[PATCH 5.4 001/102] drm/i915: Fix pid leak with banned clients

[Greg Kroah-Hartman]

From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>

commit f0f3a6cecf3b98990985cd42f7bf5a0313894822 upstream.

Get_pid_task() needs to be paired with a put_pid or we leak a pid
reference every time a banned client tries to create a context.

v2:
 * task_pid_nr helper exists! (Chris)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Fixes: b083a0870c79 ("drm/i915: Add per client max context ban limit")
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217170933.8108-1-tvrtko.ursulin@xxxxxxxxxxxxxxx
(cherry picked from commit ba16a48af797db124ac100417f9229b1650ce1fb)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/i915/gem/i915_gem_context.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -2094,8 +2094,7 @@ int i915_gem_context_create_ioctl(struct
 	ext_data.fpriv = file->driver_priv;
 	if (client_is_banned(ext_data.fpriv)) {
 		DRM_DEBUG("client %s[%d] banned from creating ctx\n",
-			  current->comm,
-			  pid_nr(get_task_pid(current, PIDTYPE_PID)));
+			  current->comm, task_pid_nr(current));
 		return -EIO;
 	}