(2012/09/25 22:47), sjur.brandel...@stericsson.com wrote:
> From: Sjur Brændeland <sjur.brandel...@stericsson.com>
>
> This merge reduces code size by unifying the approach for
> sending scatter-lists and regular buffers. Any type of
> write operation (splice, write, put_chars) will now allocate
> a port_buffer and send_buf() and free_buf() can always be used.
Thanks!
This looks much nicer and simpler. I just have some comments below.
> Signed-off-by: Sjur Brændeland <sjur.brandel...@stericsson.com>
> cc: Rusty Russell <ru...@rustcorp.com.au>
> cc: Michael S. Tsirkin <m...@redhat.com>
> cc: Amit Shah <amit.s...@redhat.com>
> cc: Linus Walleij <linus.wall...@linaro.org>
> cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
> ---
> drivers/char/virtio_console.c | 141
> ++++++++++++++++++-----------------------
> 1 files changed, 62 insertions(+), 79 deletions(-)
>
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 8ab9c3d..f4f7b04 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -111,6 +111,11 @@ struct port_buffer {
> size_t len;
> /* offset in the buf from which to consume data */
> size_t offset;
> +
> + /* If sgpages == 0 then buf is used, else sg is used */
> + unsigned int sgpages;
> +
> + struct scatterlist sg[1];
> };
>
> /*
> @@ -338,23 +343,46 @@ static inline bool use_multiport(struct ports_device
> *portdev)
>
> static void free_buf(struct port_buffer *buf)
> {
> + int i;
> +
> kfree(buf->buf);
this should be done only when !buf->sgpages, or (see below)
> +
> + if (buf->sgpages)
> + for (i = 0; i < buf->sgpages; i++) {
> + struct page *page = sg_page(&buf->sg[i]);
> + if (!page)
> + break;
> + put_page(page);
> + }
> +
> kfree(buf);
> }
>
> -static struct port_buffer *alloc_buf(size_t buf_size)
> +static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,
> + int nrbufs)
> {
> struct port_buffer *buf;
> + size_t alloc_size;
>
> - buf = kmalloc(sizeof(*buf), GFP_KERNEL);
> + /* Allocate buffer and the scatter list */
> + alloc_size = sizeof(*buf) + sizeof(struct scatterlist) * nrbufs;
This allocates one redundant sg entry when nrbuf > 0,
but I think it is OK. (just a comment)
> + buf = kmalloc(alloc_size, GFP_ATOMIC);
This should be kzalloc(), or buf->buf and others are not initialized,
which will cause unexpected kfree bug at kfree(buf->buf) in free_buf.
> if (!buf)
> goto fail;
> - buf->buf = kzalloc(buf_size, GFP_KERNEL);
> +
> + buf->sgpages = nrbufs;
> + if (nrbufs > 0)
> + return buf;
> +
> + buf->buf = kmalloc(buf_size, GFP_ATOMIC);
You can also use kzalloc here as previous code does.
But if the reason why using kzalloc comes from the security,
I think kmalloc is enough here, since the host can access
all the guest pages anyway.
> if (!buf->buf)
> goto free_buf;
> buf->len = 0;
> buf->offset = 0;
> buf->size = buf_size;
> +
> + /* Prepare scatter buffer for sending */
> + sg_init_one(buf->sg, buf->buf, buf_size);
> return buf;
>
> free_buf:
Thank you,
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
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