[PATCH 3.18 087/183] clk: Really fix deadlock with mmap_sem

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxx>
Fixes: 6314b6796e3c "clk: Don't hold prepare_lock across debugfs creation"
Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Michael Turquette <mturquette@xxxxxxxxxx>
[mturquette@xxxxxxxxxx: removed lockdep_assert]
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -240,7 +240,6 @@ 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;
@@ -1944,7 +1943,6 @@ 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
@@ -1979,6 +1977,9 @@ int __clk_init(struct device *dev, struc
 out:
 	clk_prepare_unlock();
 
+	if (!ret)
+		clk_debug_register(clk);
+
 	return ret;
 }
 


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/