linux-kernel - [PATCH] clk: Use lockdep asserts to find missing hold of prepare

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Date:	Fri, 09 Jan 2015 09:28:10 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Mike Turquette <mturquette@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org
Cc:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Subject: [PATCH] clk: Use lockdep asserts to find missing hold of prepare_lock

Add lockdep asserts for holding the prepare_lock to all functions
marking this as a requirement in description. Add this to private and
exported functions so all locking misuse could be detected during
debugging.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
---
 drivers/clk/clk.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index f4963b7d4e17..cdbfaa34ace4 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -432,6 +432,8 @@ static void clk_unprepare_unused_subtree(struct clk *clk)
 {
 	struct clk *child;
 
+	lockdep_assert_held(&prepare_lock);
+
 	if (!clk)
 		return;
 
@@ -458,6 +460,8 @@ static void clk_disable_unused_subtree(struct clk *clk)
 	struct clk *child;
 	unsigned long flags;
 
+	lockdep_assert_held(&prepare_lock);
+
 	if (!clk)
 		goto out;
 
@@ -947,6 +951,8 @@ unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
 	struct clk *parent;
 	struct clk_hw *parent_hw;
 
+	lockdep_assert_held(&prepare_lock);
+
 	if (!clk)
 		return 0;
 
@@ -1040,6 +1046,8 @@ static void __clk_recalc_accuracies(struct clk *clk)
 	unsigned long parent_accuracy = 0;
 	struct clk *child;
 
+	lockdep_assert_held(&prepare_lock);
+
 	if (clk->parent)
 		parent_accuracy = clk->parent->accuracy;
 
@@ -1104,6 +1112,8 @@ static void __clk_recalc_rates(struct clk *clk, unsigned long msg)
 	unsigned long parent_rate = 0;
 	struct clk *child;
 
+	lockdep_assert_held(&prepare_lock);
+
 	old_rate = clk->rate;
 
 	if (clk->parent)
@@ -1297,6 +1307,8 @@ static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
 	unsigned long new_rate;
 	int ret = NOTIFY_DONE;
 
+	lockdep_assert_held(&prepare_lock);
+
 	new_rate = clk_recalc(clk, parent_rate);
 
 	/* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
@@ -2110,6 +2122,8 @@ static void __clk_release(struct kref *ref)
 	struct clk *clk = container_of(ref, struct clk, ref);
 	int i = clk->num_parents;
 
+	lockdep_assert_held(&prepare_lock);
+
 	kfree(clk->parents);
 	while (--i >= 0)
 		kfree(clk->parent_names[i]);
-- 
1.9.1

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