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tcp_vu: head_cnt need not be global

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head_cnt is a global variable which tracks how many entries in head[] are
currently used.  The fact that it's global obscures the fact that the
lifetime over which it has a meaningful value is quite short: a single
call to of tcp_vu_data_from_sock().

Make it a local to tcp_vu_data_from_sock() to make that lifetime clearer.
We keep the head[] array global for now - although technically it has the
same valid lifetime - because it's large enough we might not want to put
it on the stack.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2025-02-18 13:50:13 +11:00 committed by Stefano Brivio
parent 6b4065153c
commit 5a07eb3ccc
1 changed files with 11 additions and 10 deletions
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21
tcp_vu.c
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@ -38,7 +38,6 @@
static struct iovec iov_vu[VIRTQUEUE_MAX_SIZE + 1];
static struct vu_virtq_element elem[VIRTQUEUE_MAX_SIZE];
static int head[VIRTQUEUE_MAX_SIZE + 1];
static int head_cnt;
/**
* tcp_vu_hdrlen() - return the size of the header in level 2 frame (TCP)
@ -183,7 +182,7 @@ 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,
const struct tcp_tap_conn *conn, bool v6,
uint32_t already_sent, size_t fillsize,
int *iov_cnt)
int *iov_cnt, int *head_cnt)
{
struct vu_dev *vdev = c->vdev;
struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
@ -202,7 +201,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c,
vu_init_elem(elem, &iov_vu[1], VIRTQUEUE_MAX_SIZE);
elem_cnt = 0;
head_cnt = 0;
*head_cnt = 0;
while (fillsize > 0 && elem_cnt < VIRTQUEUE_MAX_SIZE) {
struct iovec *iov;
size_t frame_size, dlen;
@ -221,7 +220,7 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c,
ASSERT(iov->iov_len >= hdrlen);
iov->iov_base = (char *)iov->iov_base + hdrlen;
iov->iov_len -= hdrlen;
head[head_cnt++] = elem_cnt;
head[(*head_cnt)++] = elem_cnt;
fillsize -= dlen;
elem_cnt += cnt;
@ -261,17 +260,18 @@ static ssize_t tcp_vu_sock_recv(const struct ctx *c,
len -= iov->iov_len;
}
/* adjust head count */
while (head_cnt > 0 && head[head_cnt - 1] >= i)
head_cnt--;
while (*head_cnt > 0 && head[*head_cnt - 1] >= i)
(*head_cnt)--;
/* mark end of array */
head[head_cnt] = i;
head[*head_cnt] = i;
*iov_cnt = i;
/* release unused buffers */
vu_queue_rewind(vq, elem_cnt - i);
/* restore space for headers in iov */
for (i = 0; i < head_cnt; i++) {
for (i = 0; i < *head_cnt; i++) {
struct iovec *iov = &elem[head[i]].in_sg[0];
iov->iov_base = (char *)iov->iov_base - hdrlen;
@ -357,11 +357,11 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
struct vu_dev *vdev = c->vdev;
struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE];
ssize_t len, previous_dlen;
int i, iov_cnt, head_cnt;
size_t hdrlen, fillsize;
int v6 = CONN_V6(conn);
uint32_t already_sent;
const uint16_t *check;
int i, iov_cnt;
if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
debug("Got packet, but RX virtqueue not usable yet");
@ -396,7 +396,8 @@ int tcp_vu_data_from_sock(const struct ctx *c, struct tcp_tap_conn *conn)
/* collect the buffers from vhost-user and fill them with the
* data from the socket
*/
len = tcp_vu_sock_recv(c, conn, v6, already_sent, fillsize, &iov_cnt);
len = tcp_vu_sock_recv(c, conn, v6, already_sent, fillsize,
&iov_cnt, &head_cnt);
if (len < 0) {
if (len != -EAGAIN && len != -EWOULDBLOCK) {
tcp_rst(c, conn);