net/xfrm/xfrm_input.c:84:9: sparse: context imbalance in 'xfrm_rcv_cb' - unexpected unlock

net/xfrm/xfrm_input.c:84:9: sparse: context imbalance in 'xfrm_rcv_cb' - unexpected unlock

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   bf5f89463f5b3109a72ed13ca62b57e90213387d
commit: 960fdfdeb9e85a67bed136bc945c541ba61c2bdd xfrm: input: constify xfrm_input_afinfo
date:   3 months ago
reproduce:
        # apt-get install sparse
        git checkout 960fdfdeb9e85a67bed136bc945c541ba61c2bdd
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

   net/xfrm/xfrm_input.c:61:39: sparse: context imbalance in 'xfrm_input_get_afinfo' - different lock contexts for basic block
>> net/xfrm/xfrm_input.c:84:9: sparse: context imbalance in 'xfrm_rcv_cb' - unexpected unlock

vim +/xfrm_rcv_cb +84 net/xfrm/xfrm_input.c

2f32b51b Steffen Klassert 2014-03-14  55  	spin_unlock_bh(&xfrm_input_afinfo_lock);
2f32b51b Steffen Klassert 2014-03-14  56  	synchronize_rcu();
2f32b51b Steffen Klassert 2014-03-14  57  	return err;
2f32b51b Steffen Klassert 2014-03-14  58  }
2f32b51b Steffen Klassert 2014-03-14  59  EXPORT_SYMBOL(xfrm_input_unregister_afinfo);
2f32b51b Steffen Klassert 2014-03-14  60  
960fdfde Florian Westphal 2017-02-07 @61  static const struct xfrm_input_afinfo *xfrm_input_get_afinfo(unsigned int family)
2f32b51b Steffen Klassert 2014-03-14  62  {
960fdfde Florian Westphal 2017-02-07  63  	const struct xfrm_input_afinfo *afinfo;
2f32b51b Steffen Klassert 2014-03-14  64  
960fdfde Florian Westphal 2017-02-07  65  	if (WARN_ON_ONCE(family >= ARRAY_SIZE(xfrm_input_afinfo)))
2f32b51b Steffen Klassert 2014-03-14  66  		return NULL;
960fdfde Florian Westphal 2017-02-07  67  
2f32b51b Steffen Klassert 2014-03-14  68  	rcu_read_lock();
2f32b51b Steffen Klassert 2014-03-14  69  	afinfo = rcu_dereference(xfrm_input_afinfo[family]);
2f32b51b Steffen Klassert 2014-03-14  70  	if (unlikely(!afinfo))
2f32b51b Steffen Klassert 2014-03-14  71  		rcu_read_unlock();
2f32b51b Steffen Klassert 2014-03-14  72  	return afinfo;
2f32b51b Steffen Klassert 2014-03-14  73  }
2f32b51b Steffen Klassert 2014-03-14  74  
2f32b51b Steffen Klassert 2014-03-14  75  static int xfrm_rcv_cb(struct sk_buff *skb, unsigned int family, u8 protocol,
2f32b51b Steffen Klassert 2014-03-14  76  		       int err)
2f32b51b Steffen Klassert 2014-03-14  77  {
2f32b51b Steffen Klassert 2014-03-14  78  	int ret;
960fdfde Florian Westphal 2017-02-07  79  	const struct xfrm_input_afinfo *afinfo = xfrm_input_get_afinfo(family);
2f32b51b Steffen Klassert 2014-03-14  80  
2f32b51b Steffen Klassert 2014-03-14  81  	if (!afinfo)
2f32b51b Steffen Klassert 2014-03-14  82  		return -EAFNOSUPPORT;
2f32b51b Steffen Klassert 2014-03-14  83  
2f32b51b Steffen Klassert 2014-03-14 @84  	ret = afinfo->callback(skb, protocol, err);
960fdfde Florian Westphal 2017-02-07  85  	rcu_read_unlock();
2f32b51b Steffen Klassert 2014-03-14  86  
2f32b51b Steffen Klassert 2014-03-14  87  	return ret;

:::::: The code at line 84 was first introduced by commit
:::::: 2f32b51b609faea1e40bb8c5bd305f1351740936 xfrm: Introduce xfrm_input_afinfo to access the the callbacks properly

:::::: TO: Steffen Klassert <steffen.klassert@secunet.com>
:::::: CC: Steffen Klassert <steffen.klassert@secunet.com>

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