From e5a4b0bb803b39a36478451eae53a880d2663d5b Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 24 Nov 2014 18:17:55 -0500 Subject: switch memcpy_to_msg() and skb_copy{,_and_csum}_datagram_msg() to primitives ... making both non-draining. That means that tcp_recvmsg() becomes non-draining. And _that_ would break iscsit_do_rx_data() unless we a) make sure tcp_recvmsg() is uniformly non-draining (it is) b) make sure it copes with arbitrary (including shifted) iov_iter (it does, all it uses is iov_iter primitives) c) make iscsit_do_rx_data() initialize ->msg_iter only once. Fortunately, (c) is doable with minimal work and we are rid of one the two places where kernel send/recvmsg users would be unhappy with non-draining behaviour. Actually, that makes all but one of ->recvmsg() instances iov_iter-clean. The exception is skcipher_recvmsg() and it also isn't hard to convert to primitives (iov_iter_get_pages() is needed there). That'll wait a bit - there's some interplay with ->sendmsg() path for that one. Signed-off-by: Al Viro --- net/core/datagram.c | 54 +++++++++++++++++++---------------------------------- 1 file changed, 19 insertions(+), 35 deletions(-) (limited to 'net/core') diff --git a/net/core/datagram.c b/net/core/datagram.c index b6e303b0f01f..41075ed6bb52 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -615,27 +615,25 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from) EXPORT_SYMBOL(zerocopy_sg_from_iter); static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, - u8 __user *to, int len, + struct iov_iter *to, int len, __wsum *csump) { int start = skb_headlen(skb); int i, copy = start - offset; struct sk_buff *frag_iter; int pos = 0; + int n; /* Copy header. */ if (copy > 0) { - int err = 0; if (copy > len) copy = len; - *csump = csum_and_copy_to_user(skb->data + offset, to, copy, - *csump, &err); - if (err) + n = csum_and_copy_to_iter(skb->data + offset, copy, csump, to); + if (n != copy) goto fault; if ((len -= copy) == 0) return 0; offset += copy; - to += copy; pos = copy; } @@ -647,26 +645,22 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, end = start + skb_frag_size(frag); if ((copy = end - offset) > 0) { - __wsum csum2; - int err = 0; - u8 *vaddr; + __wsum csum2 = 0; struct page *page = skb_frag_page(frag); + u8 *vaddr = kmap(page); if (copy > len) copy = len; - vaddr = kmap(page); - csum2 = csum_and_copy_to_user(vaddr + - frag->page_offset + - offset - start, - to, copy, 0, &err); + n = csum_and_copy_to_iter(vaddr + frag->page_offset + + offset - start, copy, + &csum2, to); kunmap(page); - if (err) + if (n != copy) goto fault; *csump = csum_block_add(*csump, csum2, pos); if (!(len -= copy)) return 0; offset += copy; - to += copy; pos += copy; } start = end; @@ -691,7 +685,6 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, if ((len -= copy) == 0) return 0; offset += copy; - to += copy; pos += copy; } start = end; @@ -744,20 +737,19 @@ __sum16 __skb_checksum_complete(struct sk_buff *skb) EXPORT_SYMBOL(__skb_checksum_complete); /** - * skb_copy_and_csum_datagram_iovec - Copy and checksum skb to user iovec. + * skb_copy_and_csum_datagram_msg - Copy and checksum skb to user iovec. * @skb: skbuff * @hlen: hardware length - * @iov: io vector + * @msg: destination * * Caller _must_ check that skb will fit to this iovec. * * Returns: 0 - success. * -EINVAL - checksum failure. - * -EFAULT - fault during copy. Beware, in this case iovec - * can be modified! + * -EFAULT - fault during copy. */ -int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, - int hlen, struct iovec *iov) +int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, + int hlen, struct msghdr *msg) { __wsum csum; int chunk = skb->len - hlen; @@ -765,28 +757,20 @@ int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, if (!chunk) return 0; - /* Skip filled elements. - * Pretty silly, look at memcpy_toiovec, though 8) - */ - while (!iov->iov_len) - iov++; - - if (iov->iov_len < chunk) { + if (iov_iter_count(&msg->msg_iter) < chunk) { if (__skb_checksum_complete(skb)) goto csum_error; - if (skb_copy_datagram_iovec(skb, hlen, iov, chunk)) + if (skb_copy_datagram_msg(skb, hlen, msg, chunk)) goto fault; } else { csum = csum_partial(skb->data, hlen, skb->csum); - if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base, + if (skb_copy_and_csum_datagram(skb, hlen, &msg->msg_iter, chunk, &csum)) goto fault; if (csum_fold(csum)) goto csum_error; if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) netdev_rx_csum_fault(skb->dev); - iov->iov_len -= chunk; - iov->iov_base += chunk; } return 0; csum_error: @@ -794,7 +778,7 @@ csum_error: fault: return -EFAULT; } -EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec); +EXPORT_SYMBOL(skb_copy_and_csum_datagram_msg); /** * datagram_poll - generic datagram poll -- cgit v1.2.3-59-g8ed1b