netdev - Re: [EXT] Re: [PATCH net-next v4 6/8] octeon_ep: support asynchronous notifications

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Message-ID: <20230329072957.GF831478@unreal>
Date:   Wed, 29 Mar 2023 10:29:57 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Veerasenareddy Burru <vburru@...vell.com>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Abhijit Ayarekar <aayarekar@...vell.com>,
        Sathesh B Edara <sedara@...vell.com>,
        Satananda Burla <sburla@...vell.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Subject: Re: [EXT] Re: [PATCH net-next v4 6/8] octeon_ep: support
 asynchronous notifications

On Thu, Mar 23, 2023 at 05:24:55PM +0000, Veerasenareddy Burru wrote:
> 
> 
> > -----Original Message-----
> > From: Leon Romanovsky <leon@...nel.org>
> > Sent: Thursday, March 23, 2023 3:39 AM
> > To: Veerasenareddy Burru <vburru@...vell.com>
> > Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; Abhijit Ayarekar
> > <aayarekar@...vell.com>; Sathesh B Edara <sedara@...vell.com>;
> > Satananda Burla <sburla@...vell.com>; linux-doc@...r.kernel.org; David S.
> > Miller <davem@...emloft.net>; Eric Dumazet <edumazet@...gle.com>;
> > Jakub Kicinski <kuba@...nel.org>; Paolo Abeni <pabeni@...hat.com>
> > Subject: [EXT] Re: [PATCH net-next v4 6/8] octeon_ep: support
> > asynchronous notifications
> > 
> > External Email
> > 
> > ----------------------------------------------------------------------
> > On Wed, Mar 22, 2023 at 02:19:55AM -0700, Veerasenareddy Burru wrote:
> > > Add asynchronous notification support to the control mailbox.
> > >
> > > Signed-off-by: Veerasenareddy Burru <vburru@...vell.com>
> > > Signed-off-by: Abhijit Ayarekar <aayarekar@...vell.com>
> > > ---
> > > v3 -> v4:
> > >  * 0005-xxx.patch in v3 is 0006-xxx.patch in v4.
> > >  * addressed review comments
> > >    https://urldefense.proofpoint.com/v2/url?u=https-
> > 3A__lore.kernel.org_all_Y-2B0J94sowllCe5Gs-
> > 40boxer_&d=DwIBAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=XkP_75lnbPIeeucsP
> > X36ZgjiMqEKttwZfwNyWMCLjT0&m=5CnsD-
> > SX6ZoW98szwM0k4IXgNC3wY0EwCQHxDKGyNIRUJxdaNe3zorLcOhc9iU6d&s
> > =k73McQSsjbjj87VbCCB8EFFtGWtksMIGhn15RK12XF8&e=
> > >    - fixed rct violation.
> > >    - process_mbox_notify() now returns void.
> > >
> > > v2 -> v3:
> > >  * no change
> > >
> > > v1 -> v2:
> > >  * no change
> > >
> > >  .../marvell/octeon_ep/octep_ctrl_net.c        | 29 +++++++++++++++++++
> > >  1 file changed, 29 insertions(+)
> > >
> > > diff --git a/drivers/net/ethernet/marvell/octeon_ep/octep_ctrl_net.c
> > > b/drivers/net/ethernet/marvell/octeon_ep/octep_ctrl_net.c
> > > index cef4bc3b1ec0..465eef2824e3 100644
> > > --- a/drivers/net/ethernet/marvell/octeon_ep/octep_ctrl_net.c
> > > +++ b/drivers/net/ethernet/marvell/octeon_ep/octep_ctrl_net.c
> > > @@ -271,6 +271,33 @@ static void process_mbox_resp(struct
> > octep_device *oct,
> > >  	}
> > >  }
> > >
> > > +static int process_mbox_notify(struct octep_device *oct,
> > > +			       struct octep_ctrl_mbox_msg *msg) {
> > > +	struct net_device *netdev = oct->netdev;
> > > +	struct octep_ctrl_net_f2h_req *req;
> > > +
> > > +	req = (struct octep_ctrl_net_f2h_req *)msg->sg_list[0].msg;
> > > +	switch (req->hdr.s.cmd) {
> > > +	case OCTEP_CTRL_NET_F2H_CMD_LINK_STATUS:
> > > +		if (netif_running(netdev)) {
> > > +			if (req->link.state) {
> > > +				dev_info(&oct->pdev->dev,
> > "netif_carrier_on\n");
> > > +				netif_carrier_on(netdev);
> > > +			} else {
> > > +				dev_info(&oct->pdev->dev,
> > "netif_carrier_off\n");
> > > +				netif_carrier_off(netdev);
> > > +			}
> > 
> > Shouldn't netdev changes be protected by some lock?
> > Is is safe to get event from FW and process it as is?
> > 
> > Thanks
> 
> Thanks for the kind feedback.
> I do not see netif_carrier_on/off require any protection. I referred few other drivers and do not see such protection used for carrier on/off.
> Please suggest if I am missing something here.

I see that Dave already applied your v5. I think that you are missing context in which you
are running FW commands. They run independently from netdev and makes netif_running() check
to be racy.

Thanks

>