Re: drivers/net/usb/pegasus.c:461:2: warning: Value stored to 'ret' is never read [clang-analyzer-deadcode.DeadStores]

From: Pavel Skripkin
Date: Mon Aug 09 2021 - 07:06:20 EST


On 8/9/21 1:37 PM, kernel test robot wrote:

tree:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 85a90500f9a1717c4e142ce92e6c1cb1a339ec78
commit: 8a160e2e9aeb8318159b48701ad8a6e22274372d net: usb: pegasus:
Check the return value of get_geristers() and friends;
date: 4 days ago
:::::: branch date: 8 hours ago
:::::: commit date: 4 days ago
config: x86_64-randconfig-c001-20210808 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
41a6b50c25961addc04438b567ee1f4ef9e40f98)
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
# install x86_64 cross compiling tool for clang build
# apt-get install binutils-x86-64-linux-gnu
#
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8a160e2e9aeb8318159b48701ad8a6e22274372d
git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 8a160e2e9aeb8318159b48701ad8a6e22274372d
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross
ARCH=x86_64 clang-analyzer
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

Hi, @Petko!

For you not to scan all these warnings:

drivers/net/usb/pegasus.c:461:2: warning: Value stored to 'ret' is never read [clang-analyzer-deadcode.DeadStores]
ret = set_registers(pegasus, EthCtrl0, 3, data);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/usb/pegasus.c:461:2: note: Value stored to 'ret' is
never read
ret = set_registers(pegasus, EthCtrl0, 3, data);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is the real bug, I think. Can be fixed like this:

diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
index 22353bab76c8..f2b8891c7b36 100644
--- a/drivers/net/usb/pegasus.c
+++ b/drivers/net/usb/pegasus.c
@@ -459,6 +459,8 @@ static int enable_net_traffic(struct net_device *dev, struct usb_device *usb)

memcpy(pegasus->eth_regs, data, sizeof(data));
ret = set_registers(pegasus, EthCtrl0, 3, data);
+ if (ret < 0)
+ goto fail;

if (usb_dev_id[pegasus->dev_index].vendor == VENDOR_LINKSYS ||
usb_dev_id[pegasus->dev_index].vendor == VENDOR_LINKSYS2 ||


It was caused by our last refactoring: enable_net_traffic() now returns 0 on success and this ret is never checked.


With regards,
Pavel Skripkin