Subject: Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state

From: kernel test robot <[email-masked]>
Date: Fri, 24 Jul 2020 11:15:02 +0800

Hi Nicholas,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linux/master]
[also build test WARNING on powerpc/next linus/master v5.8-rc6 next-20200723]
[cannot apply to tip/locking/core]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Nicholas-Piggin/lockdep-improve-current-hard-soft-irqs_enabled-synchronisation-with-actual-irq-state/20200723-185938
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 9ebcfadb0610322ac537dd7aa5d9cbc2b2894c68
config: i386-randconfig-s001-20200723 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-14) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.2-93-g4c6cbe55-dirty
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email-masked]>

sparse warnings: (new ones prefixed by >>)

   kernel/locking/spinlock.c:149:17: sparse: sparse: context imbalance in '_raw_spin_lock' - wrong count at exit
   kernel/locking/spinlock.c: note: in included file (through include/linux/preempt.h):
>> arch/x86/include/asm/preempt.h:79:9: sparse: sparse: context imbalance in '_raw_spin_lock_irqsave' - wrong count at exit
>> arch/x86/include/asm/preempt.h:79:9: sparse: sparse: context imbalance in '_raw_spin_lock_irq' - wrong count at exit
   kernel/locking/spinlock.c:173:17: sparse: sparse: context imbalance in '_raw_spin_lock_bh' - wrong count at exit
   kernel/locking/spinlock.c:181:17: sparse: sparse: context imbalance in '_raw_spin_unlock' - unexpected unlock
   kernel/locking/spinlock.c:189:17: sparse: sparse: context imbalance in '_raw_spin_unlock_irqrestore' - unexpected unlock
   kernel/locking/spinlock.c:197:17: sparse: sparse: context imbalance in '_raw_spin_unlock_irq' - unexpected unlock
   kernel/locking/spinlock.c:205:17: sparse: sparse: context imbalance in '_raw_spin_unlock_bh' - unexpected unlock
   kernel/locking/spinlock.c:221:17: sparse: sparse: context imbalance in '_raw_read_lock' - wrong count at exit
>> arch/x86/include/asm/preempt.h:79:9: sparse: sparse: context imbalance in '_raw_read_lock_irqsave' - wrong count at exit
>> arch/x86/include/asm/preempt.h:79:9: sparse: sparse: context imbalance in '_raw_read_lock_irq' - wrong count at exit
   kernel/locking/spinlock.c:245:17: sparse: sparse: context imbalance in '_raw_read_lock_bh' - wrong count at exit
   kernel/locking/spinlock.c:253:17: sparse: sparse: context imbalance in '_raw_read_unlock' - unexpected unlock
   kernel/locking/spinlock.c:261:17: sparse: sparse: context imbalance in '_raw_read_unlock_irqrestore' - unexpected unlock
   kernel/locking/spinlock.c:269:17: sparse: sparse: context imbalance in '_raw_read_unlock_irq' - unexpected unlock
   kernel/locking/spinlock.c:277:17: sparse: sparse: context imbalance in '_raw_read_unlock_bh' - unexpected unlock
   kernel/locking/spinlock.c:293:17: sparse: sparse: context imbalance in '_raw_write_lock' - wrong count at exit
>> arch/x86/include/asm/preempt.h:79:9: sparse: sparse: context imbalance in '_raw_write_lock_irqsave' - wrong count at exit
>> arch/x86/include/asm/preempt.h:79:9: sparse: sparse: context imbalance in '_raw_write_lock_irq' - wrong count at exit
   kernel/locking/spinlock.c:317:17: sparse: sparse: context imbalance in '_raw_write_lock_bh' - wrong count at exit
   kernel/locking/spinlock.c:325:17: sparse: sparse: context imbalance in '_raw_write_unlock' - unexpected unlock
   kernel/locking/spinlock.c:333:17: sparse: sparse: context imbalance in '_raw_write_unlock_irqrestore' - unexpected unlock
   kernel/locking/spinlock.c:341:17: sparse: sparse: context imbalance in '_raw_write_unlock_irq' - unexpected unlock
   kernel/locking/spinlock.c:349:17: sparse: sparse: context imbalance in '_raw_write_unlock_bh' - unexpected unlock
   kernel/locking/spinlock.c:358:17: sparse: sparse: context imbalance in '_raw_spin_lock_nested' - wrong count at exit
>> arch/x86/include/asm/preempt.h:79:9: sparse: sparse: context imbalance in '_raw_spin_lock_irqsave_nested' - wrong count at exit
   kernel/locking/spinlock.c:380:17: sparse: sparse: context imbalance in '_raw_spin_lock_nest_lock' - wrong count at exit
--
   kernel/trace/ring_buffer.c:699:32: sparse: sparse: incorrect type in return expression (different base types) @@     expected restricted __poll_t @@     got int @@
   kernel/trace/ring_buffer.c:699:32: sparse:     expected restricted __poll_t
   kernel/trace/ring_buffer.c:699:32: sparse:     got int
   kernel/trace/ring_buffer.c: note: in included file (through include/linux/irqflags.h, arch/x86/include/asm/special_insns.h, arch/x86/include/asm/processor.h, ...):
>> arch/x86/include/asm/irqflags.h:162:28: sparse: sparse: context imbalance in 'ring_buffer_peek' - different lock contexts for basic block
>> arch/x86/include/asm/irqflags.h:162:28: sparse: sparse: context imbalance in 'ring_buffer_consume' - different lock contexts for basic block
>> arch/x86/include/asm/irqflags.h:162:28: sparse: sparse: context imbalance in 'ring_buffer_empty' - different lock contexts for basic block
>> arch/x86/include/asm/irqflags.h:162:28: sparse: sparse: context imbalance in 'ring_buffer_empty_cpu' - different lock contexts for basic block

vim +/_raw_spin_lock_irqsave +79 arch/x86/include/asm/preempt.h

c2daa3bed53a811 Peter Zijlstra    2013-08-14  72  
c2daa3bed53a811 Peter Zijlstra    2013-08-14  73  /*
c2daa3bed53a811 Peter Zijlstra    2013-08-14  74   * The various preempt_count add/sub methods
c2daa3bed53a811 Peter Zijlstra    2013-08-14  75   */
c2daa3bed53a811 Peter Zijlstra    2013-08-14  76  
c2daa3bed53a811 Peter Zijlstra    2013-08-14  77  static __always_inline void __preempt_count_add(int val)
c2daa3bed53a811 Peter Zijlstra    2013-08-14  78  {
b3ca1c10d7b32fd Christoph Lameter 2014-04-07 @79  	raw_cpu_add_4(__preempt_count, val);
c2daa3bed53a811 Peter Zijlstra    2013-08-14  80  }
c2daa3bed53a811 Peter Zijlstra    2013-08-14  81  

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