Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 5 Apr 2023 15:04:39 +0200
From:   Simon Horman <simon.horman@corigine.com>
To:     Denis Plotnikov <den-plotnikov@yandex-team.ru>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        shshaikh@marvell.com, manishc@marvell.com,
        GR-Linux-NIC-Dev@marvell.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
        Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org
Subject: Re: [PATCH] qlcnic: check pci_reset_function result
Message-ID: <ZC1x57v1JdUyK7aG@corigine.com>
References: <20230331080605.42961-1-den-plotnikov@yandex-team.ru>
 <ZCcd1c0jhKxk+FD+@corigine.com>
 <b4852db1-61bd-410e-e89d-05d89cf14063@yandex-team.ru>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <b4852db1-61bd-410e-e89d-05d89cf14063@yandex-team.ru>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?1YRNznjZMTeknzq2yh6fyj+kovxBT38nM+zav5WS6JZJa41hihPLXWjRvBEd?=
 =?us-ascii?Q?E6MNFQulaCVzGwuCbs/9wWAO2mWZtvHJJw3hZYuBg8sJsYUcyDDhkAj0oot7?=
 =?us-ascii?Q?U5GvCszTVyPv+iQVb1r1ag8ZxBk7VHWkyECwO7PK1/M72xKkniWkn197Yvi1?=
 =?us-ascii?Q?yFDRB5jgpD/SLOv8xrIwn1FfE9kzUhtU78PeE8ruEoLVL4yI1gePKQkTNA8U?=
 =?us-ascii?Q?8gJvLV6Yikr6M8IitQ9xyAvp9NI5Ayh61uCEkJ0lk0SFIr9SyvhcTY0ZyUj8?=
 =?us-ascii?Q?flPDsOI2I8jivaUN0Xj4YjiucXTnt7C5Zo+GvW9g9pf/PDRnJVMYT2oZckk8?=
 =?us-ascii?Q?KznrgdXshegVVuBKcbEvVNzEA95+gB64BZWGqQBOWN/c9o0QO95Kpv/EgPdS?=
 =?us-ascii?Q?1Xo1o+jddYClryopxl/OdfaJeIVCxfcGXWix9vEALw8tTAUue85Y2dyjeIsO?=
 =?us-ascii?Q?LOP9afR+wpUN5OvkuKlblbf2sxucCM8aZfN34rwudaPEeS0QvEJ9SP1adYWr?=
 =?us-ascii?Q?zx/kQbJvGIECDf+t4jNsf8Htw7IFGiRjcX3hebGCYca8ZtzLVh69XFTemvfn?=
 =?us-ascii?Q?prHayLwZdbkKChod+C0ETN6hwOjOp0R/MrqUuZOCOOpqmt0uCqTaKM0rjiKZ?=
 =?us-ascii?Q?bkp4OO1hznIcmEHAozjQRLq/ilo1KnejWelZ9HNzIg1REvjX9GrTnHVCBxzI?=
 =?us-ascii?Q?fRrQRzCQSMAzAsVEW+l9f8+Z7QKgKeYIQ0KN7gdp6t9QuzFJyAb5CXpEZ1ZE?=
 =?us-ascii?Q?Nrb4luLWEjuE3k6RSe53Ho1+UoIHJOFNvyuqK8vWoO204f6TTJ4TpwHJpr/j?=
 =?us-ascii?Q?OS8qrZko+EDAQvjx9J2h3wV4ll4Jfn9ho26eBYRHIEUdcHKn1SAEi8yLR6SS?=
 =?us-ascii?Q?058SMNx59K9bDz2Letgllb0Nhx5ET9VJnRDYul+X9RFeKqdlVdmIQ9O3xno0?=
 =?us-ascii?Q?iSFn2cU+UqN0qxyERPpmmDVx1HJKpcEjwdp7AXMjlO9MCus2iBjaRw2+lnJr?=
 =?us-ascii?Q?CUSgbJ8xLrb7v5rjN2KyuvPU2v6VBchTstSp2jVd4gQKc3hNwFi2HJ3QKEqR?=
 =?us-ascii?Q?pmUVaMkBangP+QzTvrG4nl4WQqdcGeuGDQ/A5g+cwipiUWiszfB5eXZyemCC?=
 =?us-ascii?Q?VnMjJikbpKEpQEqNEfh0IlVk6Mu4dAayHuMp1VYRbGGCFUG0oVTrRwoM+ynJ?=
 =?us-ascii?Q?4M00maixC+lf0IyCHE5VSjI1MEJeIdAehGbcGzeSwyM8VnwjsGr8y+zZNUjc?=
 =?us-ascii?Q?g8prRv7nWDeYIpAedy/NtD1gh2iUool6cJYWmV0E/QNwm2lqzDDAintiIF3Z?=
 =?us-ascii?Q?T9GYdgda5/TvCChWcc0Sdt1zIHbG1/rain0W3bPkC48GXvsCD2ZV3lSUMLM3?=
 =?us-ascii?Q?eZMJBWI155uvCsqCTXOyIcjly/00+j8lTvZfjG2iuZ1IWys69m8iFuo/i1MJ?=
 =?us-ascii?Q?cWnBWmhWXgD0F8z9uNbXpFmJZWth9LK+8BcKElhnFxm4hwQVQD72x7Xk5NIn?=
 =?us-ascii?Q?5SkZZF94uy/Gpha9R/Ft5TJ1g665NDKOXL6eD1tu+zsT9ro7lG+nOcRpLA+P?=
 =?us-ascii?Q?n66UNfpib0Qrdr/ewoFBqgRXB7tw9hayXzvsrBMajAF/dvCWGz5VIhOfM8oh?=
 =?us-ascii?Q?Y3sbn+ntksrVb/Out25RRSgvH4Mh9QxvR+EkSfcULnR06LaY+pa0Gikl+Vpg?=
 =?us-ascii?Q?pS/3Pw=3D=3D?=
X-OriginatorOrg: corigine.com
X-MS-Exchange-CrossTenant-Network-Message-Id: dacdffa0-ee69-4489-ddb1-08db35d65508
X-MS-Exchange-CrossTenant-AuthSource: PH0PR13MB4842.namprd13.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Apr 2023 13:04:47.0966
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: fe128f2c-073b-4c20-818e-7246a585940c
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: FNVylMJVNJzMMlRFvCWLQ39gVEy/b1y2wblPbleQJVMk0Fwc2/5+jXH30VV/+2GZFlBTcuNjPy5OG126WV5nzr91mzTWgMkKqZiRWyWPsgM=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY1PR13MB6189
X-Spam-Status: No, score=-0.0 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
        RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS
        autolearn=unavailable autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

+ Bjorn Helgaas and linux-pci, as this is about FLR

On Mon, Apr 03, 2023 at 01:58:49PM +0300, Denis Plotnikov wrote:
> 
> On 31.03.2023 20:52, Simon Horman wrote:
> > On Fri, Mar 31, 2023 at 11:06:05AM +0300, Denis Plotnikov wrote:
> > > Static code analyzer complains to unchecked return value.
> > > It seems that pci_reset_function return something meaningful
> > > only if "reset_methods" is set.
> > > Even if reset_methods isn't used check the return value to avoid
> > > possible bugs leading to undefined behavior in the future.
> > > 
> > > Signed-off-by: Denis Plotnikov <den-plotnikov@yandex-team.ru>
> > nit: The tree this patch is targeted at should be designated, probably
> >       net-next, so the '[PATCH net-next]' in the subject.
> > 
> > > ---
> > >   drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c | 4 +++-
> > >   1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c
> > > index 87f76bac2e463..39ecfc1a1dbd0 100644
> > > --- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c
> > > +++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c
> > > @@ -628,7 +628,9 @@ int qlcnic_fw_create_ctx(struct qlcnic_adapter *dev)
> > >   	int i, err, ring;
> > >   	if (dev->flags & QLCNIC_NEED_FLR) {
> > > -		pci_reset_function(dev->pdev);
> > > +		err = pci_reset_function(dev->pdev);
> > > +		if (err && err != -ENOTTY)
> > Are you sure about the -ENOTTY part?
> > 
> > It seems odd to me that an FLR would be required but reset is not supported.
> No, I'm not sure. My logic is: if the reset method isn't set than
> pci_reset_function() returns -ENOTTY so treat that result as ok.
> pci_reset_function may return something different than -ENOTTY only if
> pci_reset_fn_methods[m].reset_fn is set.

I see your reasoning: -ENOTTY means nothing happened, and probably that is ok.
I think my main question is if that can ever happen.
If that is unknown, then I think this conservative approach makes sense.

Bjorn, do you happen to have any guidance here?

> > > +			return err;
> > >   		dev->flags &= ~QLCNIC_NEED_FLR;
> > >   	}
> > > -- 
> > > 2.25.1
> > >