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Message-Id: <1418165438-2205-22-git-send-email-viro@ZenIV.linux.org.uk>
Date: Tue, 9 Dec 2014 22:50:35 +0000
From: Al Viro <viro@...IV.linux.org.uk>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 22/25] switch memcpy_to_msg() and skb_copy{,_and_csum}_datagram_msg() to primitives
From: Al Viro <viro@...iv.linux.org.uk>
... 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 <viro@...iv.linux.org.uk>
---
drivers/target/iscsi/iscsi_target_util.c | 12 +++----
include/linux/skbuff.h | 16 +++-------
net/core/datagram.c | 54 +++++++++++---------------------
3 files changed, 28 insertions(+), 54 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index ce87ce9..7c6a95b 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -1326,21 +1326,19 @@ static int iscsit_do_rx_data(
struct iscsi_conn *conn,
struct iscsi_data_count *count)
{
- int data = count->data_length, rx_loop = 0, total_rx = 0, iov_len;
- struct kvec *iov_p;
+ int data = count->data_length, rx_loop = 0, total_rx = 0;
struct msghdr msg;
if (!conn || !conn->sock || !conn->conn_ops)
return -1;
memset(&msg, 0, sizeof(struct msghdr));
-
- iov_p = count->iov;
- iov_len = count->iov_count;
+ iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC,
+ count->iov, count->iov_count, data);
while (total_rx < data) {
- rx_loop = kernel_recvmsg(conn->sock, &msg, iov_p, iov_len,
- (data - total_rx), MSG_WAITALL);
+ rx_loop = sock_recvmsg(conn->sock, &msg,
+ (data - total_rx), MSG_WAITALL);
if (rx_loop <= 0) {
pr_debug("rx_loop: %d total_rx: %d\n",
rx_loop, total_rx);
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 52cf1bd..4902f2d 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2651,17 +2651,10 @@ int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
struct msghdr *msg, int size)
{
- /* XXX: stripping const */
- return skb_copy_datagram_iovec(from, offset, (struct iovec *)msg->msg_iter.iov, size);
-}
-int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb, int hlen,
- struct iovec *iov);
-static inline int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
- struct msghdr *msg)
-{
- /* XXX: stripping const */
- return skb_copy_and_csum_datagram_iovec(skb, hlen, (struct iovec *)msg->msg_iter.iov);
+ return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
}
+int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
+ struct msghdr *msg);
int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
struct iov_iter *from, int len);
int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
@@ -2697,8 +2690,7 @@ static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
{
- /* XXX: stripping const */
- return memcpy_toiovec((struct iovec *)msg->msg_iter.iov, data, len);
+ return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
}
struct skb_checksum_ops {
diff --git a/net/core/datagram.c b/net/core/datagram.c
index b6e303b..41075ed 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
--
2.1.3
--
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