2016-10-24 15:29:48

by Arnd Bergmann

Subject: [PATCH] mtd: ichxrom: maybe-uninitialized with gcc-4.9

pci_read_config_word() might fail and not initialize its output,
as pointed out by older versions of gcc when using the -Wmaybe-unintialized
flag:

drivers/mtd/maps/ichxrom.c: In function ‘ichxrom_cleanup’:
drivers/mtd/maps/ichxrom.c:63:2: error: ‘word’ is used uninitialized in this function [-Werror=uninitialized]

This is apparently a correct warning, though it does not show up
with newer compilers. Changing the code to not attempt to write
back uninitialized data into PCI config space is a correct
fix for the problem and avoids the warning.

Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/mtd/maps/ichxrom.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/maps/ichxrom.c b/drivers/mtd/maps/ichxrom.c
index e17d02ae03f0..976d42f63aef 100644
--- a/drivers/mtd/maps/ichxrom.c
+++ b/drivers/mtd/maps/ichxrom.c
@@ -57,10 +57,12 @@ static void ichxrom_cleanup(struct ichxrom_window *window)
{
struct ichxrom_map_info *map, *scratch;
u16 word;
+ int ret;

/* Disable writes through the rom window */
- pci_read_config_word(window->pdev, BIOS_CNTL, &word);
- pci_write_config_word(window->pdev, BIOS_CNTL, word & ~1);
+ ret = pci_read_config_word(window->pdev, BIOS_CNTL, &word);
+ if (!ret)
+ pci_write_config_word(window->pdev, BIOS_CNTL, word & ~1);
pci_dev_put(window->pdev);

/* Free all of the mtd devices */
--
2.9.0

2016-10-24 20:49:00

by Marek Vasut

Subject: Re: [PATCH] mtd: ichxrom: maybe-uninitialized with gcc-4.9

On 10/24/2016 05:28 PM, Arnd Bergmann wrote:
> pci_read_config_word() might fail and not initialize its output,
> as pointed out by older versions of gcc when using the -Wmaybe-unintialized
> flag:
>
> drivers/mtd/maps/ichxrom.c: In function ‘ichxrom_cleanup’:
> drivers/mtd/maps/ichxrom.c:63:2: error: ‘word’ is used uninitialized in this function [-Werror=uninitialized]
>
> This is apparently a correct warning, though it does not show up
> with newer compilers. Changing the code to not attempt to write
> back uninitialized data into PCI config space is a correct
> fix for the problem and avoids the warning.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Reviewed-by: Marek Vasut <[email protected]>

> ---
> drivers/mtd/maps/ichxrom.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/maps/ichxrom.c b/drivers/mtd/maps/ichxrom.c
> index e17d02ae03f0..976d42f63aef 100644
> --- a/drivers/mtd/maps/ichxrom.c
> +++ b/drivers/mtd/maps/ichxrom.c
> @@ -57,10 +57,12 @@ static void ichxrom_cleanup(struct ichxrom_window *window)
> {
> struct ichxrom_map_info *map, *scratch;
> u16 word;
> + int ret;
>
> /* Disable writes through the rom window */
> - pci_read_config_word(window->pdev, BIOS_CNTL, &word);
> - pci_write_config_word(window->pdev, BIOS_CNTL, word & ~1);
> + ret = pci_read_config_word(window->pdev, BIOS_CNTL, &word);
> + if (!ret)
> + pci_write_config_word(window->pdev, BIOS_CNTL, word & ~1);
> pci_dev_put(window->pdev);
>
> /* Free all of the mtd devices */
>


--
Best regards,
Marek Vasut