[PATCH] virtio_console: fix sparse warnings

From: Michael S. Tsirkin
Date: Mon Dec 01 2014 - 06:36:16 EST

CHECK drivers/char/virtio_console.c
drivers/char/virtio_console.c:687:36: warning: incorrect type in
argument 1 (different address spaces)
drivers/char/virtio_console.c:687:36: expected void [noderef]
drivers/char/virtio_console.c:687:36: got char *out_buf
drivers/char/virtio_console.c:790:35: warning: incorrect type in
argument 2 (different address spaces)
drivers/char/virtio_console.c:790:35: expected char *out_buf
drivers/char/virtio_console.c:790:35: got char [noderef]

fill_readbuf is reused with both kernel and userspace pointers,
depending on value of to_user flag.

Tag address parameter as __user, and cast to/from regular pointer type
when we know it's safe.

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
drivers/char/virtio_console.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 775c898..ccb5357 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -669,8 +669,8 @@ done:
* Give out the data that's requested from the buffer that we have
* queued up.
-static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
- bool to_user)
+static ssize_t fill_readbuf(struct port *port, char __user *out_buf,
+ size_t out_count, bool to_user)
struct port_buffer *buf;
unsigned long flags;
@@ -688,7 +688,8 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
if (ret)
return -EFAULT;
} else {
- memcpy(out_buf, buf->buf + buf->offset, out_count);
+ memcpy((__force char *)out_buf, buf->buf + buf->offset,
+ out_count);

buf->offset += out_count;
@@ -1162,7 +1163,7 @@ static int get_chars(u32 vtermno, char *buf, int count)
/* If we don't have an input queue yet, we can't get input. */

- return fill_readbuf(port, buf, count, false);
+ return fill_readbuf(port, (__force char __user *)buf, count, false);

static void resize_console(struct port *port)
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