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Commit 7f13d925 authored by Maulik Shah's avatar Maulik Shah
Browse files

cpuidle: lpm-levels: Remove the BUG_ON in get_cluster_sleep_time 



BUG_ON in get_cluster_sleep_time may lead to false alarm when
cluster_unprepare races with cluster_select. The below is the race.

If any core is about to select cci low power mode, it is
possible that another core from same cluster can wakeup and clears
the first cpu mask as well in cci cluster which will lead to crash.

But this is false alarm, since it still has channce to auto correct
the state machine in cluster_configure.

Also rename variable name to num_children_in_sync.

Change-Id: I730e916098dfcfde2c58eab088c84675b2b12172
Signed-off-by: default avatarAnji Jonnala <anjir@codeaurora.org>
Signed-off-by: default avatarMaulik Shah <mkshah@codeaurora.org>
parent 56ec8583

drivers/cpuidle/lpm-levels.c

+21 −20
Original line number Diff line number Diff line
@@ -386,8 +386,8 @@ static uint64_t get_cluster_sleep_time(struct lpm_cluster *cluster, 
			return USEC_PER_SEC * msm_pm_sleep_time_override;

	}



	BUG_ON(!cpumask_and(&online_cpus_in_cluster,

			&cluster->num_childs_in_sync, cpu_online_mask));

	cpumask_and(&online_cpus_in_cluster,

			&cluster->num_children_in_sync, cpu_online_mask);



	for_each_cpu(cpu, &online_cpus_in_cluster) {

		td = &per_cpu(tick_cpu_device, cpu);
@@ -448,7 +448,7 @@ static int cluster_select(struct lpm_cluster *cluster, bool from_idle) 
			cpumask_weight(cpu_online_mask) > 1)

			continue;



		if (!cpumask_equal(&cluster->num_childs_in_sync,

		if (!cpumask_equal(&cluster->num_children_in_sync,

					&level->num_cpu_votes))

			continue;
@@ -490,18 +490,18 @@ static int cluster_configure(struct lpm_cluster *cluster, int idx, 


	spin_lock(&cluster->sync_lock);



	if (!cpumask_equal(&cluster->num_childs_in_sync, &cluster->child_cpus)

			|| is_IPI_pending(&cluster->num_childs_in_sync)) {

	if (!cpumask_equal(&cluster->num_children_in_sync, &cluster->child_cpus)

			|| is_IPI_pending(&cluster->num_children_in_sync)) {

		spin_unlock(&cluster->sync_lock);

		return -EPERM;

	}



	if (idx != cluster->default_level) {

		update_debug_pc_event(CLUSTER_ENTER, idx,

			cluster->num_childs_in_sync.bits[0],

			cluster->num_children_in_sync.bits[0],

			cluster->child_cpus.bits[0], from_idle);

		trace_cluster_enter(cluster->cluster_name, idx,

			cluster->num_childs_in_sync.bits[0],

			cluster->num_children_in_sync.bits[0],

			cluster->child_cpus.bits[0], from_idle);

		lpm_stats_cluster_enter(cluster->stats, idx);

	}
@@ -567,8 +567,8 @@ static void cluster_prepare(struct lpm_cluster *cluster, 
		return;



	spin_lock(&cluster->sync_lock);

	cpumask_or(&cluster->num_childs_in_sync, cpu,

			&cluster->num_childs_in_sync);

	cpumask_or(&cluster->num_children_in_sync, cpu,

			&cluster->num_children_in_sync);



	for (i = 0; i < cluster->nlevels; i++) {

		struct lpm_cluster_level *lvl = &cluster->levels[i];
@@ -585,7 +585,7 @@ static void cluster_prepare(struct lpm_cluster *cluster, 
	 * configuration process

	 */



	if (!cpumask_equal(&cluster->num_childs_in_sync,

	if (!cpumask_equal(&cluster->num_children_in_sync,

				&cluster->child_cpus)) {

		spin_unlock(&cluster->sync_lock);

		return;
@@ -600,7 +600,7 @@ static void cluster_prepare(struct lpm_cluster *cluster, 
	if (cluster_configure(cluster, i, from_idle))

		return;



	cluster_prepare(cluster->parent, &cluster->num_childs_in_sync, i,

	cluster_prepare(cluster->parent, &cluster->num_children_in_sync, i,

			from_idle);

}
@@ -619,10 +619,10 @@ static void cluster_unprepare(struct lpm_cluster *cluster, 


	spin_lock(&cluster->sync_lock);

	last_level = cluster->default_level;

	first_cpu = cpumask_equal(&cluster->num_childs_in_sync,

	first_cpu = cpumask_equal(&cluster->num_children_in_sync,

				&cluster->child_cpus);

	cpumask_andnot(&cluster->num_childs_in_sync,

			&cluster->num_childs_in_sync, cpu);

	cpumask_andnot(&cluster->num_children_in_sync,

			&cluster->num_children_in_sync, cpu);



	for (i = 0; i < cluster->nlevels; i++) {

		struct lpm_cluster_level *lvl = &cluster->levels[i];
@@ -651,10 +651,10 @@ static void cluster_unprepare(struct lpm_cluster *cluster, 
	}



	update_debug_pc_event(CLUSTER_EXIT, cluster->last_level,

			cluster->num_childs_in_sync.bits[0],

			cluster->num_children_in_sync.bits[0],

			cluster->child_cpus.bits[0], from_idle);

	trace_cluster_exit(cluster->cluster_name, cluster->last_level,

			cluster->num_childs_in_sync.bits[0],

			cluster->num_children_in_sync.bits[0],

			cluster->child_cpus.bits[0], from_idle);



	last_level = cluster->last_level;
@@ -733,7 +733,7 @@ int get_cluster_id(struct lpm_cluster *cluster, int *aff_lvl) 


	spin_lock(&cluster->sync_lock);



	if (!cpumask_equal(&cluster->num_childs_in_sync,

	if (!cpumask_equal(&cluster->num_children_in_sync,

				&cluster->child_cpus))

		goto unlock_and_return;
@@ -938,10 +938,10 @@ static int cluster_cpuidle_register(struct lpm_cluster *cl) 
		while (p) {

			int j;

			spin_lock(&p->sync_lock);

			cpumask_set_cpu(cpu, &p->num_childs_in_sync);

			cpumask_set_cpu(cpu, &p->num_children_in_sync);

			for (j = 0; j < p->nlevels; j++)

				cpumask_copy(&p->levels[j].num_cpu_votes,

						&p->num_childs_in_sync);

						&p->num_children_in_sync);

			spin_unlock(&p->sync_lock);

			p = p->parent;

		}
@@ -1198,7 +1198,8 @@ enum msm_pm_l2_scm_flag lpm_cpu_pre_pc_cb(unsigned int cpu) 
		goto unlock_and_return;

	}



	if (!cpumask_equal(&cluster->num_childs_in_sync, &cluster->child_cpus))

	if (!cpumask_equal(&cluster->num_children_in_sync,

						&cluster->child_cpus))

		goto unlock_and_return;



	if (cluster->lpm_dev)

drivers/cpuidle/lpm-levels.h

+1 −1
Original line number Diff line number Diff line
@@ -93,7 +93,7 @@ struct lpm_cluster { 
	struct cpuidle_driver *drv;

	spinlock_t sync_lock;

	struct cpumask child_cpus;

	struct cpumask num_childs_in_sync;

	struct cpumask num_children_in_sync;

	struct lpm_cluster *parent;

	struct lpm_stats *stats;

	unsigned int psci_mode_shift;