mfd: madera: work around false-positive -Wininitialized warning

[PATCH] mfd: madera: work around false-positive -Wininitialized warning

Posted by Arnd Bergmann 1 month, 4 weeks ago

From: Arnd Bergmann <arnd@arndb.de>

clang-21 warns about one uninitialized variable getting dereferenced
in madera_dev_init:

drivers/mfd/madera-core.c:739:10: error: variable 'mfd_devs' is uninitialized when used here [-Werror,-Wuninitialized]
  739 |                               mfd_devs, n_devs,
      |                               ^~~~~~~~
drivers/mfd/madera-core.c:459:33: note: initialize the variable 'mfd_devs' to silence this warning
  459 |         const struct mfd_cell *mfd_devs;
      |                                        ^
      |                                         = NULL

The code is actually correct here because n_devs is only nonzero
when mfd_devs is a valid pointer, but this is impossible for the
compiler to see reliably.

Change the logic to check for the pointer as well, to make this easier
for the compiler to follow.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/mfd/madera-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c
index bdbd5bfc9714..2f74a8c644a3 100644
--- a/drivers/mfd/madera-core.c
+++ b/drivers/mfd/madera-core.c
@@ -456,7 +456,7 @@ int madera_dev_init(struct madera *madera)
 	struct device *dev = madera->dev;
 	unsigned int hwid;
 	int (*patch_fn)(struct madera *) = NULL;
-	const struct mfd_cell *mfd_devs;
+	const struct mfd_cell *mfd_devs = NULL;
 	int n_devs = 0;
 	int i, ret;
 
@@ -670,7 +670,7 @@ int madera_dev_init(struct madera *madera)
 		goto err_reset;
 	}
 
-	if (!n_devs) {
+	if (!n_devs || !mfd_devs) {
 		dev_err(madera->dev, "Device ID 0x%x not a %s\n", hwid,
 			madera->type_name);
 		ret = -ENODEV;
-- 
2.39.5

Re: (subset) [PATCH] mfd: madera: work around false-positive -Wininitialized warning

Posted by Lee Jones 1 month ago

On Thu, 07 Aug 2025 09:19:28 +0200, Arnd Bergmann wrote:
> clang-21 warns about one uninitialized variable getting dereferenced
> in madera_dev_init:
> 
> drivers/mfd/madera-core.c:739:10: error: variable 'mfd_devs' is uninitialized when used here [-Werror,-Wuninitialized]
>   739 |                               mfd_devs, n_devs,
>       |                               ^~~~~~~~
> drivers/mfd/madera-core.c:459:33: note: initialize the variable 'mfd_devs' to silence this warning
>   459 |         const struct mfd_cell *mfd_devs;
>       |                                        ^
>       |                                         = NULL
> 
> [...]

Applied, thanks!

[1/1] mfd: madera: work around false-positive -Wininitialized warning
      commit: 3105933c2cf5e2e1908d31500fff72e28e0d94bf

--
Lee Jones [李琼斯]

Re: [PATCH] mfd: madera: work around false-positive -Wininitialized warning

Posted by Richard Fitzgerald 1 month, 4 weeks ago

On 07/08/2025 8:19 am, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> clang-21 warns about one uninitialized variable getting dereferenced
> in madera_dev_init:
> 
> drivers/mfd/madera-core.c:739:10: error: variable 'mfd_devs' is uninitialized when used here [-Werror,-Wuninitialized]
>    739 |                               mfd_devs, n_devs,
>        |                               ^~~~~~~~
> drivers/mfd/madera-core.c:459:33: note: initialize the variable 'mfd_devs' to silence this warning
>    459 |         const struct mfd_cell *mfd_devs;
>        |                                        ^
>        |                                         = NULL
> 
> The code is actually correct here because n_devs is only nonzero
> when mfd_devs is a valid pointer, but this is impossible for the
> compiler to see reliably.
> 
> Change the logic to check for the pointer as well, to make this easier
> for the compiler to follow.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   drivers/mfd/madera-core.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c
> index bdbd5bfc9714..2f74a8c644a3 100644
> --- a/drivers/mfd/madera-core.c
> +++ b/drivers/mfd/madera-core.c
> @@ -456,7 +456,7 @@ int madera_dev_init(struct madera *madera)
>   	struct device *dev = madera->dev;
>   	unsigned int hwid;
>   	int (*patch_fn)(struct madera *) = NULL;
> -	const struct mfd_cell *mfd_devs;
> +	const struct mfd_cell *mfd_devs = NULL;
>   	int n_devs = 0;
>   	int i, ret;
>   
> @@ -670,7 +670,7 @@ int madera_dev_init(struct madera *madera)
>   		goto err_reset;
>   	}
>   
> -	if (!n_devs) {
> +	if (!n_devs || !mfd_devs) {
>   		dev_err(madera->dev, "Device ID 0x%x not a %s\n", hwid,
>   			madera->type_name);
>   		ret = -ENODEV;
Reviewed-by: Richard Fitzgerald <rf@opensource.cirrus.com>