Commit 3dc3afad authored Jul 01, 2016 by Tal Shorer Committed by Christoph Hellwig Jul 10, 2016

configfs: don't set buffer_needs_fill to zero if show() returns error



A confgifs attribute's show() callback is called once the first time
the user attempts to read from it. If it returns an error, that
error is returned to the user. However, the open file's
buffer_needs_fill is still set to zero and consecutive read() calls
will find an empty buffer that doesn't need filling and return 0 to
the user. This could give the user the wrong impression that the
attribute was read successfully.

Fix this by not setting buffer_needs_fill if show() returns an error,
making consecutive read() calls call show() again and either get an
error again or get data.

Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

parent ee40fb29

fs/configfs/file.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -80,11 +80,11 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf

		count = attr->show(item, buffer->page);

		buffer->needs_read_fill = 0;
		BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
		if (count >= 0)
		if (count >= 0) {
		buffer->needs_read_fill = 0;
		buffer->count = count;
		else
		} else
		ret = count;
		return ret;
		}