Static buffers shared across all call sites are not safe when multiple
worker threads handle TCP connections concurrently.
In tcp.c, move tcp_iov[] from file scope into tcp_data_from_tap() where
it is exclusively used. At UIO_MAXIOV (1024) entries of struct iovec
(16 bytes each), this adds 16 KiB to the stack frame.
In tcp_vu.c, move iov_vu[], elem[], and frame[] from file scope into
tcp_vu_data_from_sock() and pass them to tcp_vu_sock_recv() as
parameters. Also make iov_msg[] in tcp_vu_sock_recv() a local variable
instead of static, as it is only used within a single call. Combined,
these add roughly 80 KiB across the nested stack frames, which is
acceptable for per-thread stacks.
Signed-off-by: Laurent Vivier
---
tcp.c | 3 +--
tcp_vu.c | 33 ++++++++++++++++++++-------------
2 files changed, 21 insertions(+), 15 deletions(-)
diff --git a/tcp.c b/tcp.c
index 1549e14adaf4..f4fe866ba7c3 100644
--- a/tcp.c
+++ b/tcp.c
@@ -435,8 +435,6 @@ static socklen_t tcp_info_size;
/* Kernel reports delivery rate in TCP_INFO (kernel commit eb8329e0a04d) */
#define delivery_rate_cap tcp_info_cap(delivery_rate)
-/* sendmsg() to socket */
-static struct iovec tcp_iov [UIO_MAXIOV];
/* Pools for pre-opened sockets (in init) */
int init_sock_pool4 [TCP_SOCK_POOL_SIZE];
@@ -1900,6 +1898,7 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
uint16_t max_ack_seq_wnd = conn->wnd_from_tap;
uint32_t max_ack_seq = conn->seq_ack_from_tap;
uint32_t seq_from_tap = conn->seq_from_tap;
+ struct iovec tcp_iov[UIO_MAXIOV];
struct msghdr mh = { .msg_iov = tcp_iov };
size_t len;
ssize_t n;
diff --git a/tcp_vu.c b/tcp_vu.c
index 4f76f599156f..9270ece43d17 100644
--- a/tcp_vu.c
+++ b/tcp_vu.c
@@ -35,9 +35,6 @@
#include "vu_common.h"
#include
-static struct iovec iov_vu[VIRTQUEUE_MAX_SIZE];
-static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
-
/**
* struct vu_frame - Descriptor for a TCP frame mapped to virtqueue elements
* @idx_element: Index of first element in elem[] for this frame
@@ -46,13 +43,13 @@ static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
* @num_iovec: Number of iovecs covering this frame's buffers
* @size: Total frame size including all headers
*/
-static struct vu_frame {
+struct vu_frame {
int idx_element;
int num_element;
int idx_iovec;
int num_iovec;
size_t size;
-} frame[VIRTQUEUE_MAX_SIZE];
+};
/**
* tcp_vu_hdrlen() - Sum size of all headers, from TCP to virtio-net
@@ -224,6 +221,9 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags,
* @v6: Set for IPv6 connections
* @already_sent: Number of bytes already sent
* @fillsize: Maximum bytes to fill in guest-side receiving window
+ * @iov_vu: IO vector array for virtqueue buffers
+ * @elem: Virtqueue element array
+ * @frame: Frame descriptor array
* @elem_used: number of element (output)
* @frame_cnt: Pointer to store the number of frames (output)
*
@@ -233,9 +233,12 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags,
static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
const struct tcp_tap_conn *conn, bool v6,
uint32_t already_sent, size_t fillsize,
+ struct iovec *iov_vu,
+ struct vu_virtq_element *elem,
+ struct vu_frame *frame,
int *elem_used, int *frame_cnt)
{
- static struct iovec iov_msg[VIRTQUEUE_MAX_SIZE + DISCARD_IOV_NUM];
+ struct iovec iov_msg[VIRTQUEUE_MAX_SIZE + DISCARD_IOV_NUM];
const struct vu_dev *vdev = c->vdev;
struct msghdr mh_sock = { 0 };
uint16_t mss = MSS_GET(conn);
@@ -252,16 +255,16 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
iov_used = 0;
elem_cnt = 0;
*frame_cnt = 0;
- while (fillsize > 0 && elem_cnt < ARRAY_SIZE(elem) &&
- iov_used < ARRAY_SIZE(iov_vu) &&
- *frame_cnt < ARRAY_SIZE(frame)) {
+ while (fillsize > 0 && elem_cnt < VIRTQUEUE_MAX_SIZE &&
+ iov_used < VIRTQUEUE_MAX_SIZE &&
+ *frame_cnt < VIRTQUEUE_MAX_SIZE) {
size_t frame_size, in_total;
int cnt;
cnt = vu_collect(vdev, vq, &elem[elem_cnt],
- ARRAY_SIZE(elem) - elem_cnt,
+ VIRTQUEUE_MAX_SIZE - elem_cnt,
&iov_vu[iov_used],
- ARRAY_SIZE(iov_vu) - iov_used, &in_total,
+ VIRTQUEUE_MAX_SIZE - iov_used, &in_total,
MIN(mss, fillsize) + hdrlen,
&frame_size);
if (cnt == 0)
@@ -327,7 +330,8 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq,
if ((size_t)ret <= f->size - hdrlen) {
unsigned cnt;
- cnt = iov_skip_bytes(&iov_vu[f->idx_iovec], f->num_iovec,
+ cnt = iov_skip_bytes(&iov_vu[f->idx_iovec],
+ f->num_iovec,
MAX(hdrlen + ret, VNET_HLEN + ETH_ZLEN),
NULL);
if (cnt < (unsigned)f->num_iovec)
@@ -433,6 +437,9 @@ static void tcp_vu_prepare(const struct ctx *c, struct tcp_tap_conn *conn,
int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn,
unsigned int qpair)
{
+ struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
+ struct iovec iov_vu[VIRTQUEUE_MAX_SIZE];
+ struct vu_frame frame[VIRTQUEUE_MAX_SIZE];
uint32_t wnd_scaled = conn->wnd_from_tap << conn->ws_from_tap;
int rx_queue = QPAIR_TOGUEST_QUEUE(qpair);
struct vu_dev *vdev = c->vdev;
@@ -477,7 +484,7 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn,
* data from the socket
*/
len = tcp_vu_sock_recv(c, vq, conn, v6, already_sent, fillsize,
- &elem_cnt, &frame_cnt);
+ iov_vu, elem, frame, &elem_cnt, &frame_cnt);
if (len < 0) {
if (len != -EAGAIN && len != -EWOULDBLOCK) {
tcp_rst(c, conn, qpair);
--
2.54.0