[android-common:android-4.19-stable 2/2] kernel/jump_label.c:207:5-24: atomic_dec_and_test variation before object free at line 210.

[android-common:android-4.19-stable 2/2] kernel/jump_label.c:207:5-24: atomic_dec_and_test variation before object free at line 210.

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
TO: cros-kernel-buildreports(a)googlegroups.com

tree:   https://android.googlesource.com/kernel/common android-4.19-stable
head:   e90dc48804e35af100f5a6f435c388d859dfd78f
commit: e90dc48804e35af100f5a6f435c388d859dfd78f [2/2] UPSTREAM: locking/static_key: Fix false positive warnings on concurrent dec/inc
:::::: branch date: 20 hours ago
:::::: commit date: 20 hours ago
config: arm64-randconfig-c003-20210226 (attached as .config)
compiler: aarch64-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>


"coccinelle warnings: (new ones prefixed by >>)"
>> kernel/jump_label.c:207:5-24: atomic_dec_and_test variation before object free at line 210.

vim +207 kernel/jump_label.c

1dbb6704de91b1 Paolo Bonzini  2017-08-01  184  
ce48c146495a1a Peter Zijlstra 2018-01-22  185  static void __static_key_slow_dec_cpuslocked(struct static_key *key,
8b7b412807053a Marc Zyngier   2017-08-01  186  					   unsigned long rate_limit,
8b7b412807053a Marc Zyngier   2017-08-01  187  					   struct delayed_work *work)
bf5438fca2950b Jason Baron    2010-09-17  188  {
e90dc48804e35a Peter Zijlstra 2019-03-19  189  	int val;
e90dc48804e35a Peter Zijlstra 2019-03-19  190  
549a2d6034b5dd Peter Zijlstra 2018-07-31  191  	lockdep_assert_cpus_held();
549a2d6034b5dd Peter Zijlstra 2018-07-31  192  
4c5ea0a9cd02d6 Paolo Bonzini  2016-06-21  193  	/*
4c5ea0a9cd02d6 Paolo Bonzini  2016-06-21  194  	 * The negative count check is valid even when a negative
4c5ea0a9cd02d6 Paolo Bonzini  2016-06-21  195  	 * key->enabled is in use by static_key_slow_inc(); a
4c5ea0a9cd02d6 Paolo Bonzini  2016-06-21  196  	 * __static_key_slow_dec() before the first static_key_slow_inc()
4c5ea0a9cd02d6 Paolo Bonzini  2016-06-21  197  	 * returns is unbalanced, because all other static_key_slow_inc()
4c5ea0a9cd02d6 Paolo Bonzini  2016-06-21  198  	 * instances block while the update is in progress.
4c5ea0a9cd02d6 Paolo Bonzini  2016-06-21  199  	 */
e90dc48804e35a Peter Zijlstra 2019-03-19  200  	val = atomic_fetch_add_unless(&key->enabled, -1, 1);
e90dc48804e35a Peter Zijlstra 2019-03-19  201  	if (val != 1) {
e90dc48804e35a Peter Zijlstra 2019-03-19  202  		WARN(val < 0, "jump label: negative count!\n");
d430d3d7e646eb Jason Baron    2011-03-16  203  		return;
fadf0464b83f91 Jason Baron    2012-02-21  204  	}
bf5438fca2950b Jason Baron    2010-09-17  205  
e90dc48804e35a Peter Zijlstra 2019-03-19  206  	jump_label_lock();
e90dc48804e35a Peter Zijlstra 2019-03-19 @207  	if (atomic_dec_and_test(&key->enabled)) {
b202952075f626 Gleb Natapov   2011-11-27  208  		if (rate_limit) {
b202952075f626 Gleb Natapov   2011-11-27  209  			atomic_inc(&key->enabled);
b202952075f626 Gleb Natapov   2011-11-27 @210  			schedule_delayed_work(work, rate_limit);
c5905afb0ee655 Ingo Molnar    2012-02-24  211  		} else {
706249c222f684 Peter Zijlstra 2015-07-24  212  			jump_label_update(key);
c5905afb0ee655 Ingo Molnar    2012-02-24  213  		}
e90dc48804e35a Peter Zijlstra 2019-03-19  214  	}
91bad2f8d30574 Jason Baron    2010-10-01  215  	jump_label_unlock();
8b7b412807053a Marc Zyngier   2017-08-01  216  }
8b7b412807053a Marc Zyngier   2017-08-01  217  

---
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