From 64ce854578de82e9e16280298562721ced971668 Mon Sep 17 00:00:00 2001 From: Chander Kashyap Date: Thu, 22 May 2014 10:36:26 +0530 Subject: [PATCH] PM / OPP: discard duplicate OPPs 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. We need to handle some duplication cases separately as returning error might not be the right thing always. The new list of return values for dev_pm_opp_add() are: 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 Acked-by: Nishanth Menon Signed-off-by: Chander Kashyap Signed-off-by: Inderpal Singh Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- 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 c539d70b97ab..39412c15db70 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. + * + * Return: + * 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 = opp->available && new_opp->u_volt == opp->u_volt ? + 0 : -EEXIST; + + 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); -- 2.30.2