Hello Coly Li,
Commit 3ea3354cb9f0 ("badblocks: improve badblocks_check() for
multiple ranges handling") from Aug 12, 2023 (linux-next), leads to
the following Smatch static checker warning:
block/badblocks.c:1251 _badblocks_check()
warn: unsigned 'sectors' is never less than zero.
block/badblocks.c
1186 static int _badblocks_check(struct badblocks *bb, sector_t s, sector_t sectors,
^^^^^^^^^^^^^^^^
sector_t is u64.
1187 sector_t *first_bad, sector_t *bad_sectors)
1188 {
1189 int prev = -1, hint = -1, set = 0;
1190 struct badblocks_context bad;
1191 int unacked_badblocks = 0;
1192 int acked_badblocks = 0;
1193 u64 *p = bb->page;
1194 int len, rv;
1195
1196 re_check:
1197 bad.start = s;
1198 bad.len = sectors;
1199
1200 if (badblocks_empty(bb)) {
1201 len = sectors;
1202 goto update_sectors;
1203 }
1204
1205 prev = prev_badblocks(bb, &bad, hint);
1206
1207 /* start after all badblocks */
1208 if ((prev >= 0) &&
1209 ((prev + 1) >= bb->count) && !overlap_front(bb, prev, &bad)) {
1210 len = sectors;
1211 goto update_sectors;
1212 }
1213
1214 /* Overlapped with front badblocks record */
1215 if ((prev >= 0) && overlap_front(bb, prev, &bad)) {
1216 if (BB_ACK(p[prev]))
1217 acked_badblocks++;
1218 else
1219 unacked_badblocks++;
1220
1221 if (BB_END(p[prev]) >= (s + sectors))
1222 len = sectors;
1223 else
1224 len = BB_END(p[prev]) - s;
1225
1226 if (set == 0) {
1227 *first_bad = BB_OFFSET(p[prev]);
1228 *bad_sectors = BB_LEN(p[prev]);
1229 set = 1;
1230 }
1231 goto update_sectors;
1232 }
1233
1234 /* Not front overlap, but behind overlap */
1235 if ((prev + 1) < bb->count && overlap_behind(bb, &bad, prev + 1)) {
1236 len = BB_OFFSET(p[prev + 1]) - bad.start;
1237 hint = prev + 1;
1238 goto update_sectors;
1239 }
1240
1241 /* not cover any badblocks range in the table */
1242 len = sectors;
1243
1244 update_sectors:
1245 s += len;
1246 sectors -= len;
^^^^^^^^^^^^^^
Subtraction.
1247
1248 if (sectors > 0)
1249 goto re_check;
1250
--> 1251 WARN_ON(sectors < 0);
^^^^^^^^^^^
1252
1253 if (unacked_badblocks > 0)
1254 rv = -1;
1255 else if (acked_badblocks > 0)
1256 rv = 1;
1257 else
1258 rv = 0;
1259
1260 return rv;
1261 }
regards,
dan carpenter
