Merge remote branch 'anholt/drm-intel-next' into drm-next

* anholt/drm-intel-next: (515 commits)
  drm/i915: Fix out of tree builds
  drm/i915: move fence lru to struct drm_i915_fence_reg
  drm/i915: don't allow tiling changes on pinned buffers v2
  drm/i915: Be extra careful about A/D matching for multifunction SDVO
  drm/i915: Fix DDC bus selection for multifunction SDVO
  drm/i915: cleanup mode setting before unmapping registers
  drm/i915: Make fbc control wrapper functions
  drm/i915: Wait for the GPU whilst shrinking, if truly desperate.
  drm/i915: Use spatio-temporal dithering on PCH
  [MTD] Remove zero-length files mtdbdi.c and internal.ho
  pata_pcmcia / ide-cs: Fix bad hashes for Transcend and kingston IDs
  libata: Fix several inaccuracies in developer's guide
  slub: Fix bad boundary check in init_kmem_cache_nodes()
  raid6: fix recovery performance regression
  KEYS: call_sbin_request_key() must write lock keyrings before modifying them
  KEYS: Use RCU dereference wrappers in keyring key type code
  KEYS: find_keyring_by_name() can gain access to a freed keyring
  ALSA: hda: Fix 0 dB for Packard Bell models using Conexant CX20549 (Venice)
  ALSA: hda - Add quirk for Dell Inspiron 19T using a Conexant CX20582
  ALSA: take tu->qlock with irqs disabled
  ...

1 files changed, 14 insertions, 4 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 6af210a7de70..3c2a54f70ffe 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -323,6 +323,15 @@ static inline struct task_group *task_group(struct task_struct *p)
 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 {
+	/*
+	 * Strictly speaking this rcu_read_lock() is not needed since the
+	 * task_group is tied to the cgroup, which in turn can never go away
+	 * as long as there are tasks attached to it.
+	 *
+	 * However since task_group() uses task_subsys_state() which is an
+	 * rcu_dereference() user, this quiets CONFIG_PROVE_RCU.
+	 */
+	rcu_read_lock();
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
 	p->se.parent = task_group(p)->se[cpu];
@@ -332,6 +341,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 	p->rt.rt_rq  = task_group(p)->rt_rq[cpu];
 	p->rt.parent = task_group(p)->rt_se[cpu];
 #endif
+	rcu_read_unlock();
 }
 
 #else
@@ -3780,7 +3790,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
 	 * the mutex owner just released it and exited.
 	 */
 	if (probe_kernel_address(&owner->cpu, cpu))
-		goto out;
+		return 0;
 #else
 	cpu = owner->cpu;
 #endif
@@ -3790,14 +3800,14 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
 	 * the cpu field may no longer be valid.
 	 */
 	if (cpu >= nr_cpumask_bits)
-		goto out;
+		return 0;
 
 	/*
 	 * We need to validate that we can do a
 	 * get_cpu() and that we have the percpu area.
 	 */
 	if (!cpu_online(cpu))
-		goto out;
+		return 0;
 
 	rq = cpu_rq(cpu);
 
@@ -3816,7 +3826,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
 
 		cpu_relax();
 	}
-out:
+
 	return 1;
 }
 #endif