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Date: Thu, 28 Apr 2022 15:11:42 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Maxim Mikityanskiy <maximmi@...dia.com>
Cc: "David S. Miller" <davem@...emloft.net>,
Daniel Borkmann <daniel@...earbox.net>,
Paolo Abeni <pabeni@...hat.com>,
Boris Pismenny <borisp@...dia.com>,
Tariq Toukan <tariqt@...dia.com>,
"Saeed Mahameed" <saeedm@...dia.com>,
Gal Pressman <gal@...dia.com>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] tls: Add opt-in zerocopy mode of sendfile()
> diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
> index b12f81a2b44c..715401b20c8b 100644
> --- a/net/tls/tls_device.c
> +++ b/net/tls/tls_device.c
> @@ -411,10 +411,16 @@ static int tls_device_copy_data(void *addr, size_t bytes, struct iov_iter *i)
> return 0;
> }
>
> +union tls_iter_offset {
> + struct iov_iter *msg_iter;
> + int offset;
> +};
Is this sort of atrocity used elsewhere in the kernel?
If you can't refactor the code you can pack args into
a structure but I've not seen people cast mutually exclusive
arguments to a union type. Is this "inspired" by some higher
level language?
> static int tls_push_data(struct sock *sk,
> - struct iov_iter *msg_iter,
> + union tls_iter_offset iter_offset,
> size_t size, int flags,
> - unsigned char record_type)
> + unsigned char record_type,
> + struct page *zc_page)
> {
> struct tls_context *tls_ctx = tls_get_ctx(sk);
> struct tls_prot_info *prot = &tls_ctx->prot_info;
> @@ -480,15 +486,29 @@ static int tls_push_data(struct sock *sk,
> }
>
> record = ctx->open_record;
> - copy = min_t(size_t, size, (pfrag->size - pfrag->offset));
> - copy = min_t(size_t, copy, (max_open_record_len - record->len));
> -
> - if (copy) {
> - rc = tls_device_copy_data(page_address(pfrag->page) +
> - pfrag->offset, copy, msg_iter);
> - if (rc)
> - goto handle_error;
> - tls_append_frag(record, pfrag, copy);
> +
> + if (!zc_page) {
> + copy = min_t(size_t, size, pfrag->size - pfrag->offset);
> + copy = min_t(size_t, copy, max_open_record_len - record->len);
Nope, refactor this please. 95% sure you don't need 4 indentation
levels here. Space left in record can be calculated before the if,
then you can do
if (zc_page) {
..
} else if (copy) {
..
}
> + if (copy) {
> + rc = tls_device_copy_data(page_address(pfrag->page) +
> + pfrag->offset, copy,
> + iter_offset.msg_iter);
> + if (rc)
> + goto handle_error;
> + tls_append_frag(record, pfrag, copy);
> + }
> + } else {
> + copy = min_t(size_t, size, max_open_record_len - record->len);
> + if (copy) {
> + struct page_frag _pfrag;
And name your variables right :/
> + _pfrag.page = zc_page;
> + _pfrag.offset = iter_offset.offset;
> + _pfrag.size = copy;
> + tls_append_frag(record, &_pfrag, copy);
> + }
> }
> size -= copy;
> @@ -551,8 +571,8 @@ int tls_device_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
> goto out;
> }
>
> - rc = tls_push_data(sk, &msg->msg_iter, size,
> - msg->msg_flags, record_type);
> + rc = tls_push_data(sk, (union tls_iter_offset)&msg->msg_iter, size,
> + msg->msg_flags, record_type, NULL);
>
> out:
> release_sock(sk);
> @@ -564,11 +584,14 @@ int tls_device_sendpage(struct sock *sk, struct page *page,
> int offset, size_t size, int flags)
> {
> struct tls_context *tls_ctx = tls_get_ctx(sk);
> + struct tls_offload_context_tx *ctx;
> struct iov_iter msg_iter;
> char *kaddr;
> struct kvec iov;
> int rc;
>
> + ctx = tls_offload_ctx_tx(tls_ctx);
> +
> if (flags & MSG_SENDPAGE_NOTLAST)
> flags |= MSG_MORE;
>
> @@ -580,12 +603,18 @@ int tls_device_sendpage(struct sock *sk, struct page *page,
> goto out;
> }
>
> + if (ctx->zerocopy_sendfile) {
> + rc = tls_push_data(sk, (union tls_iter_offset)offset, size,
> + flags, TLS_RECORD_TYPE_DATA, page);
> + goto out;
> + }
> +
> kaddr = kmap(page);
> iov.iov_base = kaddr + offset;
> iov.iov_len = size;
> iov_iter_kvec(&msg_iter, WRITE, &iov, 1, size);
> - rc = tls_push_data(sk, &msg_iter, size,
> - flags, TLS_RECORD_TYPE_DATA);
> + rc = tls_push_data(sk, (union tls_iter_offset)&msg_iter, size,
> + flags, TLS_RECORD_TYPE_DATA, NULL);
> kunmap(page);
>
> out:
> @@ -659,7 +688,8 @@ static int tls_device_push_pending_record(struct sock *sk, int flags)
> struct iov_iter msg_iter;
>
> iov_iter_kvec(&msg_iter, WRITE, NULL, 0, 0);
> - return tls_push_data(sk, &msg_iter, 0, flags, TLS_RECORD_TYPE_DATA);
> + return tls_push_data(sk, (union tls_iter_offset)&msg_iter, 0, flags,
> + TLS_RECORD_TYPE_DATA, NULL);
> }
>
> void tls_device_write_space(struct sock *sk, struct tls_context *ctx)
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> index 7b2b0e7ffee4..8ef86e04f571 100644
> --- a/net/tls/tls_main.c
> +++ b/net/tls/tls_main.c
> @@ -513,6 +513,31 @@ static int do_tls_getsockopt_conf(struct sock *sk, char __user *optval,
> return rc;
> }
>
> +static int do_tls_getsockopt_tx_zc(struct sock *sk, char __user *optval,
> + int __user *optlen)
> +{
> + struct tls_context *tls_ctx = tls_get_ctx(sk);
> + struct tls_offload_context_tx *ctx;
> + int len, value;
> +
> + if (get_user(len, optlen))
> + return -EFAULT;
> +
> + if (len != sizeof(value))
the size check should match the one in setsockopt()
> + return -EINVAL;
> +
> + if (!tls_ctx || tls_ctx->tx_conf != TLS_HW)
> + return -EBUSY;
see setsockopt()
> + ctx = tls_offload_ctx_tx(tls_ctx);
> +
> + value = ctx->zerocopy_sendfile;
> + if (copy_to_user(optval, &value, sizeof(value)))
> + return -EFAULT;
> +
> + return 0;
> +}
> +static int do_tls_setsockopt_tx_zc(struct sock *sk, sockptr_t optval,
> + unsigned int optlen)
> +{
> + struct tls_context *tls_ctx = tls_get_ctx(sk);
Highly annoying but each file has its own scheme of naming variables,
tls_main uses ctx for tls_context.
> + struct tls_offload_context_tx *ctx;
> + int val;
unsigned
> + if (!tls_ctx || tls_ctx->tx_conf != TLS_HW)
How's tls_ctx ever gonna be NULL here?
We should allow setting the option for non-HW. It's an opt-in, the app
has opted in, the fact that the kernel will not make use of the liberty
to apply the optimization is not important, no?
> + return -EINVAL;
> +
> + if (sockptr_is_null(optval) || optlen < sizeof(val))
> + return -EINVAL;
> +
> + if (copy_from_sockptr(&val, optval, sizeof(val)))
> + return -EFAULT;
> +
> + ctx = tls_offload_ctx_tx(tls_ctx);
> + ctx->zerocopy_sendfile = val;
if (val > 1)
EINVAL.
> + return 0;
> +}
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