[Qemu-devel] [PATCH v4] net: Allocating Large sized arrays to heap

[Pooja Dhannawat]

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 
---
 net/net.c | 13 +
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/net.c b/net/net.c
index b0c832e..663da13 100644
--- a/net/net.c
+++ b/net/net.c
@@ -709,23 +709,28 @@ 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 = NULL;
 uint8_t *buffer;
 size_t offset;
+ssize_t ret;
 
 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, sizeof(buf));
+offset = iov_to_buf(iov, iovcnt, 0, buf, NET_BUFSIZE);
 }
 
 if (flags & QEMU_NET_PACKET_FLAG_RAW && nc->info->receive_raw) {
-return nc->info->receive_raw(nc, buffer, offset);
+ret = nc->info->receive_raw(nc, buffer, offset);
 } else {
-return nc->info->receive(nc, buffer, offset);
+ret = nc->info->receive(nc, buffer, offset);
 }
+
+g_free(buf);
+return ret;
 }
 
 ssize_t qemu_deliver_packet_iov(NetClientState *sender,
-- 
2.5.0

Re: [Qemu-devel] [PATCH v4] net: Allocating Large sized arrays to heap

[Stefan Hajnoczi]

On Thu, Mar 17, 2016 at 09:17:40PM +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 
> ---
>  net/net.c | 13 +
>  1 file changed, 9 insertions(+), 4 deletions(-)

Reviewed-by: Stefan Hajnoczi 


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