On Fri, 1 Dec 2017 14:43:06 +0100, Phil Sutter wrote:
> On Thu, Nov 30, 2017 at 05:35:39PM -0800, Jakub Kicinski wrote:
> [...]
> > +static int nsim_vfs_enable(struct netdevsim *ns, unsigned int num_vfs)
> > +{
> > + ns->vfconfigs = kcalloc(num_vfs, sizeof(struct nsim_vf_config),
> > + GFP_KERNEL);
> > + if (!ns->vfconfigs)
> > + return -ENOMEM;
> > + ns->num_vfs = num_vfs;
> > +
> > + return 0;
> > +}
> > +
> > +static void nsim_vfs_disable(struct netdevsim *ns)
> > +{
> > + kfree(ns->vfconfigs);
> > + ns->vfconfigs = NULL;
> > + ns->num_vfs = 0;
> > +}
>
> Why not something like:
>
> | static int nsim_vfs_set(struct netdevsim *ns, unsigned int num_vfs)
> | {
> | void *ptr = krealloc(ns->vfconfigs,
> | num_vfs * sizeof(struct nsim_vf_config),
> | GFP_KERNEL);
> |
> | if (!ptr)
> | return -ENOMEM;
> |
> | ns->vfconfigs = ptr;
> | ns->num_vfs = num_vfs;
> | return 0;
> | }
Um. It either frees or allocates, never reallocates so I felt realloc
is misleading. ZERO_SIZE_PTR is less clearly a NULL than a NULL. I
will have to specify __GFP_ZERO. It's not a calloc so there could be
potentially some overflows?
> > +static ssize_t
> > +nsim_numvfs_store(struct device *dev, struct device_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct netdevsim *ns = to_nsim(dev);
> > + unsigned int num_vfs;
> > + int ret;
> > +
> > + ret = kstrtouint(buf, 0, &num_vfs);
> > + if (ret)
> > + return ret;
> > +
> > + rtnl_lock();
> > + if (ns->num_vfs == num_vfs)
> > + goto exit_good;
>
> Then replace this:
>
> > + if (ns->num_vfs && num_vfs) {
> > + ret = -EBUSY;
> > + goto exit_unlock;
> > + }
> > +
> > + if (num_vfs) {
> > + ret = nsim_vfs_enable(ns, num_vfs);
> > + if (ret)
> > + goto exit_unlock;
> > + } else {
> > + nsim_vfs_disable(ns);
> > + }
>
> with just:
>
> | nsim_vfs_set(ns, num_vfs);
I'm trying to mirror the PCI subsystem behaviour here, which only
allows enable or disable, not increase. I felt we should follow how
real devices behave:
/* enable VFs */
if (pdev->sriov->num_VFs) {
dev_warn(&pdev->dev, "%d VFs already enabled. Disable before
enabling %d VFs\n",
pdev->sriov->num_VFs, num_vfs);
return -EBUSY;
}
So IOW this is intentional.
> > + ret = count;
> > +exit_unlock:
> > + rtnl_unlock();
> > +
> > + return ret;
> > +}
>
> [...]
>
> > +static void nsim_free(struct net_device *dev)
> > +{
> > + struct netdevsim *ns = netdev_priv(dev);
> > +
> > + device_unregister(&ns->dev);
> > }
>
> Shouldn't this also kfree(ns->vfconfigs)?
It's in uninit, I will move it to release.
