Hi Dan, Thanks for your hints, see the comment in lines. On Tue, Jun 26, 2018 at 3:44 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > [ There is a bug with kbuild where it's not showing the Smatch warnings > but I can probably guess... - dan ] > > Hi Pingfan, > > Thank you for the patch! Perhaps something to improve: > > url: https://github.com/0day-ci/linux/commits/Pingfan-Liu/drivers-base-bugfix-for-supplier-consumer-ordering-in-device_kset/20180625-132702 > > > # https://github.com/0day-ci/linux/commit/1b2a1e63898baf80e8e830991284e1534bc54766 > git remote add linux-review https://github.com/0day-ci/linux > git remote update linux-review > git checkout 1b2a1e63898baf80e8e830991284e1534bc54766 > vim +/ret +245 drivers/base/core.c > > 1b2a1e63 Pingfan Liu 2018-06-25 216 > 1b2a1e63 Pingfan Liu 2018-06-25 217 /* When reodering, take care of the range of (old_pos(dev), new_pos(dev)), > 1b2a1e63 Pingfan Liu 2018-06-25 218 * there may be requirement to recursively move item. > 1b2a1e63 Pingfan Liu 2018-06-25 219 */ > 1b2a1e63 Pingfan Liu 2018-06-25 220 int device_reorder_consumer(struct device *dev) > 1b2a1e63 Pingfan Liu 2018-06-25 221 { > 1b2a1e63 Pingfan Liu 2018-06-25 222 struct list_head *iter, *left, *right; > 1b2a1e63 Pingfan Liu 2018-06-25 223 struct device *cur_dev; > 1b2a1e63 Pingfan Liu 2018-06-25 224 struct pos_info info; > 1b2a1e63 Pingfan Liu 2018-06-25 225 int ret, idx; > 1b2a1e63 Pingfan Liu 2018-06-25 226 > 1b2a1e63 Pingfan Liu 2018-06-25 227 idx = device_links_read_lock(); > 1b2a1e63 Pingfan Liu 2018-06-25 228 if (list_empty(&dev->links.suppliers)) { > 1b2a1e63 Pingfan Liu 2018-06-25 229 device_links_read_unlock(idx); > 1b2a1e63 Pingfan Liu 2018-06-25 230 return 0; > 1b2a1e63 Pingfan Liu 2018-06-25 231 } > 1b2a1e63 Pingfan Liu 2018-06-25 232 spin_lock(&devices_kset->list_lock); > 1b2a1e63 Pingfan Liu 2018-06-25 233 list_for_each_prev(iter, &devices_kset->list) { > 1b2a1e63 Pingfan Liu 2018-06-25 234 cur_dev = list_entry(iter, struct device, kobj.entry); > 1b2a1e63 Pingfan Liu 2018-06-25 235 ret = find_last_supplier(dev, cur_dev); > 1b2a1e63 Pingfan Liu 2018-06-25 236 switch (ret) { > 1b2a1e63 Pingfan Liu 2018-06-25 237 case -1: > 1b2a1e63 Pingfan Liu 2018-06-25 238 goto unlock; > 1b2a1e63 Pingfan Liu 2018-06-25 239 case 1: > 1b2a1e63 Pingfan Liu 2018-06-25 240 break; > 1b2a1e63 Pingfan Liu 2018-06-25 241 case 0: > 1b2a1e63 Pingfan Liu 2018-06-25 242 continue; > > The break breaks from the switch and the continue continues the loop so > they're equivalent. Perhaps you intended to break from the loop? > Yes, you are right. > 1b2a1e63 Pingfan Liu 2018-06-25 243 } > 1b2a1e63 Pingfan Liu 2018-06-25 244 } > 1b2a1e63 Pingfan Liu 2018-06-25 @245 BUG_ON(!ret); > > If the list is empty then "ret" can be unitialized. We test a different > list "dev->links.suppliers" to see if that's empty. I wrote a bunch of > code to make Smatch try to understand about empty lists, but I don't > think it works... > Yes, if list_empty, then the code can not touch ret. But ret is useless in this scene. Does it matter? Thanks and regards, Pingfan > 1b2a1e63 Pingfan Liu 2018-06-25 246 > 1b2a1e63 Pingfan Liu 2018-06-25 247 /* record the affected open section */ > 1b2a1e63 Pingfan Liu 2018-06-25 248 left = dev->kobj.entry.prev; > 1b2a1e63 Pingfan Liu 2018-06-25 249 right = iter; > 1b2a1e63 Pingfan Liu 2018-06-25 250 info.pos = list_entry(iter, struct device, kobj.entry); > 1b2a1e63 Pingfan Liu 2018-06-25 251 info.tail = NULL; > 1b2a1e63 Pingfan Liu 2018-06-25 252 /* dry out the consumers in (left,right) */ > 1b2a1e63 Pingfan Liu 2018-06-25 253 __device_reorder_consumer(dev, left, right, &info); > 1b2a1e63 Pingfan Liu 2018-06-25 254 > 1b2a1e63 Pingfan Liu 2018-06-25 255 unlock: > 1b2a1e63 Pingfan Liu 2018-06-25 256 spin_unlock(&devices_kset->list_lock); > 1b2a1e63 Pingfan Liu 2018-06-25 257 device_links_read_unlock(idx); > 1b2a1e63 Pingfan Liu 2018-06-25 258 return 0; > 1b2a1e63 Pingfan Liu 2018-06-25 259 } > 1b2a1e63 Pingfan Liu 2018-06-25 260 > > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://lists.01.org/pipermail/kbuild-all Intel Corporation
