Re: [RFC PATCH 23/28] algif: Remove hash_sendpage*()

Re: [RFC PATCH 23/28] algif: Remove hash_sendpage*()

[David Howells]

Herbert Xu <herbert@gondor.apana.org.au> wrote:

> David Howells <dhowells@redhat.com> wrote:
> > Remove hash_sendpage*() and use hash_sendmsg() as the latter seems to just
> > use the source pages directly anyway.
> 
> ...
> 
> > -       if (!(flags & MSG_MORE)) {
> > -               if (ctx->more)
> > -                       err = crypto_ahash_finup(&ctx->req);
> > -               else
> > -                       err = crypto_ahash_digest(&ctx->req);
> 
> You've just removed the optimised path from user-space to
> finup/digest.  You need to add them back to sendmsg if you
> want to eliminate sendpage.

I must be missing something, I think.  What's particularly optimal about the
code in hash_sendpage() but not hash_sendmsg()?  Is it that the former uses
finup/digest, but the latter ony does update+final?

Also, looking at:

	if (!ctx->more) {
		if ((msg->msg_flags & MSG_MORE))
			hash_free_result(sk, ctx);

how is ctx->more meant to be interpreted?  I'm guessing it means that we're
continuing to the previous op.  But we do we need to free any old result if
MSG_MORE is set, but not if it isn't?

David

Re: [RFC PATCH 23/28] algif: Remove hash_sendpage*()

[David Howells]

Herbert Xu <herbert@gondor.apana.org.au> wrote:

> > I must be missing something, I think.  What's particularly optimal about the
> > code in hash_sendpage() but not hash_sendmsg()?  Is it that the former uses
> > finup/digest, but the latter ony does update+final?
> 
> A lot of hardware hashes can't perform partial updates, so they
> will always fall back to software unless you use finup/digest.

Okay.  Btw, how much of a hard limit is ALG_MAX_PAGES?  Multipage folios can
exceed the current limit (16 pages, 64K) in size.  Is it just to prevent too
much memory being pinned at once?

David

[RFC PATCH 23/28] algif: Remove hash_sendpage*()

[David Howells]

Remove hash_sendpage*() and use hash_sendmsg() as the latter seems to just
use the source pages directly anyway.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-crypto@vger.kernel.org
cc: netdev@vger.kernel.org
---
 crypto/algif_hash.c | 66 ---------------------------------------------
 1 file changed, 66 deletions(-)

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 1d017ec5c63c..52f5828a054a 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -129,58 +129,6 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
 	return err ?: copied;
 }
 
-static ssize_t hash_sendpage(struct socket *sock, struct page *page,
-			     int offset, size_t size, int flags)
-{
-	struct sock *sk = sock->sk;
-	struct alg_sock *ask = alg_sk(sk);
-	struct hash_ctx *ctx = ask->private;
-	int err;
-
-	if (flags & MSG_SENDPAGE_NOTLAST)
-		flags |= MSG_MORE;
-
-	lock_sock(sk);
-	sg_init_table(ctx->sgl.sg, 1);
-	sg_set_page(ctx->sgl.sg, page, size, offset);
-
-	if (!(flags & MSG_MORE)) {
-		err = hash_alloc_result(sk, ctx);
-		if (err)
-			goto unlock;
-	} else if (!ctx->more)
-		hash_free_result(sk, ctx);
-
-	ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, ctx->result, size);
-
-	if (!(flags & MSG_MORE)) {
-		if (ctx->more)
-			err = crypto_ahash_finup(&ctx->req);
-		else
-			err = crypto_ahash_digest(&ctx->req);
-	} else {
-		if (!ctx->more) {
-			err = crypto_ahash_init(&ctx->req);
-			err = crypto_wait_req(err, &ctx->wait);
-			if (err)
-				goto unlock;
-		}
-
-		err = crypto_ahash_update(&ctx->req);
-	}
-
-	err = crypto_wait_req(err, &ctx->wait);
-	if (err)
-		goto unlock;
-
-	ctx->more = flags & MSG_MORE;
-
-unlock:
-	release_sock(sk);
-
-	return err ?: size;
-}
-
 static int hash_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 			int flags)
 {
@@ -285,7 +233,6 @@ static struct proto_ops algif_hash_ops = {
 
 	.release	=	af_alg_release,
 	.sendmsg	=	hash_sendmsg,
-	.sendpage	=	hash_sendpage,
 	.recvmsg	=	hash_recvmsg,
 	.accept		=	hash_accept,
 };
@@ -337,18 +284,6 @@ static int hash_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
 	return hash_sendmsg(sock, msg, size);
 }
 
-static ssize_t hash_sendpage_nokey(struct socket *sock, struct page *page,
-				   int offset, size_t size, int flags)
-{
-	int err;
-
-	err = hash_check_key(sock);
-	if (err)
-		return err;
-
-	return hash_sendpage(sock, page, offset, size, flags);
-}
-
 static int hash_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
 			      size_t ignored, int flags)
 {
@@ -387,7 +322,6 @@ static struct proto_ops algif_hash_ops_nokey = {
 
 	.release	=	af_alg_release,
 	.sendmsg	=	hash_sendmsg_nokey,
-	.sendpage	=	hash_sendpage_nokey,
 	.recvmsg	=	hash_recvmsg_nokey,
 	.accept		=	hash_accept_nokey,
 };