From: Gilad Ben-Yossef <gilad@benyossef.com>
Date: Wed, 18 Oct 2017 08:00:33 +0100
Subject: crypto: change transient busy return code to -ENOSPC
Patch-mainline: v4.15-rc1
Git-commit: 6b80ea389a0bceee6a0a801474b78ad0a8cd034d
References: bsc#1097585 bsc#1097586 bsc#1097587 bsc#1097588 bsc#1097583 bsc#1097584

The crypto API was using the -EBUSY return value to indicate
both a hard failure to submit a crypto operation into a
transformation provider when the latter was busy and the backlog
mechanism was not enabled as well as a notification that the
operation was queued into the backlog when the backlog mechanism
was enabled.

Having the same return code indicate two very different conditions
depending on a flag is both error prone and requires extra runtime
check like the following to discern between the cases:

	if (err == -EINPROGRESS ||
	    (err == -EBUSY && (ahash_request_flags(req) &
			       CRYPTO_TFM_REQ_MAY_BACKLOG)))

This patch changes the return code used to indicate a crypto op
failed due to the transformation provider being transiently busy
to -ENOSPC.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 crypto/algapi.c |    6 ++++--
 crypto/cryptd.c |    4 +---
 2 files changed, 5 insertions(+), 5 deletions(-)

--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -897,9 +897,11 @@ int crypto_enqueue_request(struct crypto
 	int err = -EINPROGRESS;
 
 	if (unlikely(queue->qlen >= queue->max_qlen)) {
-		err = -EBUSY;
-		if (!(request->flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
+		if (!(request->flags & CRYPTO_TFM_REQ_MAY_BACKLOG)) {
+			err = -ENOSPC;
 			goto out;
+		}
+		err = -EBUSY;
 		if (queue->backlog == &queue->list)
 			queue->backlog = &request->list;
 	}
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -137,16 +137,14 @@ static int cryptd_enqueue_request(struct
 	int cpu, err;
 	struct cryptd_cpu_queue *cpu_queue;
 	atomic_t *refcnt;
-	bool may_backlog;
 
 	cpu = get_cpu();
 	cpu_queue = this_cpu_ptr(queue->cpu_queue);
 	err = crypto_enqueue_request(&cpu_queue->queue, request);
 
 	refcnt = crypto_tfm_ctx(request->tfm);
-	may_backlog = request->flags & CRYPTO_TFM_REQ_MAY_BACKLOG;
 
-	if (err == -EBUSY && !may_backlog)
+	if (err == -ENOSPC)
 		goto out_put_cpu;
 
 	queue_work_on(cpu, kcrypto_wq, &cpu_queue->work);