On Friday, January 09, 2015 09:27:57 AM Krzysztof Kozlowski wrote:
> Add lockdep asserts for holding the RCU lock when calling
> dev_pm_opp_get_freq() and dev_pm_opp_get_voltage() to aid in detecting
> RCU misuses.
>
> These are called often after dev_pm_opp_find_freq_ceil/exact() which
> already asserts for RCU lock. However one could make an error by
> releasing lock too early - just after dev_pm_opp_find_freq_ceil().
>
> Signed-off-by: Krzysztof Kozlowski <[email protected]>
Queued up for 3.20, thanks!
> ---
> drivers/base/power/opp.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index 106c69359306..842d31e24eee 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -169,6 +169,8 @@ unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp
> *opp)
> struct dev_pm_opp *tmp_opp;
> unsigned long v = 0;
>
> + opp_rcu_lockdep_assert();
> +
> tmp_opp = rcu_dereference(opp);
> if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
> pr_err("%s: Invalid parameters\n", __func__);
> @@ -199,6 +201,8 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
> struct dev_pm_opp *tmp_opp;
> unsigned long f = 0;
>
> + opp_rcu_lockdep_assert();
> +
> tmp_opp = rcu_dereference(opp);
> if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
> pr_err("%s: Invalid parameters\n", __func__);
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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