[PATCH 3.14 40/98] clk: Really fix deadlock with mmap_sem

Greg Kroah-Hartman
2015-01-25T19:21:42Z

From: Stephen Boyd <sboyd@codeaurora.org>

commit 89f7e9de59bf3e3cda2e00de12c66db22675a7cf upstream.

Commit 6314b6796e3c (clk: Don't hold prepare_lock across debugfs
creation, 2014-09-04) forgot to update one place where we hold
the prepare_lock while creating debugfs directories. This means
we still have the chance of a deadlock that the commit was trying
to fix. Actually fix it by moving the debugfs creation outside
the prepare_lock.

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fixes: 6314b6796e3c "clk: Don't hold prepare_lock across debugfs creation"
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
[mturquette@linaro.org: removed lockdep_assert]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/clk/clk.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -230,7 +230,6 @@ static const struct file_operations clk_
.release = single_release,
};

-/* caller must hold prepare_lock */
static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
{
struct dentry *d;
@@ -1902,7 +1901,6 @@ int __clk_init(struct device *dev, struc
else
clk->rate = 0;

- clk_debug_register(clk);
/*
* walk the list of orphan clocks and reparent any that are children of
* this clock
@@ -1937,6 +1935,9 @@ int __clk_init(struct device *dev, struc
out:
clk_prepare_unlock();

+ if (!ret)
+ clk_debug_register(clk);
+
return ret;
}