2021-07-02 11:31:21

by Colin King

[permalink] [raw]
Subject: [PATCH] iavf: remove redundant null check on key

From: Colin Ian King <[email protected]>

The null check on pointer key has already been performed at the
start of the function and this leads to a return of -EOPNOTSUPP.
The second null check on key is therefore always false, it is
redundant and can be removed.

Addresses-Coverity: ("Logically dead code")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/net/ethernet/intel/iavf/iavf_ethtool.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
index af43fbd8cb75..70193d8d54ed 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
@@ -1873,8 +1873,7 @@ static int iavf_set_rxfh(struct net_device *netdev, const u32 *indir,
if (!indir)
return 0;

- if (key)
- memcpy(adapter->rss_key, key, adapter->rss_key_size);
+ memcpy(adapter->rss_key, key, adapter->rss_key_size);

/* Each 32 bits pointed by 'indir' is stored with a lut entry */
for (i = 0; i < adapter->rss_lut_size; i++)
--
2.31.1


2021-07-02 18:46:12

by kernel test robot

[permalink] [raw]
Subject: Re: [PATCH] iavf: remove redundant null check on key

Hi Colin,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tnguy-next-queue/dev-queue]
[also build test WARNING on v5.13 next-20210701]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Colin-King/iavf-remove-redundant-null-check-on-key/20210702-192826
base: https://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue.git dev-queue
config: ia64-allmodconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/59ac04f9a577d107d282cd2c5ef80272a7ad40f7
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Colin-King/iavf-remove-redundant-null-check-on-key/20210702-192826
git checkout 59ac04f9a577d107d282cd2c5ef80272a7ad40f7
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

All warnings (new ones prefixed by >>):

drivers/net/ethernet/intel/iavf/iavf_ethtool.c: In function 'iavf_set_rxfh':
>> drivers/net/ethernet/intel/iavf/iavf_ethtool.c:1912:2: warning: argument 2 null where non-null expected [-Wnonnull]
1912 | memcpy(adapter->rss_key, key, adapter->rss_key_size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from include/linux/string.h:21,
from include/linux/bitmap.h:10,
from include/linux/cpumask.h:12,
from include/linux/smp.h:13,
from include/linux/lockdep.h:14,
from include/linux/spinlock.h:59,
from include/linux/mmzone.h:8,
from include/linux/gfp.h:6,
from include/linux/umh.h:4,
from include/linux/kmod.h:9,
from include/linux/module.h:16,
from drivers/net/ethernet/intel/iavf/iavf.h:7,
from drivers/net/ethernet/intel/iavf/iavf_ethtool.c:5:
arch/ia64/include/asm/string.h:19:14: note: in a call to function 'memcpy' declared here
19 | extern void *memcpy (void *, const void *, __kernel_size_t);
| ^~~~~~


vim +1912 drivers/net/ethernet/intel/iavf/iavf_ethtool.c

4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1888
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1889 /**
129cf89e585676 drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg 2018-09-14 1890 * iavf_set_rxfh - set the rx flow hash indirection table
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1891 * @netdev: network interface device structure
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1892 * @indir: indirection table
2cda3f3be5c2f6 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch Williams 2014-11-11 1893 * @key: hash key
f5254429e1756a drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Jacob Keller 2018-04-20 1894 * @hfunc: hash function to use
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1895 *
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1896 * Returns -EINVAL if the table specifies an inavlid queue id, otherwise
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1897 * returns 0 after programming the table.
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1898 **/
129cf89e585676 drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg 2018-09-14 1899 static int iavf_set_rxfh(struct net_device *netdev, const u32 *indir,
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1900 const u8 *key, const u8 hfunc)
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1901 {
129cf89e585676 drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg 2018-09-14 1902 struct iavf_adapter *adapter = netdev_priv(netdev);
2c86ac3c70794f drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Helin Zhang 2015-10-27 1903 u16 i;
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1904
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1905 /* We do not allow change in unsupported parameters */
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1906 if (key ||
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1907 (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP))
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1908 return -EOPNOTSUPP;
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1909 if (!indir)
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1910 return 0;
892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1911
43a3d9ba34c9ca drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch Williams 2016-04-12 @1912 memcpy(adapter->rss_key, key, adapter->rss_key_size);
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1913
2c86ac3c70794f drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Helin Zhang 2015-10-27 1914 /* Each 32 bits pointed by 'indir' is stored with a lut entry */
43a3d9ba34c9ca drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch Williams 2016-04-12 1915 for (i = 0; i < adapter->rss_lut_size; i++)
43a3d9ba34c9ca drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch Williams 2016-04-12 1916 adapter->rss_lut[i] = (u8)(indir[i]);
2c86ac3c70794f drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Helin Zhang 2015-10-27 1917
129cf89e585676 drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg 2018-09-14 1918 return iavf_config_rss(adapter);
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1919 }
4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1920

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]


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2021-07-03 09:53:49

by Dan Carpenter

[permalink] [raw]
Subject: Re: [PATCH] iavf: remove redundant null check on key

On Sat, Jul 03, 2021 at 02:43:46AM +0800, kernel test robot wrote:
> 129cf89e585676 drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg 2018-09-14 1899 static int iavf_set_rxfh(struct net_device *netdev, const u32 *indir,
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1900 const u8 *key, const u8 hfunc)
> 4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1901 {
> 129cf89e585676 drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg 2018-09-14 1902 struct iavf_adapter *adapter = netdev_priv(netdev);
> 2c86ac3c70794f drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Helin Zhang 2015-10-27 1903 u16 i;
> 4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch A Williams 2014-04-01 1904
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1905 /* We do not allow change in unsupported parameters */
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1906 if (key ||
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1907 (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP))
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1908 return -EOPNOTSUPP;
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1909 if (!indir)
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1910 return 0;
> 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Eyal Perry 2014-12-02 1911
> 43a3d9ba34c9ca drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c Mitch Williams 2016-04-12 @1912 memcpy(adapter->rss_key, key, adapter->rss_key_size);

Heh... There have been a bunch of patches modifying the behavior if
"key" is non-NULL and no one noticed that it's actually impossible.

:P

regards,
dan carpenter

2021-07-07 23:50:38

by Tony Nguyen

[permalink] [raw]
Subject: Re: [PATCH] iavf: remove redundant null check on key

On Sat, 2021-07-03 at 12:49 +0300, Dan Carpenter wrote:
> On Sat, Jul 03, 2021 at 02:43:46AM +0800, kernel test robot wrote:
> > 129cf89e585676
> > drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg
> > 2018-09-14 1899 static int iavf_set_rxfh(struct net_device
> > *netdev, const u32 *indir,
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1900 const u8 *key,
> > const u8 hfunc)
> > 4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Mitch A Williams 2014-04-01 1901 {
> > 129cf89e585676
> > drivers/net/ethernet/intel/iavf/i40evf_ethtool.c Jesse Brandeburg
> > 2018-09-14 1902 struct iavf_adapter *adapter =
> > netdev_priv(netdev);
> > 2c86ac3c70794f drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Helin Zhang 2015-10-27 1903 u16 i;
> > 4e9dc31f696ae8 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Mitch A Williams 2014-04-01 1904
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1905 /* We do not allow change in
> > unsupported parameters */
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1906 if (key ||
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1907 (hfunc !=
> > ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP))
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1908 return -EOPNOTSUPP;
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1909 if (!indir)
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1910 return 0;
> > 892311f66f2411 drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Eyal Perry 2014-12-02 1911
> > 43a3d9ba34c9ca drivers/net/ethernet/intel/i40evf/i40evf_ethtool.c
> > Mitch Williams 2016-04-12 @1912 memcpy(adapter->rss_key, key,
> > adapter->rss_key_size);
>
> Heh... There have been a bunch of patches modifying the behavior if
> "key" is non-NULL and no one noticed that it's actually impossible.

We are capable of supporting a key change. We're working on a patch to
resolve the check and allow the key to be changed.

- Tony

> :P
>
> regards,
> dan carpenter
>