netdev - RE: [PATCH V1 net-next 02/13] net: ena: avoid unnecessary admin command when RSS function set fails

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Message-ID: <18461245e6654647bafa7cbdcb2897bf@EX13D11EUC003.ant.amazon.com>
Date:   Sun, 26 Apr 2020 09:45:19 +0000
From:   "Jubran, Samih" <sameehj@...zon.com>
To:     Jakub Kicinski <kuba@...nel.org>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Kiyanovski, Arthur" <akiyano@...zon.com>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        "Machulsky, Zorik" <zorik@...zon.com>,
        "Matushevsky, Alexander" <matua@...zon.com>,
        "Bshara, Saeed" <saeedb@...zon.com>,
        "Wilson, Matt" <msw@...zon.com>,
        "Liguori, Anthony" <aliguori@...zon.com>,
        "Bshara, Nafea" <nafea@...zon.com>,
        "Tzalik, Guy" <gtzalik@...zon.com>,
        "Belgazal, Netanel" <netanel@...zon.com>,
        "Saidi, Ali" <alisaidi@...zon.com>,
        "Herrenschmidt, Benjamin" <benh@...zon.com>,
        "Dagan, Noam" <ndagan@...zon.com>
Subject: RE: [PATCH V1 net-next 02/13] net: ena: avoid unnecessary admin command when
 RSS function set fails



> -----Original Message-----
> From: Jakub Kicinski <kuba@...nel.org>
> Sent: Thursday, April 23, 2020 3:43 AM
> To: Jubran, Samih <sameehj@...zon.com>
> Cc: davem@...emloft.net; netdev@...r.kernel.org; Kiyanovski, Arthur
> <akiyano@...zon.com>; Woodhouse, David <dwmw@...zon.co.uk>;
> Machulsky, Zorik <zorik@...zon.com>; Matushevsky, Alexander
> <matua@...zon.com>; Bshara, Saeed <saeedb@...zon.com>; Wilson,
> Matt <msw@...zon.com>; Liguori, Anthony <aliguori@...zon.com>;
> Bshara, Nafea <nafea@...zon.com>; Tzalik, Guy <gtzalik@...zon.com>;
> Belgazal, Netanel <netanel@...zon.com>; Saidi, Ali
> <alisaidi@...zon.com>; Herrenschmidt, Benjamin <benh@...zon.com>;
> Dagan, Noam <ndagan@...zon.com>
> Subject: RE: [EXTERNAL] [PATCH V1 net-next 02/13] net: ena: avoid
> unnecessary admin command when RSS function set fails
> 
> CAUTION: This email originated from outside of the organization. Do not click
> links or open attachments unless you can confirm the sender and know the
> content is safe.
> 
> 
> 
> On Wed, 22 Apr 2020 17:39:41 -0700 Jakub Kicinski wrote:
> > On Wed, 22 Apr 2020 08:16:17 +0000 sameehj@...zon.com wrote:
> > > From: Arthur Kiyanovski <akiyano@...zon.com>
> > >
> > > Currently when ena_set_hash_function() fails the hash function is
> > > restored to the previous value by calling an admin command to get
> > > the hash function from the device.
> >
> > I don't see how. func argument is NULL. If I'm reading the code right
> > if this function is restoring anything it's restoring the rss key.
> 
> Ah, my bad, it sets the function in dev->rss, too.
> 
> Please reorganize these changes, they are very poorly split up right now.
> 
> > > In this commit we avoid the admin command, by saving the previous
> > > hash function before calling ena_set_hash_function() and using this
> > > previous value to restore the hash function in case of failure of
> > > ena_set_hash_function().
> > >
> > > Signed-off-by: Sameeh Jubran <sameehj@...zon.com>
> > > Signed-off-by: Arthur Kiyanovski <akiyano@...zon.com>
> > > ---
> > >  drivers/net/ethernet/amazon/ena/ena_com.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c
> > > b/drivers/net/ethernet/amazon/ena/ena_com.c
> > > index 07b0f396d3c2..66edc86c41c9 100644
> > > --- a/drivers/net/ethernet/amazon/ena/ena_com.c
> > > +++ b/drivers/net/ethernet/amazon/ena/ena_com.c
> > > @@ -2286,6 +2286,7 @@ int ena_com_fill_hash_function(struct
> ena_com_dev *ena_dev,
> > >     struct ena_admin_get_feat_resp get_resp;
> > >     struct ena_admin_feature_rss_flow_hash_control *hash_key =
> > >             rss->hash_key;
> > > +   enum ena_admin_hash_functions old_func;
> > >     int rc;
> > >
> > >     /* Make sure size is a mult of DWs */ @@ -2325,12 +2326,13 @@
> > > int ena_com_fill_hash_function(struct ena_com_dev *ena_dev,
> > >             return -EINVAL;
> > >     }
> > >
> > > +   old_func = rss->hash_func;
> > >     rss->hash_func = func;
> > >     rc = ena_com_set_hash_function(ena_dev);
> > >
> > >     /* Restore the old function */
> > >     if (unlikely(rc))
> > > -           ena_com_get_hash_function(ena_dev, NULL, NULL);
> > > +           rss->hash_func = old_func;
> >
> > Please order your commits correctly.
You are right, the order of the commits is not ideal, will fix in v2.
> >
> > >     return rc;
> > >  }