Hello,
On Thu, Feb 01, 2018 at 11:53:09AM -0800, Matt Roper wrote:
> * Drivers may be built as modules (and unloaded/reloaded) which is not
> something cgroup controllers support today.
As discussed in the other subthread, this shouldn't be a concern.
> * Drivers may wish to provide their own interface to allow userspace to
> adjust driver-specific settings (e.g., via a driver ioctl rather than
> via the kernfs filesystem).
> * A single driver may be managing multiple devices and wish to maintain
> different driver-specific cgroup data for each.
If you look at io and rdma controllers, they already do this.
> Note that technically these interfaces aren't restricted to drivers
> (other non-driver parts of the kernel could make use of them as well).
> I expect drivers to be the primary consumers of this interface and
> couldn't think of a more appropriate generic name (the term "subsystem"
> would probably be more accurate, but that's already used by cgroup
> controllers).
Let's please not do "driver", it's really confusing. Just coming up
with a made-up word would be fine as long as the connection can be
made and the word is easily identifiable. e.g. cgroup cdata / pdata for
cgroup custom / priv data.
> +/*
> + * Driver-specific cgroup data. Drivers should subclass this structure with
> + * their own fields for data that should be stored alongside individual
> + * cgroups.
> + */
> +struct cgroup_driver_data {
> + /* Driver this data structure is associated with */
> + struct cgroup_driver *drv;
> +
> + /* Node in cgroup's data hashtable */
> + struct hlist_node cgroupnode;
> +
> + /* Node in driver's data list; used to cleanup on driver unload */
> + struct list_head drivernode;
> +};
...
> +struct cgroup_driver {
> + /* Functions this driver uses to manage its data */
> + struct cgroup_driver_funcs *funcs;
> +
> + /*
> + * List of driver-specific data structures that need to be cleaned up
> + * if driver is unloaded.
> + */
> + struct list_head datalist;
> +};
It generally looks great but can we do something like the following in
terms of interface?
struct cgroup_cdata {
const void *key;
void (*free)(struct cgroup_cdata *cdata);
/* whatever other necessary fields */
char data[];
};
int cgroup_cdata_install(struct cgroup *cgrp, struct cgroup_cdata *cdata);
struct cgroup_cdata *cgroup_cdata_lookup(struct cgroup *cgrp, const void *key);
int cgroup_cdata_free(struct cgroup *cgrp, const void *key);
/* free is also automatically called when the cgroup is released */
And please use a separate lock or mutex for managing them.
Thanks.
--
tejun
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