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Date: Thu, 14 Jan 2016 18:25:27 +0100 From: Florian Westphal <fw@...len.de> To: Sasha Levin <sasha.levin@...cle.com> Cc: pablo@...filter.org, kaber@...sh.net, kadlec@...ckhole.kfki.hu, davem@...emloft.net, netfilter-devel@...r.kernel.org, coreteam@...filter.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2] netfilter: nf_conntrack: use safer way to lock all buckets Sasha Levin <sasha.levin@...cle.com> wrote: > When we need to lock all buckets in the connection hashtable we'd attempt to > lock 1024 spinlocks, which is way more preemption levels than supported by > the kernel. Furthermore, this behavior was hidden by checking if lockdep is > enabled, and if it was - use only 8 buckets(!). > > Fix this by using a global lock and synchronize all buckets on it when we > need to lock them all. This is pretty heavyweight, but is only done when we > need to resize the hashtable, and that doesn't happen often enough (or at all). > > diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c > index 3cb3cb8..4ccf5ad 100644 > --- a/net/netfilter/nf_conntrack_core.c > +++ b/net/netfilter/nf_conntrack_core.c > @@ -66,6 +66,21 @@ EXPORT_SYMBOL_GPL(nf_conntrack_locks); > __cacheline_aligned_in_smp DEFINE_SPINLOCK(nf_conntrack_expect_lock); > EXPORT_SYMBOL_GPL(nf_conntrack_expect_lock); > > +spinlock_t nf_conntrack_locks_all_lock; > +bool nf_conntrack_locks_all; warning: symbol 'nf_conntrack_locks_all_lock' was not declared. Should it be static? warning: symbol 'nf_conntrack_locks_all' was not declared. Should it be static? > +void nf_conntrack_lock(spinlock_t *lock) __acquires(lock) It avoids 'context imbalance in 'nf_conntrack_lock' - wrong count at exit' sparse error. Other than that this looks good, thanks.
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