splice: comparing unsigned int < 0

"ret" needs to be signed or the error handling for splice_to_pipe() won't
work correctly.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Tom Zanussi <zanussi@comcast.net>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/relay.c

@@ -1215,14 +1215,14 @@ static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
 /*
  *	subbuf_splice_actor - splice up to one subbuf's worth of data
  */
-static int subbuf_splice_actor(struct file *in,
+static ssize_t subbuf_splice_actor(struct file *in,
 			       loff_t *ppos,
 			       struct pipe_inode_info *pipe,
 			       size_t len,
 			       unsigned int flags,
 			       int *nonpad_ret)
 {
-	unsigned int pidx, poff, total_len, subbuf_pages, nr_pages, ret;
+	unsigned int pidx, poff, total_len, subbuf_pages, nr_pages;
 	struct rchan_buf *rbuf = in->private_data;
 	unsigned int subbuf_size = rbuf->chan->subbuf_size;
 	uint64_t pos = (uint64_t) *ppos;
@@ -1241,6 +1241,7 @@ static int subbuf_splice_actor(struct file *in,
 		.ops = &relay_pipe_buf_ops,
 		.spd_release = relay_page_release,
 	};
+	ssize_t ret;
 
 	if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
 		return 0;