drm: make DRM_UNLOCKED ioctls with their own mutex
drm_getclient, drm_getstats and drm_getmap (with a few minor
adjustments) do not need global mutex, so fix that and
make the said ioctls DRM_UNLOCKED. Details:
drm_getclient: the only thing that should be protected here
is dev->filelist and that is already protected everywhere with
dev->struct_mutex.
drm_getstats: there is no need for any mutex here because the
loop runs through quasi-static (set at load time only)
data, and the actual count access is done with atomic_read()
drm_getmap already uses dev->struct_mutex to protect
dev->maplist, which also used to protect the same structure
everywhere else except at three places:
* drm_getsarea, which doesn't grab *any* mutex before
touching dev->maplist (so no drm_global_mutex doesn't help
here either; different issue for a different patch).
However, drivers seem to call it only at
initialization time so it probably doesn't matter
* drm_master_destroy, which is called from drm_master_put,
which in turn is protected with dev->struct_mutex
everywhere else in drm module, so we are good here too.
* drm_getsareactx, which releases the dev->struct_mutex
too early, but this patch includes the fix for that.
v2: * incorporate comments received from Daniel Vetter
* include the (long) explanation above to make it clear what
we are doing (and why), also at Daniel Vetter's request
* tighten up mutex grab/release locations to only
encompass real critical sections, rather than some
random code around them
Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_context.c b/drivers/gpu/drm/drm_context.c
index 6d440fb..325365f 100644
--- a/drivers/gpu/drm/drm_context.c
+++ b/drivers/gpu/drm/drm_context.c
@@ -154,8 +154,6 @@
return -EINVAL;
}
- mutex_unlock(&dev->struct_mutex);
-
request->handle = NULL;
list_for_each_entry(_entry, &dev->maplist, head) {
if (_entry->map == map) {
@@ -164,6 +162,9 @@
break;
}
}
+
+ mutex_unlock(&dev->struct_mutex);
+
if (request->handle == NULL)
return -EINVAL;
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 1919ef0..ebf7d3f 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -65,9 +65,9 @@
DRM_IOCTL_DEF(DRM_IOCTL_GET_UNIQUE, drm_getunique, 0),
DRM_IOCTL_DEF(DRM_IOCTL_GET_MAGIC, drm_getmagic, 0),
DRM_IOCTL_DEF(DRM_IOCTL_IRQ_BUSID, drm_irq_by_busid, DRM_MASTER|DRM_ROOT_ONLY),
- DRM_IOCTL_DEF(DRM_IOCTL_GET_MAP, drm_getmap, 0),
- DRM_IOCTL_DEF(DRM_IOCTL_GET_CLIENT, drm_getclient, 0),
- DRM_IOCTL_DEF(DRM_IOCTL_GET_STATS, drm_getstats, 0),
+ DRM_IOCTL_DEF(DRM_IOCTL_GET_MAP, drm_getmap, DRM_UNLOCKED),
+ DRM_IOCTL_DEF(DRM_IOCTL_GET_CLIENT, drm_getclient, DRM_UNLOCKED),
+ DRM_IOCTL_DEF(DRM_IOCTL_GET_STATS, drm_getstats, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_GET_CAP, drm_getcap, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_SET_VERSION, drm_setversion, DRM_MASTER),
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 904d7e9..956fd38 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -158,14 +158,11 @@
int i;
idx = map->offset;
-
- mutex_lock(&dev->struct_mutex);
- if (idx < 0) {
- mutex_unlock(&dev->struct_mutex);
+ if (idx < 0)
return -EINVAL;
- }
i = 0;
+ mutex_lock(&dev->struct_mutex);
list_for_each(list, &dev->maplist) {
if (i == idx) {
r_list = list_entry(list, struct drm_map_list, head);
@@ -211,9 +208,9 @@
int i;
idx = client->idx;
- mutex_lock(&dev->struct_mutex);
-
i = 0;
+
+ mutex_lock(&dev->struct_mutex);
list_for_each_entry(pt, &dev->filelist, lhead) {
if (i++ >= idx) {
client->auth = pt->authenticated;
@@ -249,8 +246,6 @@
memset(stats, 0, sizeof(*stats));
- mutex_lock(&dev->struct_mutex);
-
for (i = 0; i < dev->counters; i++) {
if (dev->types[i] == _DRM_STAT_LOCK)
stats->data[i].value =
@@ -262,8 +257,6 @@
stats->count = dev->counters;
- mutex_unlock(&dev->struct_mutex);
-
return 0;
}