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-rw-r--r--drivers/net/tun.c62
1 files changed, 38 insertions, 24 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 5cdcf92eb310..db690a372260 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1035,6 +1035,29 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
return 0;
}
+static unsigned long iov_pages(const struct iovec *iv, int offset,
+ unsigned long nr_segs)
+{
+ unsigned long seg, base;
+ int pages = 0, len, size;
+
+ while (nr_segs && (offset >= iv->iov_len)) {
+ offset -= iv->iov_len;
+ ++iv;
+ --nr_segs;
+ }
+
+ for (seg = 0; seg < nr_segs; seg++) {
+ base = (unsigned long)iv[seg].iov_base + offset;
+ len = iv[seg].iov_len - offset;
+ size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
+ pages += size;
+ offset = 0;
+ }
+
+ return pages;
+}
+
/* Get packet from user space buffer */
static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
void *msg_control, const struct iovec *iv,
@@ -1082,32 +1105,18 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
return -EINVAL;
}
- if (msg_control)
- zerocopy = true;
-
- if (zerocopy) {
- /* Userspace may produce vectors with count greater than
- * MAX_SKB_FRAGS, so we need to linearize parts of the skb
- * to let the rest of data to be fit in the frags.
- */
- if (count > MAX_SKB_FRAGS) {
- copylen = iov_length(iv, count - MAX_SKB_FRAGS);
- if (copylen < offset)
- copylen = 0;
- else
- copylen -= offset;
- } else
- copylen = 0;
- /* There are 256 bytes to be copied in skb, so there is enough
- * room for skb expand head in case it is used.
+ if (msg_control) {
+ /* There are 256 bytes to be copied in skb, so there is
+ * enough room for skb expand head in case it is used.
* The rest of the buffer is mapped from userspace.
*/
- if (copylen < gso.hdr_len)
- copylen = gso.hdr_len;
- if (!copylen)
- copylen = GOODCOPY_LEN;
+ copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN;
linear = copylen;
- } else {
+ if (iov_pages(iv, offset + copylen, count) <= MAX_SKB_FRAGS)
+ zerocopy = true;
+ }
+
+ if (!zerocopy) {
copylen = len;
linear = gso.hdr_len;
}
@@ -1121,8 +1130,13 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
if (zerocopy)
err = zerocopy_sg_from_iovec(skb, iv, offset, count);
- else
+ else {
err = skb_copy_datagram_from_iovec(skb, 0, iv, offset, len);
+ if (!err && msg_control) {
+ struct ubuf_info *uarg = msg_control;
+ uarg->callback(uarg, false);
+ }
+ }
if (err) {
tun->dev->stats.rx_dropped++;