[PATCH 3.18 088/183] clk: Dont try to use a struct clk* after it could have been freed

Greg Kroah-Hartman
2015-01-25T18:47:28Z

From: Tomeu Vizoso <tomeu.vizoso@collabora.com>

commit 10cdfe54dab034311c8e2fad9ba2dffbe616caa9 upstream.

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@collabora.com>
Fixes: fcb0ee6a3d33 ("clk: Implement clk_unregister")
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/clk/clk.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2274,14 +2274,17 @@ 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 ***/