padata: Make two separate cpumasks

The aim of this patch is to make two separate cpumasks
for padata parallel and serial workers respectively.
It allows user to make more thin and sophisticated configurations
of padata framework. For example user may bind parallel and serial workers to non-intersecting
CPU groups to gain better performance. Also each padata instance has notifiers chain for its
cpumasks now. If either parallel or serial or both masks were changed all
interested subsystems will get notification about that. It's especially useful
if padata user uses algorithm for callback CPU selection according to serial cpumask.

Signed-off-by: Dan Kruchinin <dkruchinin@acm.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 137 insertions, 54 deletions

diff --git a/crypto/pcrypt.c b/crypto/pcrypt.c
index 6036b6d..c9662e2 100644
--- a/crypto/pcrypt.c
+++ b/crypto/pcrypt.c
@@ -24,12 +24,38 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/notifier.h>
 #include <crypto/pcrypt.h>
 
-static struct padata_instance *pcrypt_enc_padata;
-static struct padata_instance *pcrypt_dec_padata;
-static struct workqueue_struct *encwq;
-static struct workqueue_struct *decwq;
+struct pcrypt_instance {
+	struct padata_instance *pinst;
+	struct workqueue_struct *wq;
+
+	/*
+	 * Cpumask for callback CPUs. It should be
+	 * equal to serial cpumask of corresponding padata instance,
+	 * so it is updated when padata notifies us about serial
+	 * cpumask change.
+	 *
+	 * cb_cpumask is protected by RCU. This fact prevents us from
+	 * using cpumask_var_t directly because the actual type of
+	 * cpumsak_var_t depends on kernel configuration(particularly on
+	 * CONFIG_CPUMASK_OFFSTACK macro). Depending on the configuration
+	 * cpumask_var_t may be either a pointer to the struct cpumask
+	 * or a variable allocated on the stack. Thus we can not safely use
+	 * cpumask_var_t with RCU operations such as rcu_assign_pointer or
+	 * rcu_dereference. So cpumask_var_t is wrapped with struct
+	 * pcrypt_cpumask which makes possible to use it with RCU.
+	 */
+	struct pcrypt_cpumask {
+		cpumask_var_t mask;
+	} *cb_cpumask;
+	struct notifier_block nblock;
+};
+
+static struct pcrypt_instance pencrypt;
+static struct pcrypt_instance pdecrypt;
+
 
 struct pcrypt_instance_ctx {
 	struct crypto_spawn spawn;
@@ -42,25 +68,29 @@ struct pcrypt_aead_ctx {
 };
 
 static int pcrypt_do_parallel(struct padata_priv *padata, unsigned int *cb_cpu,
-			      struct padata_instance *pinst)
+			      struct pcrypt_instance *pcrypt)
 {
 	unsigned int cpu_index, cpu, i;
+	struct pcrypt_cpumask *cpumask;
 
 	cpu = *cb_cpu;
 
-	if (cpumask_test_cpu(cpu, cpu_active_mask))
+	rcu_read_lock_bh();
+	cpumask = rcu_dereference(pcrypt->cb_cpumask);
+	if (cpumask_test_cpu(cpu, cpumask->mask))
 			goto out;
 
-	cpu_index = cpu % cpumask_weight(cpu_active_mask);
+	cpu_index = cpu % cpumask_weight(cpumask->mask);
 
-	cpu = cpumask_first(cpu_active_mask);
+	cpu = cpumask_first(cpumask->mask);
 	for (i = 0; i < cpu_index; i++)
-		cpu = cpumask_next(cpu, cpu_active_mask);
+		cpu = cpumask_next(cpu, cpumask->mask);
 
 	*cb_cpu = cpu;
 
 out:
-	return padata_do_parallel(pinst, padata, cpu);
+	rcu_read_unlock_bh();
+	return padata_do_parallel(pcrypt->pinst, padata, cpu);
 }
 
 static int pcrypt_aead_setkey(struct crypto_aead *parent,
@@ -142,7 +172,7 @@ static int pcrypt_aead_encrypt(struct aead_request *req)
 			       req->cryptlen, req->iv);
 	aead_request_set_assoc(creq, req->assoc, req->assoclen);
 
-	err = pcrypt_do_parallel(padata, &ctx->cb_cpu, pcrypt_enc_padata);
+	err = pcrypt_do_parallel(padata, &ctx->cb_cpu, &pencrypt);
 	if (!err)
 		return -EINPROGRESS;
 
@@ -184,7 +214,7 @@ static int pcrypt_aead_decrypt(struct aead_request *req)
 			       req->cryptlen, req->iv);
 	aead_request_set_assoc(creq, req->assoc, req->assoclen);
 
-	err = pcrypt_do_parallel(padata, &ctx->cb_cpu, pcrypt_dec_padata);
+	err = pcrypt_do_parallel(padata, &ctx->cb_cpu, &pdecrypt);
 	if (!err)
 		return -EINPROGRESS;
 
@@ -228,7 +258,7 @@ static int pcrypt_aead_givencrypt(struct aead_givcrypt_request *req)
 	aead_givcrypt_set_assoc(creq, areq->assoc, areq->assoclen);
 	aead_givcrypt_set_giv(creq, req->giv, req->seq);
 
-	err = pcrypt_do_parallel(padata, &ctx->cb_cpu, pcrypt_enc_padata);
+	err = pcrypt_do_parallel(padata, &ctx->cb_cpu, &pencrypt);
 	if (!err)
 		return -EINPROGRESS;
 
@@ -370,6 +400,88 @@ static void pcrypt_free(struct crypto_instance *inst)
 	kfree(inst);
 }
 
+static int pcrypt_cpumask_change_notify(struct notifier_block *self,
+					unsigned long val, void *data)
+{
+	struct pcrypt_instance *pcrypt;
+	struct pcrypt_cpumask *new_mask, *old_mask;
+
+	if (!(val & PADATA_CPU_SERIAL))
+		return 0;
+
+	pcrypt = container_of(self, struct pcrypt_instance, nblock);
+	new_mask = kmalloc(sizeof(*new_mask), GFP_KERNEL);
+	if (!new_mask)
+		return -ENOMEM;
+	if (!alloc_cpumask_var(&new_mask->mask, GFP_KERNEL)) {
+		kfree(new_mask);
+		return -ENOMEM;
+	}
+
+	old_mask = pcrypt->cb_cpumask;
+
+	padata_get_cpumask(pcrypt->pinst, PADATA_CPU_SERIAL, new_mask->mask);
+	rcu_assign_pointer(pcrypt->cb_cpumask, new_mask);
+	synchronize_rcu_bh();
+
+	free_cpumask_var(old_mask->mask);
+	kfree(old_mask);
+	return 0;
+}
+
+static int __pcrypt_init_instance(struct pcrypt_instance *pcrypt,
+				  const char *name)
+{
+	int ret = -ENOMEM;
+	struct pcrypt_cpumask *mask;
+
+	pcrypt->wq = create_workqueue(name);
+	if (!pcrypt->wq)
+		goto err;
+
+	pcrypt->pinst = padata_alloc(pcrypt->wq);
+	if (!pcrypt->pinst)
+		goto err_destroy_workqueue;
+
+	mask = kmalloc(sizeof(*mask), GFP_KERNEL);
+	if (!mask)
+		goto err_free_padata;
+	if (!alloc_cpumask_var(&mask->mask, GFP_KERNEL)) {
+		kfree(mask);
+		goto err_free_padata;
+	}
+
+	padata_get_cpumask(pcrypt->pinst, PADATA_CPU_SERIAL, mask->mask);
+	rcu_assign_pointer(pcrypt->cb_cpumask, mask);
+
+	pcrypt->nblock.notifier_call = pcrypt_cpumask_change_notify;
+	ret = padata_register_cpumask_notifier(pcrypt->pinst, &pcrypt->nblock);
+	if (ret)
+		goto err_free_cpumask;
+
+	return ret;
+err_free_cpumask:
+	free_cpumask_var(mask->mask);
+	kfree(mask);
+err_free_padata:
+	padata_free(pcrypt->pinst);
+err_destroy_workqueue:
+	destroy_workqueue(pcrypt->wq);
+err:
+	return ret;
+}
+
+static void __pcrypt_deinit_instance(struct pcrypt_instance *pcrypt)
+{
+	free_cpumask_var(pcrypt->cb_cpumask->mask);
+	kfree(pcrypt->cb_cpumask);
+
+	padata_stop(pcrypt->pinst);
+	padata_unregister_cpumask_notifier(pcrypt->pinst, &pcrypt->nblock);
+	destroy_workqueue(pcrypt->wq);
+	padata_free(pcrypt->pinst);
+}
+
 static struct crypto_template pcrypt_tmpl = {
 	.name = "pcrypt",
 	.alloc = pcrypt_alloc,
@@ -379,60 +491,31 @@ static struct crypto_template pcrypt_tmpl = {
 
 static int __init pcrypt_init(void)
 {
-	int err = -ENOMEM;
-	encwq = create_workqueue("pencrypt");
-	if (!encwq)
-		goto err;
-
-	decwq = create_workqueue("pdecrypt");
-	if (!decwq)
-		goto err_destroy_encwq;
-
-
-	pcrypt_enc_padata = padata_alloc(cpu_possible_mask, encwq);
-	if (!pcrypt_enc_padata)
-		goto err_destroy_decwq;
-
-	pcrypt_dec_padata = padata_alloc(cpu_possible_mask, decwq);
-	if (!pcrypt_dec_padata)
-		goto err_free_enc_padata;
+	int err;
 
-	err = padata_start(pcrypt_enc_padata);
+	err = __pcrypt_init_instance(&pencrypt, "pencrypt");
 	if (err)
-		goto err_free_dec_padata;
+		goto err;
 
-	err = padata_start(pcrypt_dec_padata);
+	err = __pcrypt_init_instance(&pdecrypt, "pdecrypt");
 	if (err)
-		goto err_free_dec_padata;
-
-	return crypto_register_template(&pcrypt_tmpl);
-
-err_free_dec_padata:
-	padata_free(pcrypt_dec_padata);
+		goto err_deinit_pencrypt;
 
-err_free_enc_padata:
-	padata_free(pcrypt_enc_padata);
+	padata_start(pencrypt.pinst);
+	padata_start(pdecrypt.pinst);
 
-err_destroy_decwq:
-	destroy_workqueue(decwq);
-
-err_destroy_encwq:
-	destroy_workqueue(encwq);
+	return crypto_register_template(&pcrypt_tmpl);
 
+err_deinit_pencrypt:
+	__pcrypt_deinit_instance(&pencrypt);
 err:
 	return err;
 }
 
 static void __exit pcrypt_exit(void)
 {
-	padata_stop(pcrypt_enc_padata);
-	padata_stop(pcrypt_dec_padata);
-
-	destroy_workqueue(encwq);
-	destroy_workqueue(decwq);
-
-	padata_free(pcrypt_enc_padata);
-	padata_free(pcrypt_dec_padata);
+	__pcrypt_deinit_instance(&pencrypt);
+	__pcrypt_deinit_instance(&pdecrypt);
 
 	crypto_unregister_template(&pcrypt_tmpl);
 }