From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83CA7C77B7D for ; Thu, 18 May 2023 09:57:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230299AbjERJ51 (ORCPT ); Thu, 18 May 2023 05:57:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38378 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230112AbjERJ50 (ORCPT ); Thu, 18 May 2023 05:57:26 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC7011A4 for ; Thu, 18 May 2023 02:56:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684403798; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dazR50SKXuYIFVWThl0nrv2fyFSamN4MkmMLPefBMF0=; b=X2gFKhXvosWcp8YL+9X5pR3n1H15RazWzM2IdeiWEReqij5QJEn/CHPRxXXz5jcz+DFLIs 1gtofvMVBUW7Uj8vmNlf1x8LcqOZNSwjaVOEOWpi7FYArIGNxV70iQ2kNp8t+1++xNgWRT eNwWy59ICcGTc0A+ABNiT0L1o5wsIW8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-352-sNI4QCQWN4qCpwaF8aO8pg-1; Thu, 18 May 2023 05:56:35 -0400 X-MC-Unique: sNI4QCQWN4qCpwaF8aO8pg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 07051800047; Thu, 18 May 2023 09:56:34 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.221]) by smtp.corp.redhat.com (Postfix) with ESMTP id 66B3640C2063; Thu, 18 May 2023 09:56:31 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20230515093345.396978-4-dhowells@redhat.com> References: <20230515093345.396978-4-dhowells@redhat.com> <20230515093345.396978-1-dhowells@redhat.com> To: Paolo Abeni Cc: dhowells@redhat.com, netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Willem de Bruijn , David Ahern , Matthew Wilcox , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH net-next v8 03/16] net: Add a function to splice pages into an skbuff for MSG_SPLICE_PAGES MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1347366.1684403790.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 18 May 2023 10:56:30 +0100 Message-ID: <1347367.1684403790@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org = Add a function to handle MSG_SPLICE_PAGES being passed internally to sendmsg(). Pages are spliced into the given socket buffer if possible and copied in if not (e.g. they're slab pages or have a zero refcount). Signed-off-by: David Howells cc: Eric Dumazet cc: "David S. Miller" cc: David Ahern cc: Jakub Kicinski cc: Paolo Abeni cc: Al Viro cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- Notes: ver #8) - Order local variables in reverse xmas tree order. - Remove duplicate coalescence check. - Warn if sendpage_ok() fails. = ver #7) - Export function. - Never copy data, return -EIO if sendpage_ok() returns false. include/linux/skbuff.h | 3 + net/core/skbuff.c | 88 +++++++++++++++++++++++++++++++++++++++++++= ++++++ 2 files changed, 91 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 4c0ad48e38ca..1c5f0ac6f8c3 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -5097,5 +5097,8 @@ static inline void skb_mark_for_recycle(struct sk_bu= ff *skb) #endif } = +ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter, + ssize_t maxsize, gfp_t gfp); + #endif /* __KERNEL__ */ #endif /* _LINUX_SKBUFF_H */ diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 7f53dcb26ad3..f4a5b51aed22 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -6892,3 +6892,91 @@ nodefer: __kfree_skb(skb); if (unlikely(kick) && !cmpxchg(&sd->defer_ipi_scheduled, 0, 1)) smp_call_function_single_async(cpu, &sd->defer_csd); } + +static void skb_splice_csum_page(struct sk_buff *skb, struct page *page, + size_t offset, size_t len) +{ + const char *kaddr; + __wsum csum; + + kaddr =3D kmap_local_page(page); + csum =3D csum_partial(kaddr + offset, len, 0); + kunmap_local(kaddr); + skb->csum =3D csum_block_add(skb->csum, csum, skb->len); +} + +/** + * skb_splice_from_iter - Splice (or copy) pages to skbuff + * @skb: The buffer to add pages to + * @iter: Iterator representing the pages to be added + * @maxsize: Maximum amount of pages to be added + * @gfp: Allocation flags + * + * This is a common helper function for supporting MSG_SPLICE_PAGES. It + * extracts pages from an iterator and adds them to the socket buffer if + * possible, copying them to fragments if not possible (such as if they'r= e slab + * pages). + * + * Returns the amount of data spliced/copied or -EMSGSIZE if there's + * insufficient space in the buffer to transfer anything. + */ +ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter, + ssize_t maxsize, gfp_t gfp) +{ + size_t frag_limit =3D READ_ONCE(sysctl_max_skb_frags); + struct page *pages[8], **ppages =3D pages; + ssize_t spliced =3D 0, ret =3D 0; + unsigned int i; + + while (iter->count > 0) { + ssize_t space, nr; + size_t off, len; + + ret =3D -EMSGSIZE; + space =3D frag_limit - skb_shinfo(skb)->nr_frags; + if (space < 0) + break; + + /* We might be able to coalesce without increasing nr_frags */ + nr =3D clamp_t(size_t, space, 1, ARRAY_SIZE(pages)); + + len =3D iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off); + if (len <=3D 0) { + ret =3D len ?: -EIO; + break; + } + + i =3D 0; + do { + struct page *page =3D pages[i++]; + size_t part =3D min_t(size_t, PAGE_SIZE - off, len); + + ret =3D -EIO; + if (WARN_ON_ONCE(!sendpage_ok(page))) + goto out; + + ret =3D skb_append_pagefrags(skb, page, off, part, + frag_limit); + if (ret < 0) { + iov_iter_revert(iter, len); + goto out; + } + + if (skb->ip_summed =3D=3D CHECKSUM_NONE) + skb_splice_csum_page(skb, page, off, part); + + off =3D 0; + spliced +=3D part; + maxsize -=3D part; + len -=3D part; + } while (len > 0); + + if (maxsize <=3D 0) + break; + } + +out: + skb_len_add(skb, spliced); + return spliced ?: ret; +} +EXPORT_SYMBOL(skb_splice_from_iter);