linux-kernel - drivers/md/dm-mpath.c:432 choose_pgpath() error: double unlocked 'm->lock' (orig line 402)

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Date:   Sat, 8 Aug 2020 18:07:17 +0800
From:   kernel test robot <lkp@...el.com>
To:     Mike Snitzer <snitzer@...hat.com>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: drivers/md/dm-mpath.c:432 choose_pgpath() error: double unlocked
 'm->lock' (orig line 402)

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   449dc8c97089a6e09fb2dac4d92b1b7ac0eb7c1e
commit: 69cea0d45a618ad4ae74f36386ef1af5128b2b19 dm mpath: changes from initial m->flags locking audit
date:   4 weeks ago
config: arm-randconfig-m031-20200808 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0

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

New smatch warnings:
drivers/md/dm-mpath.c:432 choose_pgpath() error: double unlocked 'm->lock' (orig line 402)

Old smatch warnings:
drivers/md/dm-mpath.c:443 choose_pgpath() error: double unlocked 'm->lock' (orig line 389)
drivers/md/dm-mpath.c:593 __map_bio() error: double unlocked 'm->lock' (orig line 589)
drivers/md/dm-mpath.c:1574 pg_init_done() error: double unlocked 'm->lock' (orig line 1527)

vim +432 drivers/md/dm-mpath.c

   378	
   379	static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
   380	{
   381		unsigned long flags;
   382		struct priority_group *pg;
   383		struct pgpath *pgpath;
   384		unsigned bypassed = 1;
   385	
   386		if (!atomic_read(&m->nr_valid_paths)) {
   387			spin_lock_irqsave(&m->lock, flags);
   388			clear_bit(MPATHF_QUEUE_IO, &m->flags);
   389			spin_unlock_irqrestore(&m->lock, flags);
   390			goto failed;
   391		}
   392	
   393		/* Were we instructed to switch PG? */
   394		if (READ_ONCE(m->next_pg)) {
   395			spin_lock_irqsave(&m->lock, flags);
   396			pg = m->next_pg;
   397			if (!pg) {
   398				spin_unlock_irqrestore(&m->lock, flags);
   399				goto check_current_pg;
   400			}
   401			m->next_pg = NULL;
 > 402			spin_unlock_irqrestore(&m->lock, flags);
   403			pgpath = choose_path_in_pg(m, pg, nr_bytes);
   404			if (!IS_ERR_OR_NULL(pgpath))
   405				return pgpath;
   406		}
   407	
   408		/* Don't change PG until it has no remaining paths */
   409	check_current_pg:
   410		pg = READ_ONCE(m->current_pg);
   411		if (pg) {
   412			pgpath = choose_path_in_pg(m, pg, nr_bytes);
   413			if (!IS_ERR_OR_NULL(pgpath))
   414				return pgpath;
   415		}
   416	
   417		/*
   418		 * Loop through priority groups until we find a valid path.
   419		 * First time we skip PGs marked 'bypassed'.
   420		 * Second time we only try the ones we skipped, but set
   421		 * pg_init_delay_retry so we do not hammer controllers.
   422		 */
   423		do {
   424			list_for_each_entry(pg, &m->priority_groups, list) {
   425				if (pg->bypassed == !!bypassed)
   426					continue;
   427				pgpath = choose_path_in_pg(m, pg, nr_bytes);
   428				if (!IS_ERR_OR_NULL(pgpath)) {
   429					if (!bypassed) {
   430						spin_lock_irqsave(&m->lock, flags);
   431						set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
 > 432						spin_unlock_irqrestore(&m->lock, flags);
   433					}
   434					return pgpath;
   435				}
   436			}
   437		} while (bypassed--);
   438	
   439	failed:
   440		spin_lock_irqsave(&m->lock, flags);
   441		m->current_pgpath = NULL;
   442		m->current_pg = NULL;
   443		spin_unlock_irqrestore(&m->lock, flags);
   444	
   445		return NULL;
   446	}
   447	

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

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