[PATCH][V2] reset: remove redundant null check on pointer dev

[PATCH][V2] reset: remove redundant null check on pointer dev

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Pointer dev is being dereferenced when passed to the inlined
functon dev_name, however, dev is later being null checked
so at first this seems like a potential null pointer dereference.

In fact, _reset_control_get_from_lookup is only ever called from
__reset_control_get, right after checking dev->of_node hence
dev can never be null.  Clean this up by removing the redundant
null check.

Thanks to Philipp Zabel for spotting that dev can never be null.

Addresses-Coverity: ("Dereference before null check")
Fixes: 6691dffab0ab ("reset: add support for non-DT systems")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---

V2: remove null check point, it is redundant.

---
 drivers/reset/core.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index 81ea77cba123..921f4bbbad8a 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -694,9 +694,6 @@ __reset_control_get_from_lookup(struct device *dev, const char *con_id,
 	const char *dev_id = dev_name(dev);
 	struct reset_control *rstc = NULL;
 
-	if (!dev)
-		return ERR_PTR(-EINVAL);
-
 	mutex_lock(&reset_lookup_mutex);
 
 	list_for_each_entry(lookup, &reset_lookup_list, list) {
-- 
2.20.1

Re: [PATCH][V2] reset: remove redundant null check on pointer dev

[Bartosz Golaszewski]

pt., 10 maj 2019 o 11:58 Colin King <colin.king@canonical.com> napisał(a):
>
> From: Colin Ian King <colin.king@canonical.com>
>
> Pointer dev is being dereferenced when passed to the inlined
> functon dev_name, however, dev is later being null checked
> so at first this seems like a potential null pointer dereference.
>
> In fact, _reset_control_get_from_lookup is only ever called from
> __reset_control_get, right after checking dev->of_node hence
> dev can never be null.  Clean this up by removing the redundant
> null check.
>
> Thanks to Philipp Zabel for spotting that dev can never be null.
>
> Addresses-Coverity: ("Dereference before null check")
> Fixes: 6691dffab0ab ("reset: add support for non-DT systems")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>
> V2: remove null check point, it is redundant.
>
> ---
>  drivers/reset/core.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/drivers/reset/core.c b/drivers/reset/core.c
> index 81ea77cba123..921f4bbbad8a 100644
> --- a/drivers/reset/core.c
> +++ b/drivers/reset/core.c
> @@ -694,9 +694,6 @@ __reset_control_get_from_lookup(struct device *dev, const char *con_id,
>         const char *dev_id = dev_name(dev);
>         struct reset_control *rstc = NULL;
>
> -       if (!dev)
> -               return ERR_PTR(-EINVAL);
> -
>         mutex_lock(&reset_lookup_mutex);
>
>         list_for_each_entry(lookup, &reset_lookup_list, list) {
> --
> 2.20.1
>

Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Re: [PATCH][V2] reset: remove redundant null check on pointer dev

[Philipp Zabel]

On Fri, 2019-05-10 at 12:14 +0200, Bartosz Golaszewski wrote:
> pt., 10 maj 2019 o 11:58 Colin King <colin.king@canonical.com> napisał(a):
> > 
> > From: Colin Ian King <colin.king@canonical.com>
> > 
> > Pointer dev is being dereferenced when passed to the inlined
> > functon dev_name, however, dev is later being null checked
> > so at first this seems like a potential null pointer dereference.
> > 
> > In fact, _reset_control_get_from_lookup is only ever called from
> > __reset_control_get, right after checking dev->of_node hence
> > dev can never be null.  Clean this up by removing the redundant
> > null check.
> > 
> > Thanks to Philipp Zabel for spotting that dev can never be null.
> > 
> > Addresses-Coverity: ("Dereference before null check")
> > Fixes: 6691dffab0ab ("reset: add support for non-DT systems")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
[...]
> Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Thank you both, applied to reset/fixes.

regards
Philipp