linux-kernel - [netfilter-nf-next:testing 9/12] net/netfilter/core.c:130:26: warning: variable 'hook_bpf

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Message-ID: <202205200503.Y3uqHqTF-lkp@intel.com>
Date:   Fri, 20 May 2022 05:42:03 +0800
From:   kernel test robot <lkp@...el.com>
To:     Florian Westphal <fw@...len.de>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [netfilter-nf-next:testing 9/12] net/netfilter/core.c:130:26:
 warning: variable 'hook_bpf_prog' set but not used

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next.git testing
head:   4456ac35299c131e2ac26b4dc025b257d810277b
commit: 11b2910d788799e8c68df305994260fd79a61e10 [9/12] netfilter: add bpf base hook program generator
config: alpha-defconfig (https://download.01.org/0day-ci/archive/20220520/202205200503.Y3uqHqTF-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 11.3.0
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://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next.git/commit/?id=11b2910d788799e8c68df305994260fd79a61e10
        git remote add netfilter-nf-next git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next.git
        git fetch --no-tags netfilter-nf-next testing
        git checkout 11b2910d788799e8c68df305994260fd79a61e10
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=alpha SHELL=/bin/bash net/netfilter/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   net/netfilter/core.c: In function 'nf_hook_entries_grow':
>> net/netfilter/core.c:130:26: warning: variable 'hook_bpf_prog' set but not used [-Wunused-but-set-variable]
     130 |         struct bpf_prog *hook_bpf_prog;
         |                          ^~~~~~~~~~~~~
   net/netfilter/core.c: In function '__nf_hook_entries_try_shrink':
   net/netfilter/core.c:269:26: warning: unused variable 'hook_bpf_prog' [-Wunused-variable]
     269 |         struct bpf_prog *hook_bpf_prog = NULL;
         |                          ^~~~~~~~~~~~~


vim +/hook_bpf_prog +130 net/netfilter/core.c

   123	
   124	static struct nf_hook_entries *
   125	nf_hook_entries_grow(const struct nf_hook_entries *old,
   126			     const struct nf_hook_ops *reg)
   127	{
   128		unsigned int i, alloc_entries, nhooks, old_entries;
   129		struct nf_hook_ops **orig_ops = NULL;
 > 130		struct bpf_prog *hook_bpf_prog;
   131		struct nf_hook_ops **new_ops;
   132		struct nf_hook_entries *new;
   133		bool inserted = false;
   134	
   135		alloc_entries = 1;
   136		old_entries = old ? old->num_hook_entries : 0;
   137	
   138		if (old) {
   139			orig_ops = nf_hook_entries_get_hook_ops(old);
   140	
   141			for (i = 0; i < old_entries; i++) {
   142				if (orig_ops[i] != &dummy_ops)
   143					alloc_entries++;
   144			}
   145		}
   146	
   147		if (alloc_entries > MAX_HOOK_COUNT)
   148			return ERR_PTR(-E2BIG);
   149	
   150		new = allocate_hook_entries_size(alloc_entries);
   151		if (!new)
   152			return ERR_PTR(-ENOMEM);
   153	
   154		new_ops = nf_hook_entries_get_hook_ops(new);
   155	
   156		i = 0;
   157		nhooks = 0;
   158		while (i < old_entries) {
   159			if (orig_ops[i] == &dummy_ops) {
   160				++i;
   161				continue;
   162			}
   163	
   164			if (inserted || reg->priority > orig_ops[i]->priority) {
   165				new_ops[nhooks] = (void *)orig_ops[i];
   166				new->hooks[nhooks] = old->hooks[i];
   167				i++;
   168			} else {
   169				new_ops[nhooks] = (void *)reg;
   170				new->hooks[nhooks].hook = reg->hook;
   171				new->hooks[nhooks].priv = reg->priv;
   172				inserted = true;
   173			}
   174			nhooks++;
   175		}
   176	
   177		if (!inserted) {
   178			new_ops[nhooks] = (void *)reg;
   179			new->hooks[nhooks].hook = reg->hook;
   180			new->hooks[nhooks].priv = reg->priv;
   181		}
   182	
   183		hook_bpf_prog = nf_hook_bpf_create(new);
   184	
   185		/* allocate_hook_entries_size() pre-inits ->hook_prog
   186		 * to a fallback program that calls nf_hook_slow().
   187		 *
   188		 * Alternatively we could have nf_hook_entries_grow()
   189		 * return an error here.
   190		 */
   191	#if IS_ENABLED(CONFIG_NF_HOOK_BPF)
   192		if (hook_bpf_prog) {
   193			struct bpf_prog *old_prog = NULL;
   194	
   195			new->hook_prog = hook_bpf_prog;
   196	
   197			if (old)
   198				old_prog = old->hook_prog;
   199	
   200			nf_hook_bpf_change_prog(BPF_DISPATCHER_PTR(nf_hook_base),
   201						old_prog, hook_bpf_prog);
   202		}
   203	#endif
   204		return new;
   205	}
   206	

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