netdev - Re: [PATCH net 1/1] ixgbe: Add locking to prevent panic when setting sriov

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Date:   Mon, 16 Aug 2021 17:52:43 +0000
From:   "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>
To:     "kuba@...nel.org" <kuba@...nel.org>
CC:     "jkc@...hat.com" <jkc@...hat.com>,
        "Szlosek, Marek" <marek.szlosek@...el.com>,
        "Yang, Lihong" <lihong.yang@...el.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Venkataramanan, Anirudh" <anirudh.venkataramanan@...el.com>
Subject: Re: [PATCH net 1/1] ixgbe: Add locking to prevent panic when setting
 sriov_numvfs to zero

On Fri, 2021-08-13 at 17:20 -0700, Jakub Kicinski wrote:
> On Thu, 12 Aug 2021 10:18:56 -0700 Tony Nguyen wrote:
> > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> > b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> > index 214a38de3f41..0a1a8756f1fd 100644
> > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c
> > @@ -206,8 +206,12 @@ int ixgbe_disable_sriov(struct ixgbe_adapter
> > *adapter)
> >  	unsigned int num_vfs = adapter->num_vfs, vf;
> >  	int rss;
> >  
> > +	while (test_and_set_bit(__IXGBE_DISABLING_VFS, &adapter-
> > >state))
> > +		usleep_range(1000, 2000);
> > +
> >  	/* set num VFs to 0 to prevent access to vfinfo */
> >  	adapter->num_vfs = 0;
> > +	clear_bit(__IXGBE_DISABLING_VFS, &adapter->state);
> >  
> >  	/* put the reference to all of the vf devices */
> >  	for (vf = 0; vf < num_vfs; ++vf) {
> > @@ -1307,6 +1311,9 @@ void ixgbe_msg_task(struct ixgbe_adapter
> > *adapter)
> >  	struct ixgbe_hw *hw = &adapter->hw;
> >  	u32 vf;
> >  
> > +	if (test_and_set_bit(__IXGBE_DISABLING_VFS, &adapter->state))
> > +		return;
> > +
> >  	for (vf = 0; vf < adapter->num_vfs; vf++) {
> >  		/* process any reset requests */
> >  		if (!ixgbe_check_for_rst(hw, vf))
> > @@ -1320,6 +1327,7 @@ void ixgbe_msg_task(struct ixgbe_adapter
> > *adapter)
> >  		if (!ixgbe_check_for_ack(hw, vf))
> >  			ixgbe_rcv_ack_from_vf(adapter, vf);
> >  	}
> > +	clear_bit(__IXGBE_DISABLING_VFS, &adapter->state);
> 
> Like I've already said two or three times. No flag based locking.

Ken,

Did you want to make this change or did you want Intel to do it?

Thanks,
Tony