Re: [PATCH net-next] bonding: don't init workqueues on error

From: Matteo Croce
Date: Sat Dec 14 2019 - 08:15:01 EST


On Sat, Dec 14, 2019 at 3:11 AM Jakub Kicinski
<jakub.kicinski@xxxxxxxxxxxxx> wrote:
>
> On Tue, 10 Dec 2019 16:24:54 +0100, Matteo Croce wrote:
> > bond_create() initialize six workqueues used later on.
>
> Work _entries_ not _queues_ no?
>

Right

> > In the unlikely event that the device registration fails, these
> > structures are initialized unnecessarily, so move the initialization
> > out of the error path. Also, create an error label to remove some
> > duplicated code.
>
> Does the initialization of work entries matter? Is this prep for further
> changes?
>

Not a big issue, I just found useless to initialize those data and
free a bit later.
Just a cleanup.

> > Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>
> > ---
> > drivers/net/bonding/bond_main.c | 11 +++++++----
> > 1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> > index fcb7c2f7f001..8756b6a023d7 100644
> > --- a/drivers/net/bonding/bond_main.c
> > +++ b/drivers/net/bonding/bond_main.c
> > @@ -4889,8 +4889,8 @@ int bond_create(struct net *net, const char *name)
> > bond_setup, tx_queues);
> > if (!bond_dev) {
> > pr_err("%s: eek! can't alloc netdev!\n", name);
>
> If this is a clean up patch I think this pr_err() could also be removed?
> Memory allocation usually fail very loudly so there should be no reason
> to print more errors.
>

Sure, I just didn't want to alter the behaviour too much.

> > - rtnl_unlock();
> > - return -ENOMEM;
> > + res = -ENOMEM;
> > + goto out_unlock;
> > }
> >
> > /*
> > @@ -4905,14 +4905,17 @@ int bond_create(struct net *net, const char *name)
> > bond_dev->rtnl_link_ops = &bond_link_ops;
> >
> > res = register_netdevice(bond_dev);
> > + if (res < 0) {
> > + free_netdev(bond_dev);
> > + goto out_unlock;
> > + }
> >
> > netif_carrier_off(bond_dev);
> >
> > bond_work_init_all(bond);
> >
> > +out_unlock:
> > rtnl_unlock();
> > - if (res < 0)
> > - free_netdev(bond_dev);
> > return res;
> > }
> >
>
> I do appreciate that the change makes the error handling follow a more
> usual kernel pattern, but IMHO it'd be even better if the error
> handling was completely moved. IOW the success path should end with
> return 0; and the error path should contain free_netdev(bond_dev);
>
> - int res;
> + int err;
>
> [...]
>
> rtnl_unlock();
>
> return 0;
>
> err_free_netdev:
> free_netdev(bond_dev);
> err_unlock:
> rtnl_unlock();
> return err;
>
> I'm just not 100% sold on the improvement made by this patch being
> worth the code churn, please convince me, respin or get an ack from
> one of the maintainers? :)
>

ACK :)

--
Matteo Croce
per aspera ad upstream