On Tuesday, May 20, 2014 08:23:28 PM Viresh Kumar wrote:
> From: Chander Kashyap <k.chan...@samsung.com>
>
> We don't have any protection against addition of duplicate OPPs currently and
> in case some code tries to add them it will end up corrupting OPP tables.
>
> There can be many combinations in which we may end up trying duplicate OPPs:
> - both freq and volt are same, but earlier OPP may or may not be active.
> - only freq is same and volt is different.
>
> This patch tries to implement below logic for these cases:
>
> Return 0 if new OPP was duplicate of existing one (i.e. same freq and volt)
> and
> return -EEXIST if new OPP had same freq but different volt as of an existing
> OPP
> OR if both freq/volt were same but earlier OPP was disabled.
>
> Signed-off-by: Chander Kashyap <k.chan...@samsung.com>
> Signed-off-by: Inderpal Singh <inderpa...@samsung.com>
> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
> ---
> V4->V5:
> - Mention Return values under 'Return:' clause of doc style comment.
> - s/pr_warn/dev_warn
> - s/linrao/linaro in my email id :(
>
> drivers/base/power/opp.c | 27 +++++++++++++++++++++++++--
> 1 file changed, 25 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index 2553867..6a06d43 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -394,6 +394,13 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
> * to keep the integrity of the internal data structures. Callers should
> ensure
> * that this function is *NOT* called under RCU protection or in contexts
> where
> * mutex cannot be locked.
> + *
> + * Returns:
> + * 0: On success OR
> + * Duplicate OPPs (both freq and volt are same) and opp->available
> + * -EEXIST: Freq are same and volt are different OR
> + * Duplicate OPPs (both freq and volt are same) and !opp->available
> + * -ENOMEM: Memory allocation failure
> */
> int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long
> u_volt)
> {
> @@ -443,15 +450,31 @@ int dev_pm_opp_add(struct device *dev, unsigned long
> freq, unsigned long u_volt)
> new_opp->u_volt = u_volt;
> new_opp->available = true;
>
> - /* Insert new OPP in order of increasing frequency */
> + /*
> + * Insert new OPP in order of increasing frequency
> + * and discard if already present
> + */
> head = &dev_opp->opp_list;
> list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) {
> - if (new_opp->rate < opp->rate)
> + if (new_opp->rate <= opp->rate)
> break;
> else
> head = &opp->node;
> }
>
> + /* Duplicate OPPs ? */
> + if (new_opp->rate == opp->rate) {
> + int ret = (new_opp->u_volt == opp->u_volt) && opp->available ?
> + 0 : -EEXIST;
The parens are not necessary. And is the direction correct?
> +
> + dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq:
> %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
> + __func__, opp->rate, opp->u_volt, opp->available,
> + new_opp->rate, new_opp->u_volt, new_opp->available);
> + mutex_unlock(&dev_opp_list_lock);
> + kfree(new_opp);
> + return ret;
> + }
> +
> list_add_rcu(&new_opp->node, head);
> mutex_unlock(&dev_opp_list_lock);
>
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
