Re: [Qemu-devel] [PATCH v2 1/1] socket: Allocating Large sized arrays to heap

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Mar 14, 2016 at 10:07:53PM +0530, Pooja Dhannawat wrote:
> net_socket_send has a huge stack usage of 69712 bytes approx.
> Moving large arrays to heap to reduce stack usage.
> 
> Signed-off-by: Pooja Dhannawat <dhannawatpooja1@gmail.com>
> ---
>  net/socket.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/net/socket.c b/net/socket.c
> index e32e3cb..3fcd7a6 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -147,10 +147,10 @@ static void net_socket_send(void *opaque)
>      NetSocketState *s = opaque;
>      int size, err;
>      unsigned l;
> -    uint8_t buf1[NET_BUFSIZE];
> +    uint8_t *buf1 = g_new(uint8_t, NET_BUFSIZE);

You're allocating NET_BUFSIZE worth of uint8_t's

>      const uint8_t *buf;
>  
> -    size = qemu_recv(s->fd, buf1, sizeof(buf1), 0);
> +    size = qemu_recv(s->fd, (uint8_t *)buf1, sizeof(uint8_t), 0);

But only reading 1 byte which is clearly wrong. You likely wanted
NET_BUFSIZE here, not sizeof(uint8_t)

Regards,
Daniel
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