net/psp/psp_nl.c:513:13: sparse: sparse: cast removes address space '__rcu' of expression

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   bcc44b6785f216eb939226ade6e3910baa30516b
commit: 06c2dce2d0f69727144443664182052f56d1da35 psp: add new netlink cmd for dev-assoc and dev-disassoc
date:   8 weeks ago
config: riscv-randconfig-r131-20260807 (https://download.01.org/0day-ci/archive/20260808/[email protected]/config)
compiler: riscv64-linux-gcc (GCC) 8.5.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260808/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Fixes: 06c2dce2d0f6 ("psp: add new netlink cmd for dev-assoc and dev-disassoc")
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

sparse warnings: (new ones prefixed by >>)
>> net/psp/psp_nl.c:513:13: sparse: sparse: cast removes address space '__rcu' of expression

vim +/__rcu +513 net/psp/psp_nl.c

   475	
   476	int psp_nl_dev_assoc_doit(struct sk_buff *skb, struct genl_info *info)
   477	{
   478		struct psp_dev *psd = info->user_ptr[0];
   479		struct psp_assoc_dev *psp_assoc_dev;
   480		struct net_device *assoc_dev;
   481		struct sk_buff *rsp;
   482		u32 assoc_ifindex;
   483		struct net *net;
   484		int err;
   485	
   486		if (psd->assoc_dev_cnt >= PSP_ASSOC_DEV_MAX) {
   487			NL_SET_ERR_MSG(info->extack,
   488				       "Maximum number of associated devices reached");
   489			return -ENOSPC;
   490		}
   491	
   492		net = psp_nl_resolve_assoc_dev_ns(psd, info);
   493		if (IS_ERR(net))
   494			return PTR_ERR(net);
   495	
   496		psp_assoc_dev = kzalloc_obj(*psp_assoc_dev);
   497		if (!psp_assoc_dev) {
   498			err = -ENOMEM;
   499			goto err_put_net;
   500		}
   501	
   502		assoc_ifindex = nla_get_u32(info->attrs[PSP_A_DEV_IFINDEX]);
   503		assoc_dev = netdev_get_by_index(net, assoc_ifindex,
   504						&psp_assoc_dev->dev_tracker,
   505						GFP_KERNEL);
   506		if (!assoc_dev) {
   507			NL_SET_BAD_ATTR(info->extack, info->attrs[PSP_A_DEV_IFINDEX]);
   508			err = -ENODEV;
   509			goto err_free_assoc;
   510		}
   511	
   512		/* Check if device is already associated with a PSP device */
 > 513		if (cmpxchg(&assoc_dev->psp_dev, NULL, RCU_INITIALIZER(psd))) {
   514			NL_SET_ERR_MSG(info->extack,
   515				       "Device already associated with a PSP device");
   516			err = -EBUSY;
   517			goto err_put_dev;
   518		}
   519	
   520		psp_assoc_dev->assoc_dev = assoc_dev;
   521		rsp = psp_nl_reply_new(info);
   522		if (!rsp) {
   523			err = -ENOMEM;
   524			goto err_clean_ptr;
   525		}
   526	
   527		list_add_tail(&psp_assoc_dev->dev_list, &psd->assoc_dev_list);
   528		psd->assoc_dev_cnt++;
   529	
   530		put_net(net);
   531	
   532		psp_nl_notify_dev(psd, PSP_CMD_DEV_CHANGE_NTF);
   533	
   534		return psp_nl_reply_send(rsp, info);
   535	
   536	err_clean_ptr:
   537		rcu_assign_pointer(assoc_dev->psp_dev, NULL);
   538	err_put_dev:
   539		netdev_put(assoc_dev, &psp_assoc_dev->dev_tracker);
   540	err_free_assoc:
   541		kfree(psp_assoc_dev);
   542	err_put_net:
   543		put_net(net);
   544	
   545		return err;
   546	}
   547	

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki