linux-kernel - [PATCH v4 3/8] clk: Don't try to use a struct clk* after it could have been freed

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Message-Id: <1413812442-24956-4-git-send-email-tomeu.vizoso@collabora.com>
Date:	Mon, 20 Oct 2014 15:40:03 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	Mike Turquette <mturquette@...aro.org>
Cc:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Tomeu Vizoso <tomeu.vizoso@...labora.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 3/8] clk: Don't try to use a struct clk* after it could have been freed

As __clk_release could call kfree on clk and then we wouldn't have a safe way
of getting the module that owns the clock.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
Fixes: fcb0ee6a3d33 ("clk: Implement clk_unregister")

---

v4:	* Move out module_put from the critical section
	* Add Fixes: tag
---
 drivers/clk/clk.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index d0712b7..d2f0fb6 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2268,14 +2268,17 @@ int __clk_get(struct clk *clk)
 
 void __clk_put(struct clk *clk)
 {
+	struct module *owner;
+
 	if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
 		return;
 
 	clk_prepare_lock();
+	owner = clk->owner;
 	kref_put(&clk->ref, __clk_release);
 	clk_prepare_unlock();
 
-	module_put(clk->owner);
+	module_put(owner);
 }
 
 /***        clk rate change notifiers        ***/
-- 
1.9.3

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