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[3/4] PM / devfreq: add locking documentation for recommended_opp

Message ID 1358538755-29109-4-git-send-email-nm@ti.com (mailing list archive)
State New, archived
Headers show

Commit Message

Nishanth Menon Jan. 18, 2013, 7:52 p.m. UTC
OPP pointers are protected by RCU locks, the pointer validity is
permissible only under the section of rcu_read_lock to rcu_read_unlock

Add documentation to the effect.

Signed-off-by: Nishanth Menon <nm@ti.com>
---
 drivers/devfreq/devfreq.c |    5 +++++
 1 file changed, 5 insertions(+)
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Patch

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 53766f3..3b36797 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -994,6 +994,11 @@  module_exit(devfreq_exit);
  * @freq:	The frequency given to target function
  * @flags:	Flags handed from devfreq framework.
  *
+ * Locking: This function must be called under rcu_read_lock(). opp is a rcu
+ * protected pointer. The reason for the same is that the opp pointer which is
+ * returned will remain valid for use with opp_get_{voltage, freq} only while
+ * under the locked area. The pointer returned must be used prior to unlocking
+ * with rcu_read_unlock() to maintain the integrity of the pointer.
  */
 struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
 				    u32 flags)