+static void ipcomp_free_scratches(void)
+{
+ int i;
+ void **scratches;
+
+ if (--ipcomp_scratch_users)
+ return;
+
+ scratches = ipcomp_scratches;
+ if (!scratches)
+ return;
+
+ for_each_possible_cpu(i)
+ vfree(*per_cpu_ptr(scratches, i));
+
+ free_percpu(scratches);
+}
+
+static void **ipcomp_alloc_scratches(void)
+{
+ int i;
+ void **scratches;
+
+ if (ipcomp_scratch_users++)
+ return ipcomp_scratches;
+
+ scratches = alloc_percpu(void *);
+ if (!scratches)
+ return NULL;
+
+ ipcomp_scratches = scratches;
+
+ for_each_possible_cpu(i) {
+ void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
+ if (!scratch)
+ return NULL;
+ *per_cpu_ptr(scratches, i) = scratch;
+ }
+
+ return scratches;
+}
+
+static void ipcomp_free_tfms(struct crypto_comp **tfms)
+{
+ struct ipcomp_tfms *pos;
+ int cpu;
+
+ list_for_each_entry(pos, &ipcomp_tfms_list, list) {
+ if (pos->tfms == tfms)
+ break;
+ }
+
+ BUG_TRAP(pos);
+
+ if (--pos->users)
+ return;
+
+ list_del(&pos->list);
+ kfree(pos);
+
+ if (!tfms)
+ return;
+
+ for_each_possible_cpu(cpu) {
+ struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
+ crypto_free_comp(tfm);
+ }
+ free_percpu(tfms);
+}
+
+static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
+{
+ struct ipcomp_tfms *pos;
+ struct crypto_comp **tfms;
+ int cpu;
+
+ /* This can be any valid CPU ID so we don't need locking. */
+ cpu = raw_smp_processor_id();
+
+ list_for_each_entry(pos, &ipcomp_tfms_list, list) {
+ struct crypto_comp *tfm;
+
+ tfms = pos->tfms;
+ tfm = *per_cpu_ptr(tfms, cpu);
+
+ if (!strcmp(crypto_comp_name(tfm), alg_name)) {
+ pos->users++;
+ return tfms;
+ }
+ }
+
+ pos = kmalloc(sizeof(*pos), GFP_KERNEL);
+ if (!pos)
+ return NULL;
+
+ pos->users = 1;
+ INIT_LIST_HEAD(&pos->list);
+ list_add(&pos->list, &ipcomp_tfms_list);
+
+ pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
+ if (!tfms)
+ goto error;
+
+ for_each_possible_cpu(cpu) {
+ struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
+ CRYPTO_ALG_ASYNC);
+ if (!tfm)
+ goto error;
+ *per_cpu_ptr(tfms, cpu) = tfm;
+ }
+
+ return tfms;
+
+error:
+ ipcomp_free_tfms(tfms);
+ return NULL;
+}
+