Subject: Re: [PATCH net-next v6 3/6] net: devmem: prepare for autorelease rx token management

From: kernel test robot <[email-masked]>
Date: Thu, 6 Nov 2025 00:02:07 +0800

Hi Bobby,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 255d75ef029f33f75fcf5015052b7302486f7ad2]

url:    https://github.com/intel-lab-lkp/linux/commits/Bobby-Eshleman/net-devmem-rename-tx_vec-to-vec-in-dmabuf-binding/20251105-092703
base:   255d75ef029f33f75fcf5015052b7302486f7ad2
patch link:    https://lore.kernel.org/r/20251104-scratch-bobbyeshleman-devmem-tcp-token-upstream-v6-3-ea98cf4d40b3%40meta.com
patch subject: [PATCH net-next v6 3/6] net: devmem: prepare for autorelease rx token management
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20251105/[email-masked]/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251105/[email-masked]/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
| Reported-by: kernel test robot <[email-masked]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/

All warnings (new ones prefixed by >>):

>> net/core/sock.c:1107:12: warning: variable 'ret' is uninitialized when used here [-Wuninitialized]
    1107 |                                 return ret;
         |                                        ^~~
   net/core/sock.c:1095:9: note: initialize the variable 'ret' to silence this warning
    1095 |         int ret;
         |                ^
         |                 = 0
   1 warning generated.
--
>> net/ipv4/tcp.c:2626:6: warning: variable 'refs' is uninitialized when used here [-Wuninitialized]
    2626 |                                         refs++;
         |                                         ^~~~
   net/ipv4/tcp.c:2496:10: note: initialize the variable 'refs' to silence this warning
    2496 |         int refs;
         |                 ^
         |                  = 0
   1 warning generated.

vim +/ret +1107 net/core/sock.c

  1085	
  1086	static noinline_for_stack int
  1087	sock_devmem_dontneed_manual_release(struct sock *sk, struct dmabuf_token *tokens,
  1088					    unsigned int num_tokens)
  1089	{
  1090		struct net_iov *niov;
  1091		unsigned int i, j;
  1092		netmem_ref netmem;
  1093		unsigned int token;
  1094		int num_frags = 0;
  1095		int ret;
  1096	
  1097		if (!sk->sk_devmem_info.binding)
  1098			return -EINVAL;
  1099	
  1100		for (i = 0; i < num_tokens; i++) {
  1101			for (j = 0; j < tokens[i].token_count; j++) {
  1102				token = tokens[i].token_start + j;
  1103				if (token >= sk->sk_devmem_info.binding->dmabuf->size / PAGE_SIZE)
  1104					break;
  1105	
  1106				if (++num_frags > MAX_DONTNEED_FRAGS)
> 1107					return ret;
  1108	
  1109				niov = sk->sk_devmem_info.binding->vec[token];
  1110				if (atomic_dec_and_test(&niov->uref)) {
  1111					netmem = net_iov_to_netmem(niov);
  1112					WARN_ON_ONCE(!napi_pp_put_page(netmem));
  1113				}
  1114				ret++;
  1115			}
  1116		}
  1117	
  1118		atomic_sub(ret, &sk->sk_devmem_info.outstanding_urefs);
  1119	
  1120		return ret;
  1121	}
  1122	

-- 
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https://github.com/intel/lkp-tests/wiki