From: Chander Kashyap k.chander@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.
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 nm@ti.com Signed-off-by: Chander Kashyap k.chander@samsung.com Signed-off-by: Inderpal Singh inderpal.s@samsung.com Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- I took some rest before sending V6, just to make sure I don't send another version in hurry with any obvious mistake.
V5->V6: - Remove parenthesis around initialization of 'ret'. - s/Returns/Return - Fix checkpatch.pl --strict warning: 'Alignment should match open parenthesis' - Tried improving changelog..
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 faae9cf..89ced95 100644 --- a/drivers/base/power/opp.c +++ b/drivers/base/power/opp.c @@ -393,6 +393,13 @@ 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) { @@ -442,15 +449,31 @@ 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);