From 5a7efdacb9dda1c35fb414d57b3e16d520e2c0db Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Fri, 12 Apr 2019 11:31:42 -0700 Subject: [PATCH] clkdev: Hold clocks_mutex while iterating clocks list We recently introduced a change to support devm clk lookups. That change introduced a code-path that used clk_find() without holding the 'clocks_mutex'. Unfortunately, clk_find() iterates over the 'clocks' list and so we need to prevent the list from being modified at the same time. Do this by holding the mutex and checking to make sure it's held while iterating the list. Note, we don't really care if the lookup is freed after we find it with clk_find() because we're just doing a pointer comparison, but if we did care we would need to keep holding the mutex while we dereference the clk_lookup pointer. Fixes: 3eee6c7d119c ("clkdev: add managed clkdev lookup registration") Cc: Miquel Raynal Cc: Jerome Brunet Cc: Russell King Cc: Michael Turquette Cc: Jeffrey Hugo Cc: Chen-Yu Tsai Cc: Matti Vaittinen Acked-by: Matti Vaittinen Tested-by: Jeffrey Hugo Signed-off-by: Stephen Boyd --- drivers/clk/clkdev.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c index 8c4435c53f09..6e787cc9e5b9 100644 --- a/drivers/clk/clkdev.c +++ b/drivers/clk/clkdev.c @@ -46,6 +46,8 @@ static struct clk_lookup *clk_find(const char *dev_id, const char *con_id) if (con_id) best_possible += 1; + lockdep_assert_held(&clocks_mutex); + list_for_each_entry(p, &clocks, node) { match = 0; if (p->dev_id) { @@ -402,7 +404,10 @@ void devm_clk_release_clkdev(struct device *dev, const char *con_id, struct clk_lookup *cl; int rval; + mutex_lock(&clocks_mutex); cl = clk_find(dev_id, con_id); + mutex_unlock(&clocks_mutex); + WARN_ON(!cl); rval = devres_release(dev, devm_clkdev_release, devm_clk_match_clkdev, cl);