There is currently a race condition in the device tree part of clk_get() function, since the pointer returned from of_clk_get_by_name() may become invalid before __clk_get() call. I.e. due to the clock provider driver remove() callback being called in between of_clk_get_by_name() and __clk_get().
Fix this by doing both the look up and __clk_get() operations with the clock providers list mutex held. This ensures that the clock pointer returned from __of_clk_get_from_provider() call and passed to __clk_get() is valid, as long as the clock supplier module first removes its clock provider instance and then does clk_unregister() on the corresponding clocks. Signed-off-by: Sylwester Nawrocki <[email protected]> Signed-off-by: Kyungmin Park <[email protected]> Reviewed-by: Mike Turquette <[email protected]> --- Changes since v1: - include "clk.h". --- drivers/clk/clkdev.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c index 442a313..48f6721 100644 --- a/drivers/clk/clkdev.c +++ b/drivers/clk/clkdev.c @@ -21,6 +21,8 @@ #include <linux/clkdev.h> #include <linux/of.h> +#include "clk.h" + static LIST_HEAD(clocks); static DEFINE_MUTEX(clocks_mutex); @@ -39,7 +41,13 @@ struct clk *of_clk_get(struct device_node *np, int index) if (rc) return ERR_PTR(rc); - clk = of_clk_get_from_provider(&clkspec); + of_clk_lock(); + clk = __of_clk_get_from_provider(&clkspec); + + if (!IS_ERR(clk) && !__clk_get(clk)) + clk = ERR_PTR(-ENOENT); + + of_clk_unlock(); of_node_put(clkspec.np); return clk; } @@ -157,7 +165,7 @@ struct clk *clk_get(struct device *dev, const char *con_id) if (dev) { clk = of_clk_get_by_name(dev->of_node, con_id); - if (!IS_ERR(clk) && __clk_get(clk)) + if (!IS_ERR(clk)) return clk; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
