netdev - RE: [PATCH net-next 7/8] ionic: Use an u16 for rx

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Date: Tue, 18 Jun 2024 08:16:15 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Brett Creeley' <bcreeley@....com>, 'Shannon Nelson'
	<shannon.nelson@....com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>, "kuba@...nel.org"
	<kuba@...nel.org>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"pabeni@...hat.com" <pabeni@...hat.com>
CC: "brett.creeley@....com" <brett.creeley@....com>, "drivers@...sando.io"
	<drivers@...sando.io>
Subject: RE: [PATCH net-next 7/8] ionic: Use an u16 for rx_copybreak

From: Brett Creeley
> Sent: 17 June 2024 17:25
> 
> On 6/15/2024 2:20 PM, David Laight wrote:
> >
> > From: Shannon Nelson
> >> Sent: 11 June 2024 00:07
> >>
> >> From: Brett Creeley <brett.creeley@....com>
> >>
> >> To make space for other data members on the first cache line reduce
> >> rx_copybreak from an u32 to u16.  The max Rx buffer size we support
> >> is (u16)-1 anyway so this makes sense.
> >>
> >> Signed-off-by: Brett Creeley <brett.creeley@....com>
> >> Signed-off-by: Shannon Nelson <shannon.nelson@....com>
> >> ---
> >>   drivers/net/ethernet/pensando/ionic/ionic_ethtool.c | 10 +++++++++-
> >>   drivers/net/ethernet/pensando/ionic/ionic_lif.h     |  2 +-
> >>   2 files changed, 10 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/net/ethernet/pensando/ionic/ionic_ethtool.c
> >> b/drivers/net/ethernet/pensando/ionic/ionic_ethtool.c
> >> index 91183965a6b7..26acd82cf6bc 100644
> >> --- a/drivers/net/ethernet/pensando/ionic/ionic_ethtool.c
> >> +++ b/drivers/net/ethernet/pensando/ionic/ionic_ethtool.c
> >> @@ -872,10 +872,18 @@ static int ionic_set_tunable(struct net_device *dev,
> >>                             const void *data)
> >>   {
> >>        struct ionic_lif *lif = netdev_priv(dev);
> >> +     u32 rx_copybreak, max_rx_copybreak;
> >>
> >>        switch (tuna->id) {
> >>        case ETHTOOL_RX_COPYBREAK:
> >> -             lif->rx_copybreak = *(u32 *)data;
> >> +             rx_copybreak = *(u32 *)data;
> >> +             max_rx_copybreak = min_t(u32, U16_MAX, IONIC_MAX_BUF_LEN);
> >
> > I doubt that needs to be min_t() or that you really need the temporary.
> 
> IMHO the temporary variable here makes it more readable than comparing
> directly to the casted/de-referenced opaque data pointer and then
> assigning to the rx_copybreak member if it's a valid value.
...

I was thinking of the temporary for the result of min().

	David

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