[netfilter-nf-next:testing 9/12] net/netfilter/core.c:130:26: warning: variable 'hook_bpf_prog' set but not used

From: kernel test robot
Date: Thu May 19 2022 - 17:54:46 EST

Next message: kernel test robot: "[paulmck-rcu:context-tracking.2022.05.19a 20/21] kernel/context_tracking.c:500:4: error: call to undeclared function 'ct_kernel_exit'; ISO C99 and later do not support implicit function declarations"
Previous message: kernel test robot: "[netfilter-nf-next:testing 9/12] ld.lld: error: undefined symbol: nf_hook_bpf_create"
In reply to: kernel test robot: "[netfilter-nf-next:testing 9/12] net/netfilter/core.c:130:26: warning: variable 'hook_bpf_prog' set but not used"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

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: i386-randconfig-a005 (https://download.01.org/0day-ci/archive/20220520/202205200540.Em86BBF9-lkp@xxxxxxxxx/config)
compiler: gcc-11 (Debian 11.3.0-1) 11.3.0
reproduce (this is a W=1 build):
# 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
make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash net/netfilter/

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

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
207 static void hooks_validate(const struct nf_hook_entries *hooks)
208 {
209 #ifdef CONFIG_DEBUG_MISC
210 struct nf_hook_ops **orig_ops;
211 int prio = INT_MIN;
212 size_t i = 0;
213
214 orig_ops = nf_hook_entries_get_hook_ops(hooks);
215
216 for (i = 0; i < hooks->num_hook_entries; i++) {
217 if (orig_ops[i] == &dummy_ops)
218 continue;
219
220 WARN_ON(orig_ops[i]->priority < prio);
221
222 if (orig_ops[i]->priority > prio)
223 prio = orig_ops[i]->priority;
224 }
225 #endif
226 }
227
228 int nf_hook_entries_insert_raw(struct nf_hook_entries __rcu **pp,
229 const struct nf_hook_ops *reg)
230 {
231 struct nf_hook_entries *new_hooks;
232 struct nf_hook_entries *p;
233
234 p = rcu_dereference_raw(*pp);
235 new_hooks = nf_hook_entries_grow(p, reg);
236 if (IS_ERR(new_hooks))
237 return PTR_ERR(new_hooks);
238
239 hooks_validate(new_hooks);
240
241 rcu_assign_pointer(*pp, new_hooks);
242
243 BUG_ON(p == new_hooks);
244 nf_hook_entries_free(p);
245 return 0;
246 }
247 EXPORT_SYMBOL_GPL(nf_hook_entries_insert_raw);
248
249 /*
250 * __nf_hook_entries_try_shrink - try to shrink hook array
251 *
252 * @old -- current hook blob at @pp
253 * @pp -- location of hook blob
254 *
255 * Hook unregistration must always succeed, so to-be-removed hooks
256 * are replaced by a dummy one that will just move to next hook.
257 *
258 * This counts the current dummy hooks, attempts to allocate new blob,
259 * copies the live hooks, then replaces and discards old one.
260 *
261 * return values:
262 *
263 * Returns address to free, or NULL.
264 */
265 static void *__nf_hook_entries_try_shrink(struct nf_hook_entries *old,
266 struct nf_hook_entries __rcu **pp)
267 {
268 unsigned int i, j, skip = 0, hook_entries;
> 269 struct bpf_prog *hook_bpf_prog = NULL;
270 struct nf_hook_entries *new = NULL;
271 struct nf_hook_ops **orig_ops;
272 struct nf_hook_ops **new_ops;
273
274 if (WARN_ON_ONCE(!old))
275 return NULL;
276
277 orig_ops = nf_hook_entries_get_hook_ops(old);
278 for (i = 0; i < old->num_hook_entries; i++) {
279 if (orig_ops[i] == &dummy_ops)
280 skip++;
281 }
282
283 /* if skip == hook_entries all hooks have been removed */
284 hook_entries = old->num_hook_entries;
285 if (skip == hook_entries)
286 goto out_assign;
287
288 if (skip == 0)
289 return NULL;
290
291 hook_entries -= skip;
292 new = allocate_hook_entries_size(hook_entries);
293 if (!new) {
294 #if IS_ENABLED(CONFIG_NF_HOOK_BPF)
295 struct bpf_prog *old_prog = old->hook_prog;
296
297 WRITE_ONCE(old->hook_prog, fallback_nf_hook_slow);
298 nf_hook_bpf_change_prog(BPF_DISPATCHER_PTR(nf_hook_base), old_prog, NULL);
299 #endif
300 return NULL;
301 }
302
303 new_ops = nf_hook_entries_get_hook_ops(new);
304 for (i = 0, j = 0; i < old->num_hook_entries; i++) {
305 if (orig_ops[i] == &dummy_ops)
306 continue;
307 new->hooks[j] = old->hooks[i];
308 new_ops[j] = (void *)orig_ops[i];
309 j++;
310 }
311 hooks_validate(new);
312

--
0-DAY CI Kernel Test Service
https://01.org/lkp