On Tue, Mar 15, 2016 at 11:55:13PM +0530, Pooja Dhannawat wrote:
> nc_sendv_compat has a huge stack usage of 69680 bytes approx.
> Moving large arrays to heap to reduce stack usage.
>
> Signed-off-by: Pooja Dhannawat <dhannawatpoo...@gmail.com>
> ---
> net/net.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/net/net.c b/net/net.c
> index b0c832e..f03c571 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -709,23 +709,29 @@ 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;
> + ssize_t ret;
> +
> + buf = g_new(uint8_t, NET_BUFSIZE);
The linear buffer is only needed when iovcnt > 1. I suggest the
following instead:
uint8_t *buf = NULL;
if (iovcnt == 1) {
buffer = iov[0].iov_base;
offset = iov[0].iov_len;
} else {
buf = g_new(uint8_t, NET_BUFSIZE);
buffer = buf;
offset = iov_to_buf(iov, iovcnt, 0, buf, NET_BUFSIZE);
}
This way the allocation is only made when we actually need to linearize
the buffer.
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