Promotion of kernel.lnx.4.4-161103.

CRs      Change ID                                   Subject
--------------------------------------------------------------------------------------------------------------
1084491   Ia9350b9c7810db7eb900957b4ce5dac046ab5e0d   ARM: dts: msm: Add qcom,dump-size entry for dumping CPU
1084491   I37ca3aae0471fcd60499615df77093d5b5451bf8   Documentation: arm: add cache DT bindings
1078910   I9cb454cebb74df291479cecc3533d2c684363f77   ion: disable system contig heap
1077179   I5bc6a5a46311206818d70567e31fd84adc0128be   leds: qpnp-flash-v2: Fix strobe control settings
1077868   Id568f76e03b93cf411366abf01ea857fb80ff1bf   ARM: dts: msm: correct cpu nodes information for msmtrit
1083761   Ib38ecabb3c4bf40fcf5ad368fbbdbe4c44edbf3b   msm: vidc: Scale bus bw along with venus clocks
1084236   I4c13601b0fded6de9d8f897c6d471c6a40c90e4d   sched/hmp: Automatically add children threads to colocat
1070067   I0d4b9f72a12e91b16f3844ac70db33b7de5e5263   usb_bam: Avoid uninitialized variable errors
1080024   I92bd53432a11241228d2e5ac89a3b20d19b05a31   CHROMIUM: dm: boot time specification of dm=
1049826   I3e11ca7f6df4bb0d928512f81f3e3dc40fed791a   msm: camera: cpp: Validate frame message before manipula
1080024   I952d86fd1475f0825f9be1386e3497b36127abd0   ANDROID: dm: Rebase on top of 4.1
1082476 1750919   I3a79950b76c1c38e487471f21dc60590b032dd3f   msm: vidc: Correct debugfs directory name
1080024   I4ba1043965d25ec444a833283392ac2394c845f3   Revert "init: do_mounts: Add a dummy definition for dm_t
1084009   Ie1a5038458b0b93dfec3e5bfc350686eb1f8eb1b   ASoC: wcd934x: Initialize mbhc pointer before access
1080688   Ia60fc3ecb5c2aba19effe1c8242f2d89fdef3ebd   ARM: dts: msm: specify SPI configuration for msmfalcon.
1083524   Ic26fa36bf84bce020ad07ad87de50e684dd7fa5a   ARM: dts: msm: Add initial support for msmcobalt V2 QRD
1075835 1075868   I06426109ab39d33e2b11514082c0bc989c4c8167   coresight: tmc: avoid null pointer dereference
1072541   If2b3e241076a4e0eeb87eeb4361398313fca6962   dwc3: gadget: Remove disabling events and ep0 from gadge
1081711   Iee908c56ec530569b35dafa060139e0428efc781   soc: qcom: scm: add check to avoid buffer overflow
1025311   Ie432af1fefc79f88ec67d212f8b9880355c4266d   cfg80211: support virtual interfaces with different beac
1043802   I3eb92f83b42b0fa28dc73f6e0d4f74ef50375855   ARM: dts: msm: add support for QBT1000 on msmcobalt
1082843   I6ab3992958a659995b7d5020287fd6e47e28f2a4   clk: msm: clock-debug: Print VDD level in clock_state tr
1082816   I475d1219ae62378a90c69642f2320149d0f13885   ASoc: wcd934x: correct MAD micbias setting
967547   I92b10e62be8129ead5859a285bf964ab0a3ae2fd   driver core: fix race between creating/querying glue dir
1084935   I31e8e0b5e9ae240ca031f625cf7c49f1bfe165d4   msm: secure_buffer: fix scm call argument layout
1074738   Ie7f8cee59b90f16f8a844d618a6f903b3e3c2f27   msm: mdss: lock mutex before setting backlight

Change-Id: Id13d60a1768a89563fa5209fc5fe3abfc2ea7bb0
CRs-Fixed: 1077179, 1075868, 1082476, 1083761, 1081711, 1043802, 1084935, 1049826, 1070067, 1082816, 1025311, 1074738, 1083524, 1075835, 1080024, 1750919, 1072541, 1084491, 1084009, 1077868, 967547, 1084236, 1080688, 1078910, 1082843

2 files changed, 85 insertions, 62 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c07d844c576e..f3b1688b3be7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2572,8 +2572,8 @@ void wake_up_new_task(struct task_struct *p)
 	unsigned long flags;
 	struct rq *rq;
 
-	raw_spin_lock_irqsave(&p->pi_lock, flags);
 	add_new_task_to_grp(p);
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
 	/* Initialize new task's runnable average */
 	init_entity_runnable_average(&p->se);
 #ifdef CONFIG_SMP
diff --git a/kernel/sched/hmp.c b/kernel/sched/hmp.c
index 1d55e226196f..56f4c60d4d5d 100644
--- a/kernel/sched/hmp.c
+++ b/kernel/sched/hmp.c
@@ -1396,16 +1396,6 @@ void reset_hmp_stats(struct hmp_sched_stats *stats, int reset_cra)
 	}
 }
 
-/*
- * Invoked from three places:
- *	1) try_to_wake_up() -> ... -> select_best_cpu()
- *	2) scheduler_tick() -> ... -> migration_needed() -> select_best_cpu()
- *	3) can_migrate_task()
- *
- * Its safe to de-reference p->grp in first case (since p->pi_lock is held)
- * but not in other cases. p->grp is hence freed after a RCU grace period and
- * accessed under rcu_read_lock()
- */
 int preferred_cluster(struct sched_cluster *cluster, struct task_struct *p)
 {
 	struct related_thread_group *grp;
@@ -3883,7 +3873,12 @@ static void _set_preferred_cluster(struct related_thread_group *grp)
 
 void set_preferred_cluster(struct related_thread_group *grp)
 {
-	raw_spin_lock(&grp->lock);
+	/*
+	 * Prevent possible deadlock with update_children(). Not updating
+	 * the preferred cluster once is not a big deal.
+	 */
+	if (!raw_spin_trylock(&grp->lock))
+		return;
 	_set_preferred_cluster(grp);
 	raw_spin_unlock(&grp->lock);
 }
@@ -3904,7 +3899,7 @@ static int alloc_group_cputime(struct related_thread_group *grp)
 	struct rq *rq = cpu_rq(cpu);
 	u64 window_start = rq->window_start;
 
-	grp->cpu_time = alloc_percpu(struct group_cpu_time);
+	grp->cpu_time = alloc_percpu_gfp(struct group_cpu_time, GFP_ATOMIC);
 	if (!grp->cpu_time)
 		return -ENOMEM;
 
@@ -4088,7 +4083,7 @@ struct related_thread_group *alloc_related_thread_group(int group_id)
 {
 	struct related_thread_group *grp;
 
-	grp = kzalloc(sizeof(*grp), GFP_KERNEL);
+	grp = kzalloc(sizeof(*grp), GFP_ATOMIC);
 	if (!grp)
 		return ERR_PTR(-ENOMEM);
 
@@ -4127,19 +4122,64 @@ static void free_related_thread_group(struct rcu_head *rcu)
 	kfree(grp);
 }
 
+/*
+ * The thread group for a task can change while we are here. However,
+ * add_new_task_to_grp() will take care of any tasks that we miss here.
+ * When a parent exits, and a child thread is simultaneously exiting,
+ * sched_set_group_id() will synchronize those operations.
+ */
+static void update_children(struct task_struct *leader,
+			struct related_thread_group *grp, int event)
+{
+	struct task_struct *child;
+	struct rq *rq;
+	unsigned long flags;
+
+	if (!thread_group_leader(leader))
+		return;
+
+	if (event == ADD_TASK && !sysctl_sched_enable_thread_grouping)
+		return;
+
+	if (thread_group_empty(leader))
+		return;
+
+	child = next_thread(leader);
+
+	do {
+		rq = task_rq_lock(child, &flags);
+
+		if (event == REM_TASK && child->grp && grp == child->grp) {
+			transfer_busy_time(rq, grp, child, event);
+			list_del_init(&child->grp_list);
+			rcu_assign_pointer(child->grp, NULL);
+		} else if (event == ADD_TASK && !child->grp) {
+			transfer_busy_time(rq, grp, child, event);
+			list_add(&child->grp_list, &grp->tasks);
+			rcu_assign_pointer(child->grp, grp);
+		}
+
+		task_rq_unlock(rq, child, &flags);
+	}  while_each_thread(leader, child);
+
+}
+
 static void remove_task_from_group(struct task_struct *p)
 {
 	struct related_thread_group *grp = p->grp;
 	struct rq *rq;
 	int empty_group = 1;
+	unsigned long flags;
 
 	raw_spin_lock(&grp->lock);
 
-	rq = __task_rq_lock(p);
+	rq = task_rq_lock(p, &flags);
 	transfer_busy_time(rq, p->grp, p, REM_TASK);
 	list_del_init(&p->grp_list);
 	rcu_assign_pointer(p->grp, NULL);
-	__task_rq_unlock(rq);
+	task_rq_unlock(rq, p, &flags);
+
+	update_children(p, grp, REM_TASK);
 
 	if (!list_empty(&grp->tasks)) {
 		empty_group = 0;
@@ -4158,6 +4198,7 @@ static int
 add_task_to_group(struct task_struct *p, struct related_thread_group *grp)
 {
 	struct rq *rq;
+	unsigned long flags;
 
 	raw_spin_lock(&grp->lock);
 
@@ -4165,11 +4206,13 @@ add_task_to_group(struct task_struct *p, struct related_thread_group *grp)
 	 * Change p->grp under rq->lock. Will prevent races with read-side
 	 * reference of p->grp in various hot-paths
 	 */
-	rq = __task_rq_lock(p);
+	rq = task_rq_lock(p, &flags);
 	transfer_busy_time(rq, grp, p, ADD_TASK);
 	list_add(&p->grp_list, &grp->tasks);
 	rcu_assign_pointer(p->grp, grp);
-	__task_rq_unlock(rq);
+	task_rq_unlock(rq, p, &flags);
+
+	update_children(p, grp, ADD_TASK);
 
 	_set_preferred_cluster(grp);
 
@@ -4192,82 +4235,62 @@ void add_new_task_to_grp(struct task_struct *new)
 
 	parent = new->group_leader;
 
-	/*
-	 * The parent's pi_lock is required here to protect race
-	 * against the parent task being removed from the
-	 * group.
-	 */
-	raw_spin_lock_irqsave(&parent->pi_lock, flags);
+	write_lock_irqsave(&related_thread_group_lock, flags);
 
-	/* protected by pi_lock. */
+	rcu_read_lock();
 	grp = task_related_thread_group(parent);
-	if (!grp) {
-		raw_spin_unlock_irqrestore(&parent->pi_lock, flags);
+	rcu_read_unlock();
+
+	/* Its possible that update_children() already added us to the group */
+	if (!grp || new->grp) {
+		write_unlock_irqrestore(&related_thread_group_lock, flags);
 		return;
 	}
+
 	raw_spin_lock(&grp->lock);
 
 	rcu_assign_pointer(new->grp, grp);
 	list_add(&new->grp_list, &grp->tasks);
 
 	raw_spin_unlock(&grp->lock);
-	raw_spin_unlock_irqrestore(&parent->pi_lock, flags);
+	write_unlock_irqrestore(&related_thread_group_lock, flags);
 }
 
 int sched_set_group_id(struct task_struct *p, unsigned int group_id)
 {
-	int rc = 0, destroy = 0;
+	int rc = 0;
 	unsigned long flags;
-	struct related_thread_group *grp = NULL, *new = NULL;
+	struct related_thread_group *grp = NULL;
 
-redo:
-	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	/* Prevents tasks from exiting while we are managing groups. */
+	write_lock_irqsave(&related_thread_group_lock, flags);
 
+	/* Switching from one group to another directly is not permitted */
 	if ((current != p && p->flags & PF_EXITING) ||
 			(!p->grp && !group_id) ||
-			(p->grp && p->grp->id == group_id))
+			(p->grp && group_id))
 		goto done;
 
-	write_lock(&related_thread_group_lock);
-
 	if (!group_id) {
 		remove_task_from_group(p);
-		write_unlock(&related_thread_group_lock);
 		goto done;
 	}
 
-	if (p->grp && p->grp->id != group_id)
-		remove_task_from_group(p);
-
 	grp = lookup_related_thread_group(group_id);
-	if (!grp && !new) {
-		/* New group */
-		write_unlock(&related_thread_group_lock);
-		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
-		new = alloc_related_thread_group(group_id);
-		if (IS_ERR(new))
-			return -ENOMEM;
-		destroy = 1;
-		/* Rerun checks (like task exiting), since we dropped pi_lock */
-		goto redo;
-	} else if (!grp && new) {
-		/* New group - use object allocated before */
-		destroy = 0;
-		list_add(&new->list, &related_thread_groups);
-		grp = new;
+	if (!grp) {
+		grp = alloc_related_thread_group(group_id);
+		if (IS_ERR(grp)) {
+			rc = -ENOMEM;
+			goto done;
+		}
+
+		list_add(&grp->list, &related_thread_groups);
 	}
 
 	BUG_ON(!grp);
 	rc = add_task_to_group(p, grp);
-	write_unlock(&related_thread_group_lock);
 done:
-	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
-
-	if (new && destroy) {
-		free_group_cputime(new);
-		kfree(new);
-	}
-
+	write_unlock_irqrestore(&related_thread_group_lock, flags);
 	return rc;
 }