The dev_list needs to be protected with a lock, else we may have simultaneous access (addition/removal) to it and that would be racy. Extend scope of the opp_table lock to protect dev_list as well.
Signed-off-by: Viresh Kumar <[email protected]> --- drivers/opp/core.c | 21 +++++++++++++++++++-- drivers/opp/cpu.c | 2 ++ drivers/opp/opp.h | 2 +- 3 files changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/opp/core.c b/drivers/opp/core.c index 31ff03dbeb83..9f8aa31265fe 100644 --- a/drivers/opp/core.c +++ b/drivers/opp/core.c @@ -48,9 +48,14 @@ static struct opp_device *_find_opp_dev(const struct device *dev, static struct opp_table *_find_opp_table_unlocked(struct device *dev) { struct opp_table *opp_table; + bool found; list_for_each_entry(opp_table, &opp_tables, node) { - if (_find_opp_dev(dev, opp_table)) { + mutex_lock(&opp_table->lock); + found = !!_find_opp_dev(dev, opp_table); + mutex_unlock(&opp_table->lock); + + if (found) { _get_opp_table_kref(opp_table); return opp_table; @@ -766,6 +771,8 @@ struct opp_device *_add_opp_dev(const struct device *dev, /* Initialize opp-dev */ opp_dev->dev = dev; + + mutex_lock(&opp_table->lock); list_add(&opp_dev->node, &opp_table->dev_list); /* Create debugfs entries for the opp_table */ @@ -773,6 +780,7 @@ struct opp_device *_add_opp_dev(const struct device *dev, if (ret) dev_err(dev, "%s: Failed to register opp debugfs (%d)\n", __func__, ret); + mutex_unlock(&opp_table->lock); return opp_dev; } @@ -791,6 +799,7 @@ static struct opp_table *_allocate_opp_table(struct device *dev) if (!opp_table) return NULL; + mutex_init(&opp_table->lock); INIT_LIST_HEAD(&opp_table->dev_list); opp_dev = _add_opp_dev(dev, opp_table); @@ -812,7 +821,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev) BLOCKING_INIT_NOTIFIER_HEAD(&opp_table->head); INIT_LIST_HEAD(&opp_table->opp_list); - mutex_init(&opp_table->lock); kref_init(&opp_table->kref); /* Secure the device table modification */ @@ -854,6 +862,10 @@ static void _opp_table_kref_release(struct kref *kref) if (!IS_ERR(opp_table->clk)) clk_put(opp_table->clk); + /* + * No need to take opp_table->lock here as we are guaranteed that no + * references to the OPP table are taken at this point. + */ opp_dev = list_first_entry(&opp_table->dev_list, struct opp_device, node); @@ -1716,6 +1728,9 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev, { struct dev_pm_opp *opp, *tmp; + /* Protect dev_list */ + mutex_lock(&opp_table->lock); + /* Find if opp_table manages a single device */ if (list_is_singular(&opp_table->dev_list)) { /* Free static OPPs */ @@ -1733,6 +1748,8 @@ void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev, } else { _remove_opp_dev(_find_opp_dev(dev, opp_table), opp_table); } + + mutex_unlock(&opp_table->lock); } void _dev_pm_opp_find_and_remove_table(struct device *dev, bool remove_all) diff --git a/drivers/opp/cpu.c b/drivers/opp/cpu.c index 0c0910709435..2868a022a040 100644 --- a/drivers/opp/cpu.c +++ b/drivers/opp/cpu.c @@ -222,8 +222,10 @@ int dev_pm_opp_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) cpumask_clear(cpumask); if (opp_table->shared_opp == OPP_TABLE_ACCESS_SHARED) { + mutex_lock(&opp_table->lock); list_for_each_entry(opp_dev, &opp_table->dev_list, node) cpumask_set_cpu(opp_dev->dev->id, cpumask); + mutex_unlock(&opp_table->lock); } else { cpumask_set_cpu(cpu_dev->id, cpumask); } diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h index 7c540fd063b2..e0866b1c1f1b 100644 --- a/drivers/opp/opp.h +++ b/drivers/opp/opp.h @@ -126,7 +126,7 @@ enum opp_table_access { * @dev_list: list of devices that share these OPPs * @opp_list: table of opps * @kref: for reference count of the table. - * @lock: mutex protecting the opp_list. + * @lock: mutex protecting the opp_list and dev_list. * @np: struct device_node pointer for opp's DT node. * @clock_latency_ns_max: Max clock latency in nanoseconds. * @shared_opp: OPP is shared between multiple devices. -- 2.18.0.rc1.242.g61856ae69a2c
