On Thu, Oct 12, 2017 at 06:56:29PM -0700, Keith Packard wrote:
> This provides new data structures to hold "lease" information about
> drm mode setting objects, and provides for creating new drm_masters
> which have access to a subset of the available drm resources.
>
> An 'owner' is a drm_master which is not leasing the objects from
> another drm_master, and hence 'owns' them.
>
> A 'lessee' is a drm_master which is leasing objects from some other
> drm_master. Each lessee holds the set of objects which it is leasing
> from the lessor.
>
> A 'lessor' is a drm_master which is leasing objects to another
> drm_master. This is the same as the owner in the current code.
>
> The set of objects any drm_master 'controls' is limited to the set of
> objects it leases (for lessees) or all objects (for owners).
>
> Objects not controlled by a drm_master cannot be modified through the
> various state manipulating ioctls, and any state reported back to user
> space will be edited to make them appear idle and/or unusable. For
> instance, connectors always report 'disconnected', while encoders
> report no possible crtcs or clones.
>
> The full list of lessees leasing objects from an owner (either
> directly, or indirectly through another lessee), can be searched from
> an idr in the drm_master of the owner.
>
> Changes for v2 as suggested by Daniel Vetter <daniel.vetter@xxxxxxxx>:
>
> * Sub-leasing has been disabled.
>
> * BUG_ON for lock checking replaced with lockdep_assert_held
>
> * 'change' ioctl has been removed.
>
> * Leased objects can always be controlled by the lessor; the
> 'mask_lease' flag has been removed
>
> * Checking for leased status has been simplified, replacing
> the drm_lease_check function with drm_lease_held.
>
> Changes in v3, some suggested by Dave Airlie <airlied@xxxxxxxxx>
>
> * Add revocation. This allows leases to be effectively revoked by
> removing all of the objects they have access to. The lease itself
> hangs around as it's hanging off a file.
>
> * Free the leases IDR when the master is destroyed
>
> * _drm_lease_held should look at lessees, not lessor
>
> * Allow non-master files to check for lease status
>
> Changes in v4, suggested by Dave Airlie <airlied@xxxxxxxxx>
>
> * Formatting and whitespace changes
>
> Signed-off-by: Keith Packard <keithp@xxxxxxxxxx>
> ---
> drivers/gpu/drm/Makefile | 2 +-
> drivers/gpu/drm/drm_auth.c | 29 +++-
> drivers/gpu/drm/drm_lease.c | 339 ++++++++++++++++++++++++++++++++++++++++++
> include/drm/drm_auth.h | 20 +++
> include/drm/drm_lease.h | 36 +++++
> include/drm/drm_mode_object.h | 1 +
> 6 files changed, 425 insertions(+), 2 deletions(-)
> create mode 100644 drivers/gpu/drm/drm_lease.c
> create mode 100644 include/drm/drm_lease.h
>
<snip />
> diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
> new file mode 100644
> index 000000000000..6c3f2445254c
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_lease.c
<snip />
> +
> +/**
> + * _drm_lease_revoke - revoke access to all leased objects
Can you add "(idr_mutex held)" like you have in _drm_lease_held()?
> + * @master: the master losing its lease
s/master/top/
> + */
> +
> +void _drm_lease_revoke(struct drm_master *top)
> +{
> + int object;
> + void *entry;
> + struct drm_master *master = top;
> +
lockdep_assert_held(&top->dev->mode_config.idr_mutex);
With these nits fixed,
Reviewed-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
> + /*
> + * Walk the tree starting at 'top' emptying all leases. Because
> + * the tree is fully connected, we can do this without recursing
> + */
> + for (;;) {
> + DRM_DEBUG_LEASE("revoke leases for %p %d\n", master, master->lessee_id);
> +
> + /* Evacuate the lease */
> + idr_for_each_entry(&master->leases, entry, object)
> + idr_remove(&master->leases, object);
> +
> + /* Depth-first list walk */
> +
> + /* Down */
> + if (!list_empty(&master->lessees)) {
> + master = list_first_entry(&master->lessees, struct drm_master, lessee_list);
> + } else {
> + /* Up */
> + while (master != top && master == list_last_entry(&master->lessor->lessees, struct drm_master, lessee_list))
> + master = master->lessor;
> +
> + if (master == top)
> + break;
> +
> + /* Over */
> + master = list_entry(master->lessee_list.next, struct drm_master, lessee_list);
> + }
> + }
> +}
<snip />
> --
> 2.15.0.rc0
>
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--
Sean Paul, Software Engineer, Google / Chromium OS
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