linux-kernel - [paulmck-rcu:dev.2023.08.22a 63/69] kernel/locking/locktorture.c:294:20-23: ERROR: t is NULL but dereferenced. (fwd)

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Message-ID: <e24280d0-dfbb-f4f-64aa-9f50268450b@inria.fr>
Date:   Thu, 31 Aug 2023 11:01:02 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     "Paul E. McKenney" <paulmck@...nel.org>
cc:     linux-kernel@...r.kernel.org, oe-kbuild-all@...ts.linux.dev
Subject: [paulmck-rcu:dev.2023.08.22a 63/69] kernel/locking/locktorture.c:294:20-23:
 ERROR: t is NULL but dereferenced. (fwd)

Maybe a ! has been forgotton on line 290?

julia

---------- Forwarded message ----------
Date: Thu, 31 Aug 2023 10:46:56 +0800
From: kernel test robot <lkp@...el.com>
To: oe-kbuild@...ts.linux.dev
Cc: lkp@...el.com, Julia Lawall <julia.lawall@...ia.fr>
Subject: [paulmck-rcu:dev.2023.08.22a 63/69]
    kernel/locking/locktorture.c:294:20-23: ERROR: t is NULL but dereferenced.

BCC: lkp@...el.com
CC: oe-kbuild-all@...ts.linux.dev
CC: linux-kernel@...r.kernel.org
TO: "Paul E. McKenney" <paulmck@...nel.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2023.08.22a
head:   354957ec11dc80eac68c4b1e10c237d69adc1833
commit: 758918804e0d5216981df3cef99ffd7ba0842192 [63/69] locktorture: Add indication of task write-holding lock
:::::: branch date: 6 days ago
:::::: commit date: 7 days ago
config: i386-randconfig-053-20230831 (https://download.01.org/0day-ci/archive/20230831/202308311022.j7jKnIdL-lkp@intel.com/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce: (https://download.01.org/0day-ci/archive/20230831/202308311022.j7jKnIdL-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Reported-by: Julia Lawall <julia.lawall@...ia.fr>
| Closes: https://lore.kernel.org/r/202308311022.j7jKnIdL-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> kernel/locking/locktorture.c:294:20-23: ERROR: t is NULL but dereferenced.
   kernel/locking/locktorture.c:294:43-47: ERROR: t is NULL but dereferenced.

vim +294 kernel/locking/locktorture.c

bdd8d60bd4047a Paul E. McKenney 2023-08-23  284
94a8fb5e4673d7 Paul E. McKenney 2023-08-22  285  static int torture_spin_lock_dump(struct notifier_block *nb, unsigned long v, void *ptr)
94a8fb5e4673d7 Paul E. McKenney 2023-08-22  286  {
758918804e0d52 Paul E. McKenney 2023-08-23  287  	struct task_struct *t = READ_ONCE(lock_is_write_held);
758918804e0d52 Paul E. McKenney 2023-08-23  288
94a8fb5e4673d7 Paul E. McKenney 2023-08-22  289  	pr_alert("%s invoked: v=%lu, duration=%lu.\n", __func__, v, (unsigned long)ptr);
758918804e0d52 Paul E. McKenney 2023-08-23  290  	if (t) {
758918804e0d52 Paul E. McKenney 2023-08-23  291  		pr_alert("%s No task holding lock.\n", __func__);
758918804e0d52 Paul E. McKenney 2023-08-23  292  	} else {
758918804e0d52 Paul E. McKenney 2023-08-23  293  		pr_alert("%s Lock held by task %ps %d %*s\n",
758918804e0d52 Paul E. McKenney 2023-08-23 @294  			 __func__, t, t->pid, TASK_COMM_LEN, t->comm);
758918804e0d52 Paul E. McKenney 2023-08-23  295  		sched_show_task(t);
758918804e0d52 Paul E. McKenney 2023-08-23  296  	}
bdd8d60bd4047a Paul E. McKenney 2023-08-23  297  	spinlock_dump(&torture_spinlock, true);
94a8fb5e4673d7 Paul E. McKenney 2023-08-22  298  	return NOTIFY_OK;
94a8fb5e4673d7 Paul E. McKenney 2023-08-22  299  }
94a8fb5e4673d7 Paul E. McKenney 2023-08-22  300

-- 
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https://github.com/intel/lkp-tests/wiki