linux-kernel - [PATCH v9 01/20] crypto: change transient busy return code to -EAGAIN

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Message-Id: <1508059209-25529-2-git-send-email-gilad@benyossef.com>
Date:   Sun, 15 Oct 2017 10:19:46 +0100
From:   Gilad Ben-Yossef <gilad@...yossef.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Jonathan Corbet <corbet@....net>,
        David Howells <dhowells@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Gary Hook <gary.hook@....com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Arnaud Ebalard <arno@...isbad.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        Steve French <sfrench@...ba.org>,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <james.l.morris@...cle.com>,
        "Serge E. Hallyn" <serge@...lyn.com>
Cc:     Ofir Drang <ofir.drang@....com>, linux-crypto@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        keyrings@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-fscrypt@...r.kernel.org,
        netdev@...r.kernel.org, linux-ima-devel@...ts.sourceforge.net,
        linux-ima-user@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org
Subject: [PATCH v9 01/20] crypto: change transient busy return code to -EAGAIN

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 -EAGAIN.

Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
---
 crypto/algapi.c | 6 ++++--
 crypto/cryptd.c | 4 +---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/crypto/algapi.c b/crypto/algapi.c
index aa699ff..916bee3 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -897,9 +897,11 @@ int crypto_enqueue_request(struct crypto_queue *queue,
 	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 = -EAGAIN;
 			goto out;
+		}
+		err = -EBUSY;
 		if (queue->backlog == &queue->list)
 			queue->backlog = &request->list;
 	}
diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index 0508c48..d1dbdce 100644
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -137,16 +137,14 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
 	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 == -EAGAIN)
 		goto out_put_cpu;
 
 	queue_work_on(cpu, kcrypto_wq, &cpu_queue->work);
-- 
2.7.4