On Mon, Dec 15, 2014 at 9:33 PM, Viresh Kumar <[email protected]> wrote: > On 16 December 2014 at 06:20, Dmitry Torokhov <[email protected]> wrote: >> dev_pm_opp_get_opp_count() must be called with RCU lock held. >> >> Signed-off-by: Dmitry Torokhov <[email protected]> >> --- >> >> Not tested at all... >> >> drivers/cpufreq/imx6q-cpufreq.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/cpufreq/imx6q-cpufreq.c >> b/drivers/cpufreq/imx6q-cpufreq.c >> index 380a90d..851d4fd 100644 >> --- a/drivers/cpufreq/imx6q-cpufreq.c >> +++ b/drivers/cpufreq/imx6q-cpufreq.c >> @@ -200,7 +200,9 @@ static int imx6q_cpufreq_probe(struct platform_device >> *pdev) >> * Just, incase the platform did not supply the OPP >> * table, it will try to get it. >> */ >> + rcu_read_lock(); >> num = dev_pm_opp_get_opp_count(cpu_dev); >> + rcu_read_unlock(); >> if (num < 0) { >> ret = of_init_opp_table(cpu_dev); >> if (ret < 0) { >> @@ -211,7 +213,9 @@ static int imx6q_cpufreq_probe(struct platform_device >> *pdev) >> /* Because we have added the OPPs here, we must free them */ >> free_opp = true; >> >> + rcu_read_lock(); >> num = dev_pm_opp_get_opp_count(cpu_dev); >> + rcu_read_unlock(); >> if (num < 0) { >> ret = num; >> dev_err(cpu_dev, "no OPP table is found: %d\n", ret); > > This one looks fine for sure but I was wondering for the users which just > need to call opp-count from under the locks, what about something like: > > dev_pm_opp_get_opp_count_locked() ?
Yeah, for the majority of callers taking the lock won't hurt as they call it in their init code. Thanks, Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
