] i40e/iavf: Fix msg interface between VF and PF Arkady Gilinsky
2019-11-04 23:43 ` Creeley, Brett
2019-11-05 5:23 ` [EXTERNAL] " Arkady Gilinsky
2019-11-05 16:55 ` Creeley, Brett [this message]
2019-11-06 5:30 ` Arkady Gilinsky
2019-11-07 19:38 ` Jeff Kirsher
2019-11-08 16:43 ` Creeley, Brett
2019-11-12 7:33 ` Arkady Gilinsky
2019-11-13 18:47 ` Jeff Kirsher
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