[PATCH 4.14 003/122] Revert "OPP: Protect dev_list with opp_table lock"

Greg Kroah-Hartman
2019-11-22T11:16:27Z

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 714ab224a8db6e8255c61a42613de9349ceb0bba which is
commit 3d2556992a878a2210d3be498416aee39e0c32aa upstream.

Turns out to break the build on the odroid machines, so it needs to be
reverted.

Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Cc: Niklas Cassel <niklas.cassel@linaro.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/power/opp/core.c | 21 ++-------------------
drivers/base/power/opp/cpu.c | 2 --
drivers/base/power/opp/opp.h | 2 +-
3 files changed, 3 insertions(+), 22 deletions(-)

--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -49,14 +49,9 @@ static struct opp_device *_find_opp_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) {
- mutex_lock(&opp_table->lock);
- found = !!_find_opp_dev(dev, opp_table);
- mutex_unlock(&opp_table->lock);
-
- if (found) {
+ if (_find_opp_dev(dev, opp_table)) {
_get_opp_table_kref(opp_table);

return opp_table;
@@ -716,8 +711,6 @@ struct opp_device *_add_opp_dev(const st

/* 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 */
@@ -725,7 +718,6 @@ struct opp_device *_add_opp_dev(const st
if (ret)
dev_err(dev, "%s: Failed to register opp debugfs (%d)\n",
__func__, ret);
- mutex_unlock(&opp_table->lock);

return opp_dev;
}
@@ -744,7 +736,6 @@ static struct opp_table *_allocate_opp_t
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);
@@ -766,6 +757,7 @@ static struct opp_table *_allocate_opp_t

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 */
@@ -807,10 +799,6 @@ static void _opp_table_kref_release(stru
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);

@@ -1714,9 +1702,6 @@ void _dev_pm_opp_remove_table(struct opp
{
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 */
@@ -1727,8 +1712,6 @@ void _dev_pm_opp_remove_table(struct opp
} 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)
--- a/drivers/base/power/opp/cpu.c
+++ b/drivers/base/power/opp/cpu.c
@@ -222,10 +222,8 @@ int dev_pm_opp_get_sharing_cpus(struct d
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);
}
--- a/drivers/base/power/opp/opp.h
+++ b/drivers/base/power/opp/opp.h
@@ -124,7 +124,7 @@ 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 and dev_list.
+ * @lock: mutex protecting the opp_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.