[resend] clk: get matching entry under lock in of_clk_init()

Message ID 52163CE3.8000806@linaro.org
State New
Headers show

Commit Message

Alex Elder Aug. 22, 2013, 4:31 p.m.
Currently of_clk_init() finds a matching device node while holding
the device tree spinlock.  When a matching device node is found, the
lock is dropped and then re-acquired in order to get a reference
to the matching device id structure.

Acquiring the spinlock twice is unnecessary (and it opens a
vulnerable window that could conceivably lead to errors).

There already exists an interface for both finding and taking a
reference to a device id under lock, so use it.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Christian Daudt <csd@broadcom.com>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
---
 drivers/clk/clk.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Mike Turquette Aug. 27, 2013, 11:06 p.m. | #1
Quoting Alex Elder (2013-08-22 09:31:31)
> Currently of_clk_init() finds a matching device node while holding
> the device tree spinlock.  When a matching device node is found, the
> lock is dropped and then re-acquired in order to get a reference
> to the matching device id structure.
> 
> Acquiring the spinlock twice is unnecessary (and it opens a
> vulnerable window that could conceivably lead to errors).
> 
> There already exists an interface for both finding and taking a
> reference to a device id under lock, so use it.
> 
> Signed-off-by: Alex Elder <elder@linaro.org>
> Reviewed-by: Christian Daudt <csd@broadcom.com>
> Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
> Reviewed-by: Matt Porter <matt.porter@linaro.org>

Thanks for the fix. Taken into clk-next.

Regards,
Mike

> ---
>  drivers/clk/clk.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 56a00db..760ab1d 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -2116,13 +2116,13 @@ EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
>   */
>  void __init of_clk_init(const struct of_device_id *matches)
>  {
> +       const struct of_device_id *match;
>         struct device_node *np;
> 
>         if (!matches)
>                 matches = __clk_of_table;
> 
> -       for_each_matching_node(np, matches) {
> -               const struct of_device_id *match = of_match_node(matches, np);
> +       for_each_matching_node_and_match(np, matches, &match) {
>                 of_clk_init_cb_t clk_init_cb = match->data;
>                 clk_init_cb(np);
>         }
> -- 
> 1.7.9.5

Patch

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 56a00db..760ab1d 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2116,13 +2116,13 @@  EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
  */
 void __init of_clk_init(const struct of_device_id *matches)
 {
+	const struct of_device_id *match;
 	struct device_node *np;

 	if (!matches)
 		matches = __clk_of_table;

-	for_each_matching_node(np, matches) {
-		const struct of_device_id *match = of_match_node(matches, np);
+	for_each_matching_node_and_match(np, matches, &match) {
 		of_clk_init_cb_t clk_init_cb = match->data;
 		clk_init_cb(np);
 	}