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drm: Move master pointer from drm_minor to drm_device

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There can only be one current master, and it's for the overall device.
Render/control minors don't support master-based auth at all.

This simplifies the master logic a lot, at least in my eyes: All these
additional pointer chases are just confusing.

While doing the conversion I spotted some locking fail:
- drm_lock/drm_auth check dev->master without holding the
  master_mutex. This is fallout from

  commit c996fd0b95
  Author: Thomas Hellstrom <thellstrom@vmware.com>
  Date:   Tue Feb 25 19:57:44 2014 +0100

      drm: Protect the master management with a drm_device::master_mutex v3

  but I honestly don't care one bit about those old legacy drivers
  using this.

- debugfs name info should just grab master_mutex.

- And the fbdev helper looked at it to figure out whether someone is
  using KMS. We just need a consistent value, so READ_ONCE. Aside: We
  should probably check if anyone has opened a control node too, but I
  guess current userspace doesn't really do that yet.

v2: Balance locking, reported by Julia.

v3: Rebase on top of Chris' oops fixes.

Cc: Julia Lawall <julia.lawall@lip6.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v2)
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com> (v2)
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1466499262-18717-1-git-send-email-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter
2016-06-21 10:54:12 +02:00
parent 84601dbdea
commit 95c081c17f
8 changed files with 34 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/gpu/drm/drm_bufs.c
View File

@@ -51,7 +51,7 @@ static struct drm_map_list *drm_find_matching_map(struct drm_device *dev,
*/
if (!entry->map ||
map->type != entry->map->type ||
entry->master != dev->primary->master)
entry->master != dev->master)
continue;
switch (map->type) {
case _DRM_SHM:
@@ -245,12 +245,12 @@ static int drm_addmap_core(struct drm_device * dev, resource_size_t offset,
map->offset = (unsigned long)map->handle;
if (map->flags & _DRM_CONTAINS_LOCK) {
/* Prevent a 2nd X Server from creating a 2nd lock */
if (dev->primary->master->lock.hw_lock != NULL) {
if (dev->master->lock.hw_lock != NULL) {
vfree(map->handle);
kfree(map);
return -EBUSY;
}
dev->sigdata.lock = dev->primary->master->lock.hw_lock = map->handle; /* Pointer to lock */
dev->sigdata.lock = dev->master->lock.hw_lock = map->handle; /* Pointer to lock */
}
break;
case _DRM_AGP: {
@@ -356,7 +356,7 @@ static int drm_addmap_core(struct drm_device * dev, resource_size_t offset,
mutex_unlock(&dev->struct_mutex);
if (!(map->flags & _DRM_DRIVER))
list->master = dev->primary->master;
list->master = dev->master;
*maplist = list;
return 0;
}