> -----Original Message-----
> From: John Levon <[email protected]>
> Sent: 17 November 2025 15:57
> To: [email protected]
> Cc: John Levon <[email protected]>; Thanos Makatos
> <[email protected]>; Cédric Le Goater <[email protected]>; Peter
> Maydell <[email protected]>
> Subject: [PATCH v2 4/5] vfio-user: simplify vfio_user_recv_one()
>
> This function was unnecessarily difficult to understand due to the
> separate handling of request and reply messages. Use common code for
> both where we can.
>
> Signed-off-by: John Levon <[email protected]>
> ---
> hw/vfio-user/proxy.c | 68 +++++++++++++++++++-------------------------
> 1 file changed, 30 insertions(+), 38 deletions(-)
>
> diff --git a/hw/vfio-user/proxy.c b/hw/vfio-user/proxy.c
> index 87e50501af..aa5b971fb6 100644
> --- a/hw/vfio-user/proxy.c
> +++ b/hw/vfio-user/proxy.c
> @@ -281,15 +281,14 @@ static int vfio_user_recv_hdr(VFIOUserProxy *proxy,
> Error **errp,
> */
> static int vfio_user_recv_one(VFIOUserProxy *proxy, Error **errp)
> {
> - VFIOUserMsg *msg = NULL;
> g_autofree int *fdp = NULL;
> - VFIOUserFDs *reqfds;
> - VFIOUserHdr hdr;
> + VFIOUserMsg *msg = NULL;
> bool isreply = false;
> - int i, ret;
> - size_t msgleft, numfds = 0;
> + size_t msgleft = 0;
> + size_t numfds = 0;
> char *data = NULL;
> - char *buf = NULL;
> + VFIOUserHdr hdr;
> + int i, ret;
>
> /*
> * Complete any partial reads
> @@ -317,8 +316,8 @@ static int vfio_user_recv_one(VFIOUserProxy *proxy,
> Error **errp)
> }
>
> /*
> - * For replies, find the matching pending request.
> - * For requests, reap incoming FDs.
> + * Find the matching request if this is a reply, or initialize a new
> + * server->client request.
> */
> if (isreply) {
> QTAILQ_FOREACH(msg, &proxy->pending, next) {
> @@ -332,51 +331,44 @@ static int vfio_user_recv_one(VFIOUserProxy
> *proxy, Error **errp)
> }
> QTAILQ_REMOVE(&proxy->pending, msg, next);
>
> - /*
> - * Process any received FDs
> - */
> - if (numfds != 0) {
> - if (msg->fds == NULL || msg->fds->recv_fds < numfds) {
> - error_setg(errp, "unexpected FDs");
> - goto err;
> - }
> - msg->fds->recv_fds = numfds;
> - memcpy(msg->fds->fds, fdp, numfds * sizeof(int));
> - }
> - } else {
> - if (numfds != 0) {
> - reqfds = vfio_user_getfds(numfds);
> - memcpy(reqfds->fds, fdp, numfds * sizeof(int));
> - } else {
> - reqfds = NULL;
> - }
> - }
> -
> - /*
> - * Put the whole message into a single buffer.
> - */
> - if (isreply) {
> if (hdr.size > msg->rsize) {
> error_setg(errp, "reply larger than recv buffer");
> goto err;
> }
> - *msg->hdr = hdr;
> - data = (char *)msg->hdr + sizeof(hdr);
> } else {
> + void *buf;
> +
> if (hdr.size > proxy->max_xfer_size + sizeof(VFIOUserDMARW)) {
> error_setg(errp, "vfio_user_recv request larger than max");
> goto err;
> }
> +
> buf = g_malloc0(hdr.size);
> - memcpy(buf, &hdr, sizeof(hdr));
> - data = buf + sizeof(hdr);
> - msg = vfio_user_getmsg(proxy, (VFIOUserHdr *)buf, reqfds);
> + msg = vfio_user_getmsg(proxy, buf, NULL);
> msg->type = VFIO_MSG_REQ;
> }
>
> + *msg->hdr = hdr;
> + data = (char *)msg->hdr + sizeof(hdr);
> +
> + if (numfds != 0) {
> + if (msg->type == VFIO_MSG_REQ) {
> + msg->fds = vfio_user_getfds(numfds);
> + } else {
> + if (msg->fds == NULL || msg->fds->recv_fds < numfds) {
> + error_setg(errp, "unexpected FDs");
nit, "unexpected FDs in response"?
> + goto err;
> + }
> + msg->fds->recv_fds = numfds;
> + }
> +
> + memcpy(msg->fds->fds, fdp, numfds * sizeof(int));
> + }
> +
> /*
> - * Read rest of message.
> + * Read rest of message into the data buffer.
> */
> +
> msgleft = hdr.size - sizeof(hdr);
> while (msgleft > 0) {
> ret = qio_channel_read(proxy->ioc, data, msgleft, errp);
> --
> 2.43.0
Reviewed-by: Thanos Makatos <[email protected]>
