diff mbox series

iwlwifi: pcie: fix constant-conversion warning

Message ID 20211029154253.3824677-1-arnd@kernel.org (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series iwlwifi: pcie: fix constant-conversion warning | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Arnd Bergmann Oct. 29, 2021, 3:42 p.m. UTC 
From: Arnd Bergmann <arnd@arndb.de>

clang points out a potential issue with integer overflow when
the iwl_dev_info_table[] array is empty:

drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
        for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
               ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~

This is still harmless, as the loop correctly terminates, but adding
an (int) cast makes that clearer to the compiler.

Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/wireless/intel/iwlwifi/pcie/drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Kalle Valo Oct. 31, 2021, 7:06 a.m. UTC | #1 
Arnd Bergmann <arnd@kernel.org> writes:

> From: Arnd Bergmann <arnd@arndb.de>
>
> clang points out a potential issue with integer overflow when
> the iwl_dev_info_table[] array is empty:
>
> drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
>         for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
>                ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
>
> This is still harmless, as the loop correctly terminates, but adding
> an (int) cast makes that clearer to the compiler.
>
> Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Luca, can I take this to wireless-drivers? Ack?
Luca Coelho Nov. 1, 2021, 7:29 a.m. UTC | #2 
On Sun, 2021-10-31 at 09:06 +0200, Kalle Valo wrote:
> Arnd Bergmann <arnd@kernel.org> writes:
> 
> > From: Arnd Bergmann <arnd@arndb.de>
> > 
> > clang points out a potential issue with integer overflow when
> > the iwl_dev_info_table[] array is empty:
> > 
> > drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
> >         for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
> >                ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
> > 
> > This is still harmless, as the loop correctly terminates, but adding
> > an (int) cast makes that clearer to the compiler.
> > 
> > Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> 
> Luca, can I take this to wireless-drivers? Ack?

Yes, please do.

Thanks.

Acked-by: Luca Coelho <luciano.coelho@intel.com>

--
Cheers,
Luca.
Luca Coelho Nov. 1, 2021, 7:32 a.m. UTC | #3 
On Mon, 2021-11-01 at 09:29 +0200, Luciano Coelho wrote:
> On Sun, 2021-10-31 at 09:06 +0200, Kalle Valo wrote:
> > Arnd Bergmann <arnd@kernel.org> writes:
> > 
> > > From: Arnd Bergmann <arnd@arndb.de>
> > > 
> > > clang points out a potential issue with integer overflow when
> > > the iwl_dev_info_table[] array is empty:
> > > 
> > > drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
> > >         for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
> > >                ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
> > > 
> > > This is still harmless, as the loop correctly terminates, but adding
> > > an (int) cast makes that clearer to the compiler.
> > > 
> > > Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > 
> > Luca, can I take this to wireless-drivers? Ack?
> 
> Yes, please do.
> 
> Thanks.
> 
> Acked-by: Luca Coelho <luciano.coelho@intel.com>

Actually, wouldn't it be simpler to change the declaration of i to be
unsigned int?

--
Luca.
diff mbox series

Patch

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/drv.c b/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
index c574f041f096..81e8f2fc4982 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
@@ -1341,7 +1341,7 @@  iwl_pci_find_dev_info(u16 device, u16 subsystem_device,
 {
 	int i;
 
-	for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
+	for (i = (int)ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
 		const struct iwl_dev_info *dev_info = &iwl_dev_info_table[i];
 
 		if (dev_info->device != (u16)IWL_CFG_ANY &&