The OPP structures are abused to the best here, without understanding how the OPP core and RCU locks work.

In short, the OPP pointer saved 'struct exynos_bus' can become invalid under your nose, as the OPP core may free it.

Fix various abuses around OPP structures and calls.

Compile tested only.

Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- I would like it to go via the PM tree. Perhaps that's already the default tree for this.

drivers/devfreq/exynos-bus.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c index 29866f7e6d7e..a8ed7792ece2 100644 --- a/drivers/devfreq/exynos-bus.c +++ b/drivers/devfreq/exynos-bus.c @@ -35,7 +35,7 @@ struct exynos_bus { unsigned int edev_count; struct mutex lock;

- struct dev_pm_opp *curr_opp; + unsigned long curr_freq;

struct regulator *regulator; struct clk *clk; @@ -99,7 +99,7 @@ static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags) { struct exynos_bus *bus = dev_get_drvdata(dev); struct dev_pm_opp *new_opp; - unsigned long old_freq, new_freq, old_volt, new_volt, tol; + unsigned long old_freq, new_freq, new_volt, tol; int ret = 0;

/* Get new opp-bus instance according to new bus clock */ @@ -113,8 +113,7 @@ static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)

new_freq = dev_pm_opp_get_freq(new_opp); new_volt = dev_pm_opp_get_voltage(new_opp); - old_freq = dev_pm_opp_get_freq(bus->curr_opp); - old_volt = dev_pm_opp_get_voltage(bus->curr_opp); + old_freq = bus->curr_freq; rcu_read_unlock();

if (old_freq == new_freq) @@ -146,7 +145,7 @@ static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags) goto out; } } - bus->curr_opp = new_opp; + bus->curr_freq = new_freq;

dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\n", old_freq/1000, new_freq/1000); @@ -163,9 +162,7 @@ static int exynos_bus_get_dev_status(struct device *dev, struct devfreq_event_data edata; int ret;

- rcu_read_lock(); - stat->current_frequency = dev_pm_opp_get_freq(bus->curr_opp); - rcu_read_unlock(); + stat->current_frequency = bus->curr_freq;

ret = exynos_bus_get_event(bus, &edata); if (ret < 0) { @@ -226,7 +223,7 @@ static int exynos_bus_passive_target(struct device *dev, unsigned long *freq, }

new_freq = dev_pm_opp_get_freq(new_opp); - old_freq = dev_pm_opp_get_freq(bus->curr_opp); + old_freq = bus->curr_freq; rcu_read_unlock();

if (old_freq == new_freq) @@ -242,7 +239,7 @@ static int exynos_bus_passive_target(struct device *dev, unsigned long *freq, }

*freq = new_freq; - bus->curr_opp = new_opp; + bus->curr_freq = new_freq;

dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\n", old_freq/1000, new_freq/1000); @@ -335,6 +332,7 @@ static int exynos_bus_parse_of(struct device_node *np, struct exynos_bus *bus) { struct device *dev = bus->dev; + struct dev_pm_opp *opp; unsigned long rate; int ret;

@@ -352,22 +350,23 @@ static int exynos_bus_parse_of(struct device_node *np, }

/* Get the freq and voltage from OPP table to scale the bus freq */ - rcu_read_lock(); ret = dev_pm_opp_of_add_table(dev); if (ret < 0) { dev_err(dev, "failed to get OPP table\n"); - rcu_read_unlock(); goto err_clk; }

rate = clk_get_rate(bus->clk); - bus->curr_opp = devfreq_recommended_opp(dev, &rate, 0); - if (IS_ERR(bus->curr_opp)) { + + rcu_read_lock(); + opp = devfreq_recommended_opp(dev, &rate, 0); + if (IS_ERR(opp)) { dev_err(dev, "failed to find dev_pm_opp\n"); rcu_read_unlock(); - ret = PTR_ERR(bus->curr_opp); + ret = PTR_ERR(opp); goto err_opp; } + bus->curr_freq = dev_pm_opp_get_freq(opp); rcu_read_unlock();

return 0;