Hello Hannes Reinecke,
The patch a99e0ceaa832: "dm zoned: per-device reclaim" from Jun 2,
2020, leads to the following static checker warning:
drivers/md/dm-zoned-reclaim.c:428 dmz_do_reclaim()
error: potentially dereferencing uninitialized 'rzone'.
drivers/md/dm-zoned-reclaim.c
364 static int dmz_do_reclaim(struct dmz_reclaim *zrc)
365 {
366 struct dmz_metadata *zmd = zrc->metadata;
367 struct dm_zone *dzone;
368 struct dm_zone *rzone;
^^^^^
369 unsigned long start;
370 int ret;
371
372 /* Get a data zone */
373 dzone = dmz_get_zone_for_reclaim(zmd, zrc->dev_idx,
374 dmz_target_idle(zrc));
375 if (!dzone) {
376 DMDEBUG("(%s/%u): No zone found to reclaim",
377 dmz_metadata_label(zmd), zrc->dev_idx);
378 return -EBUSY;
379 }
380
381 start = jiffies;
382 if (dmz_is_cache(dzone) || dmz_is_rnd(dzone)) {
383 if (!dmz_weight(dzone)) {
384 /* Empty zone */
385 dmz_reclaim_empty(zrc, dzone);
386 ret = 0;
387 } else {
388 /*
389 * Reclaim the random data zone by moving its
390 * valid data blocks to a free sequential zone.
391 */
392 ret = dmz_reclaim_rnd_data(zrc, dzone);
393 }
394 rzone = dzone;
395
396 } else {
397 struct dm_zone *bzone = dzone->bzone;
398 sector_t chunk_block = 0;
399
400 ret = dmz_first_valid_block(zmd, bzone, &chunk_block);
401 if (ret < 0)
402 goto out;
"rzone" is uninitialized if "ret < 0".
403
404 if (ret == 0 || chunk_block >= dzone->wp_block) {
405 /*
406 * The buffer zone is empty or its valid blocks are
407 * after the data zone write pointer.
408 */
409 ret = dmz_reclaim_buf(zrc, dzone);
410 rzone = bzone;
411 } else {
412 /*
413 * Reclaim the data zone by merging it into the
414 * buffer zone so that the buffer zone itself can
415 * be later reclaimed.
416 */
417 ret = dmz_reclaim_seq_data(zrc, dzone);
418 rzone = dzone;
419 }
420 }
421 out:
422 if (ret) {
423 if (ret == -EINTR)
424 DMDEBUG("(%s/%u): reclaim zone %u interrupted",
425 dmz_metadata_label(zmd), zrc->dev_idx,
426 rzone->id);
427 else
428 DMDEBUG("(%s/%u): Failed to reclaim zone %u, err %d",
429 dmz_metadata_label(zmd), zrc->dev_idx,
430 rzone->id, ret);
^^^^^^^^^
Dereference.
431 dmz_unlock_zone_reclaim(dzone);
432 return ret;
433 }
434
435 ret = dmz_flush_metadata(zrc->metadata);
436 if (ret) {
437 DMDEBUG("(%s/%u): Metadata flush for zone %u failed, err %d",
438 dmz_metadata_label(zmd), zrc->dev_idx, rzone->id, ret);
439 return ret;
440 }
441
442 DMDEBUG("(%s/%u): Reclaimed zone %u in %u ms",
443 dmz_metadata_label(zmd), zrc->dev_idx,
444 rzone->id, jiffies_to_msecs(jiffies - start));
445 return 0;
446 }
regards,
dan carpenter
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