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SubjectRe: [PATCH bpf-next v4 1/4] bpf: Generalize bpf_sk_storage
Hi KP,

I love your patch! Perhaps something to improve:

[auto build test WARNING on bpf-next/master]

url: https://github.com/0day-ci/linux/commits/KP-Singh/Generalizing-bpf_local_storage/20200709-181906
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: s390-randconfig-s032-20200719 (attached as .config)
compiler: s390-linux-gcc (GCC) 9.3.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.2-49-g707c5017-dirty
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=s390

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


sparse warnings: (new ones prefixed by >>)

>> kernel/bpf/bpf_local_storage.c:237:16: sparse: sparse: non size-preserving integer to pointer cast

vim +237 kernel/bpf/bpf_local_storage.c

221
222 /* Publish local_storage to the address. This is used because we are already
223 * in a region where we cannot grab a lock on the object owning the storage (
224 * (e.g sk->sk_lock). Hence, atomic ops is used.
225 *
226 * From now on, the addr pointer is protected
227 * by the local_storage->lock. Hence, upon freeing,
228 * the local_storage->lock must be held before unlinking the storage from the
229 * owner.
230 */
231 int bpf_local_storage_publish(struct bpf_local_storage_elem *first_selem,
232 struct bpf_local_storage **addr,
233 struct bpf_local_storage *curr)
234 {
235 struct bpf_local_storage *prev;
236
> 237 prev = cmpxchg(addr, NULL, curr);
238 if (unlikely(prev)) {
239 /* Note that even first_selem was linked to smap's
240 * bucket->list, first_selem can be freed immediately
241 * (instead of kfree_rcu) because
242 * bpf_local_storage_map_free() does a
243 * synchronize_rcu() before walking the bucket->list.
244 * Hence, no one is accessing selem from the
245 * bucket->list under rcu_read_lock().
246 */
247 bpf_selem_unlink_map(first_selem);
248 return -EAGAIN;
249 }
250
251 return 0;
252 }
253

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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