On 03/12/2016 01:39 AM, Pooja Dhannawat wrote:
> Signed-off-by: Pooja Dhannawat <dhannawatpoo...@gmail.com>
> ---
> net/net.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/net/net.c b/net/net.c
> index b0c832e..5399758 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -709,16 +709,18 @@ ssize_t qemu_send_packet_raw(NetClientState *nc, const
> uint8_t *buf, int size)
> static ssize_t nc_sendv_compat(NetClientState *nc, const struct iovec *iov,
> int iovcnt, unsigned flags)
> {
> - uint8_t buf[NET_BUFSIZE];
> + uint8_t *buf;
> uint8_t *buffer;
> size_t offset;
>
> + buf = g_new(uint8_t, 1);
If you're only going to malloc() one byte, it's more efficient to just
stack-allocate it:
uint8_t buf[1];
Did you mean to do:
buf = g_new(uint8_t, NET_BUFSIZE)
instead?
> +
> if (iovcnt == 1) {
> buffer = iov[0].iov_base;
> offset = iov[0].iov_len;
> } else {
> buffer = buf;
> - offset = iov_to_buf(iov, iovcnt, 0, buf, sizeof(buf));
> + offset = iov_to_buf(iov, iovcnt, 0, (uint8_t *)buf, sizeof(uint8_t));
This is wrong. The old code used NET_BUFSIZE bytes for iov_to_buf(),
the new code uses only one byte. By the way, sizeof(char) and
sizeof(uint8_t) are pointless in code, as they are strictly equivalent to 1.
I agree that the idea behind the patch is useful (NET_BUFSIZE is 68k,
which is too large for our goal of at most 4k stack allocation if we
never want to overflow a stack guard page), but you'll need a correct
working version of the patch.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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