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

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Message-Id: <20220630100839.14079-1-piotrx.skajewski@intel.com>
Date:   Thu, 30 Jun 2022 12:08:39 +0200
From:   Piotr Skajewski <piotrx.skajewski@...el.com>
To:     kuba@...nel.org
Cc:     anthony.l.nguyen@...el.com, davem@...emloft.net,
        edumazet@...gle.com, konrad0.jankowski@...el.com,
        netdev@...r.kernel.org, pabeni@...hat.com,
        piotrx.skajewski@...el.com
Subject: Re: [PATCH net 1/1] ixgbe: Add locking to prevent panic when setting sriov_numvfs to zero

On Tue, 28 Jun 2022 10:27:07 -0700 Jakub Kicinski wrote:
> On Tue, 28 Jun 2022 09:53:46 -0700 Tony Nguyen wrote:
> > +	spin_lock_irqsave(&adapter->vfs_lock, flags);
> > +
> >  	/* set num VFs to 0 to prevent access to vfinfo */
> >  	adapter->num_vfs = 0;
> >  
> > @@ -228,6 +231,8 @@ int ixgbe_disable_sriov(struct ixgbe_adapter *adapter)
> >  	kfree(adapter->mv_list);
> >  	adapter->mv_list = NULL;
> >  
> > +	spin_unlock_irqrestore(&adapter->vfs_lock, flags);
>
> There's a pci_dev_put() in there, are you sure it won't sleep?

Thank Jakub for your notice, during development we were aware about this
and tests we've made on this particular case, did not report any problems
that could be related to might_sleep in conjunction with spinlock.