SELinux: remove the unused ae.used (906d27d9) · Commits · 戴 / test

Currently SELinux code has an atomic which was intended to track how many times an avc entry was used and to evict entries when they haven't been used recently. Instead we never let this atomic get above 1 and evict when it is first checked for eviction since it hits zero. This is a total waste of time so I'm completely dropping ae.used. This change resulted in about a 3% faster avc_has_perm_noaudit when running oprofile against a tbench benchmark. Signed-off-by:

Eric Paris <eparis@redhat.com> Reviewed by: Paul Moore <paul.moore@hp.com> Acked-by:

Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by:

James Morris <jmorris@namei.org>

security/selinux/avc.c

+7 −21

Original line number	Diff line number	Diff line
		@@ -88,7 +88,6 @@ struct avc_entry {
		u32 tsid;
		u16 tclass;
		struct av_decision avd;
		atomic_t used; /* used recently */
		};

		struct avc_node {
		@@ -316,8 +315,6 @@ static inline int avc_reclaim_node(void)

		rcu_read_lock();
		list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
		if (atomic_dec_and_test(&node->ae.used)) {
		/* Recently Unused */
		avc_node_delete(node);
		avc_cache_stats_incr(reclaims);
		ecx++;
		@@ -327,7 +324,6 @@ static inline int avc_reclaim_node(void)
		goto out;
		}
		}
		}
		rcu_read_unlock();
		spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
		}
		@@ -345,7 +341,6 @@ static struct avc_node *avc_alloc_node(void)

		INIT_RCU_HEAD(&node->rhead);
		INIT_LIST_HEAD(&node->list);
		atomic_set(&node->ae.used, 1);
		avc_cache_stats_incr(allocations);

		if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
		@@ -378,15 +373,6 @@ static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
		}
		}

		if (ret == NULL) {
		/* cache miss */
		goto out;
		}

		/* cache hit */
		if (atomic_read(&ret->ae.used) != 1)
		atomic_set(&ret->ae.used, 1);
		out:
		return ret;
		}

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