netfilter: nft_set_pipapo: add helper to release pcpu scratch area

After next patch simple kfree() is not enough anymore, so add
a helper for it.

Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Author: Florian Westphal

net/netfilter/nft_set_pipapo.c

@@ -1110,6 +1110,24 @@ static void pipapo_map(struct nft_pipapo_match *m,
 		f->mt[map[i].to + j].e = e;
 }
 
+/**
+ * pipapo_free_scratch() - Free per-CPU map at original (not aligned) address
+ * @m:		Matching data
+ * @cpu:	CPU number
+ */
+static void pipapo_free_scratch(const struct nft_pipapo_match *m, unsigned int cpu)
+{
+	struct nft_pipapo_scratch *s;
+	void *mem;
+
+	s = *per_cpu_ptr(m->scratch, cpu);
+	if (!s)
+		return;
+
+	mem = s;
+	kfree(mem);
+}
+
 /**
  * pipapo_realloc_scratch() - Reallocate scratch maps for partial match results
  * @clone:	Copy of matching data with pending insertions and deletions
@@ -1142,7 +1160,7 @@ static int pipapo_realloc_scratch(struct nft_pipapo_match *clone,
 			return -ENOMEM;
 		}
 
-		kfree(*per_cpu_ptr(clone->scratch, i));
+		pipapo_free_scratch(clone, i);
 
 		*per_cpu_ptr(clone->scratch, i) = scratch;
 
@@ -1369,7 +1387,7 @@ static struct nft_pipapo_match *pipapo_clone(struct nft_pipapo_match *old)
 	}
 out_scratch_realloc:
 	for_each_possible_cpu(i)
-		kfree(*per_cpu_ptr(new->scratch, i));
+		pipapo_free_scratch(new, i);
 #ifdef NFT_PIPAPO_ALIGN
 	free_percpu(new->scratch_aligned);
 #endif
@@ -1653,7 +1671,7 @@ static void pipapo_free_match(struct nft_pipapo_match *m)
 	int i;
 
 	for_each_possible_cpu(i)
-		kfree(*per_cpu_ptr(m->scratch, i));
+		pipapo_free_scratch(m, i);
 
 #ifdef NFT_PIPAPO_ALIGN
 	free_percpu(m->scratch_aligned);
@@ -2253,7 +2271,7 @@ static void nft_pipapo_destroy(const struct nft_ctx *ctx,
 		free_percpu(m->scratch_aligned);
 #endif
 		for_each_possible_cpu(cpu)
-			kfree(*per_cpu_ptr(m->scratch, cpu));
+			pipapo_free_scratch(m, cpu);
 		free_percpu(m->scratch);
 		pipapo_free_fields(m);
 		kfree(m);
@@ -2270,7 +2288,7 @@ static void nft_pipapo_destroy(const struct nft_ctx *ctx,
 		free_percpu(priv->clone->scratch_aligned);
 #endif
 		for_each_possible_cpu(cpu)
-			kfree(*per_cpu_ptr(priv->clone->scratch, cpu));
+			pipapo_free_scratch(priv->clone, cpu);
 		free_percpu(priv->clone->scratch);
 
 		pipapo_free_fields(priv->clone);