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clarify and explain

This commit is contained in:
maxv 2020-03-22 15:14:03 +00:00
parent 86d91648b3
commit 7d1419fc37
1 changed files with 101 additions and 41 deletions
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142
sys/dev/usb/vhci.c
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@ -1,4 +1,4 @@
/* $NetBSD: vhci.c,v 1.8 2020/03/14 02:35:34 christos Exp $ */
/* $NetBSD: vhci.c,v 1.9 2020/03/22 15:14:03 maxv Exp $ */
/*
* Copyright (c) 2019 The NetBSD Foundation, Inc.
@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vhci.c,v 1.8 2020/03/14 02:35:34 christos Exp $");
__KERNEL_RCSID(0, "$NetBSD: vhci.c,v 1.9 2020/03/22 15:14:03 maxv Exp $");
#ifdef _KERNEL_OPT
#include "opt_usb.h"
@ -123,10 +123,62 @@ static const struct usbd_pipe_methods vhci_root_intr_methods = {
.upm_done = vhci_root_intr_done,
};
/*
* There are three structures to understand: vxfers, packets, and ports.
*
* Each xfer from the point of view of the USB stack is a vxfer from the point
* of view of vHCI.
*
* A vxfer has a linked list containing a maximum of two packets: a request
* packet and possibly a data packet. Packets basically contain data exchanged
* between the Host and the virtual USB device. A packet is linked to both a
* vxfer and a port.
*
* A port is an abstraction of an actual USB port. Each virtual USB device gets
* connected to a port. A port has two lists:
* - The Usb-To-Host list, containing packets to be fetched from the USB
* device and provided to the host.
* - The Host-To-Usb list, containing packets to be sent from the Host to the
* USB device.
* Request packets are always in the H->U direction. Data packets however can
* be in both the H->U and U->H directions.
*
* With read() and write() operations on /dev/vhci, userland respectively
* "fetches" and "sends" packets from or to the virtual USB device, which
* respectively means reading/inserting packets in the H->U and U->H lists on
* the port where the virtual USB device is connected.
*
* +------------------------------------------------+
* | USB Stack |
* +---------------------^--------------------------+
* |
* +---------------------V--------------------------+
* | +----------------+ +-------------+ |
* | | Request Packet | | Data Packet | Xfer |
* | +-------|--------+ +----|---^----+ |
* +---------|------------------|---|---------------+
* | | |
* | +--------------+ |
* | | |
* +---------|---|------------------|---------------+
* | +---V---V---+ +---------|-+ |
* | | H->U List | | U->H List | vHCI Port |
* | +-----|-----+ +-----^-----+ |
* +-----------|----------------|-------------------+
* | |
* +-----------|----------------|-------------------+
* | +-----V-----+ +-----|-----+ |
* | | read() | | write() | vHCI FD |
* | +-----------+ +-----------+ |
* +------------------------------------------------+
*/
struct vhci_xfer;
typedef struct vhci_packet {
TAILQ_ENTRY(vhci_packet) portlist;
TAILQ_ENTRY(vhci_packet) xferlist;
struct usbd_xfer *xfer; /* also vxfer */
struct vhci_xfer *vxfer;
bool utoh;
uint8_t *buf;
size_t size;
@ -153,10 +205,14 @@ typedef struct vhci_xfer {
/* General. */
struct usbd_xfer xfer;
/* vHCI-specific. */
size_t refcnt;
/* Port where the xfer occurs. */
vhci_port_t *port;
/* Packets in the xfer. */
size_t npkts;
vhci_packet_list_t pkts;
/* Used for G/C. */
TAILQ_ENTRY(vhci_xfer) freelist;
} vhci_xfer_t;
@ -200,61 +256,61 @@ static void
vhci_pkt_create(vhci_port_t *port, struct usbd_xfer *xfer, bool usb_to_host)
{
vhci_xfer_t *vxfer = (vhci_xfer_t *)xfer;
vhci_packet_list_t *reqlist, *pktlist;
vhci_packet_t *req, *pkt = NULL;
size_t refcnt = 0;
vhci_packet_list_t *reqlist, *datlist;
vhci_packet_t *req, *dat = NULL;
size_t npkts = 0;
/* Setup packet. */
/* Request packet. */
reqlist = &port->pkts_device_ctrl.host_to_usb;
req = kmem_zalloc(sizeof(*req), KM_SLEEP);
req->xfer = xfer;
req->vxfer = vxfer;
req->utoh = false;
req->buf = (uint8_t *)&xfer->ux_request;
req->size = sizeof(xfer->ux_request);
req->cursor = 0;
refcnt++;
npkts++;
/* Data packet. */
if (xfer->ux_length > 0) {
if (usb_to_host) {
pktlist = &port->pkts_device_ctrl.usb_to_host;
datlist = &port->pkts_device_ctrl.usb_to_host;
} else {
pktlist = &port->pkts_device_ctrl.host_to_usb;
datlist = &port->pkts_device_ctrl.host_to_usb;
}
pkt = kmem_zalloc(sizeof(*pkt), KM_SLEEP);
pkt->xfer = xfer;
pkt->utoh = usb_to_host;
pkt->buf = xfer->ux_buf;
pkt->size = xfer->ux_length;
pkt->cursor = 0;
refcnt++;
dat = kmem_zalloc(sizeof(*dat), KM_SLEEP);
dat->vxfer = vxfer;
dat->utoh = usb_to_host;
dat->buf = xfer->ux_buf;
dat->size = xfer->ux_length;
dat->cursor = 0;
npkts++;
}
/* Insert in the xfer. */
vxfer->refcnt = refcnt;
vxfer->port = port;
vxfer->npkts = npkts;
TAILQ_INIT(&vxfer->pkts);
TAILQ_INSERT_TAIL(&vxfer->pkts, req, xferlist);
if (pkt != NULL)
TAILQ_INSERT_TAIL(&vxfer->pkts, pkt, xferlist);
if (dat != NULL)
TAILQ_INSERT_TAIL(&vxfer->pkts, dat, xferlist);
/* Insert in the port. */
KASSERT(mutex_owned(&port->lock));
TAILQ_INSERT_TAIL(reqlist, req, portlist);
if (pkt != NULL)
TAILQ_INSERT_TAIL(pktlist, pkt, portlist);
if (dat != NULL)
TAILQ_INSERT_TAIL(datlist, dat, portlist);
}
static void
vhci_pkt_destroy(vhci_softc_t *sc, vhci_packet_t *pkt)
{
struct usbd_xfer *xfer = pkt->xfer;
vhci_xfer_t *vxfer = (vhci_xfer_t *)xfer;
vhci_xfer_t *vxfer = pkt->vxfer;
vhci_port_t *port = vxfer->port;
vhci_packet_list_t *pktlist;
KASSERT(mutex_owned(&port->lock));
/* Remove from the port. */
if (pkt->utoh) {
pktlist = &port->pkts_device_ctrl.usb_to_host;
} else {
@ -262,14 +318,15 @@ vhci_pkt_destroy(vhci_softc_t *sc, vhci_packet_t *pkt)
}
TAILQ_REMOVE(pktlist, pkt, portlist);
/* Remove from the xfer. */
TAILQ_REMOVE(&vxfer->pkts, pkt, xferlist);
kmem_free(pkt, sizeof(*pkt));
KASSERT(vxfer->refcnt > 0);
vxfer->refcnt--;
if (vxfer->refcnt > 0)
/* Unref. */
KASSERT(vxfer->npkts > 0);
vxfer->npkts--;
if (vxfer->npkts > 0)
return;
KASSERT(TAILQ_FIRST(&vxfer->pkts) == NULL);
}
@ -345,7 +402,7 @@ vhci_freex(struct usbd_bus *bus, struct usbd_xfer *xfer)
{
vhci_xfer_t *vxfer = (vhci_xfer_t *)xfer;
KASSERT(vxfer->refcnt == 0);
KASSERT(vxfer->npkts == 0);
KASSERT(TAILQ_FIRST(&vxfer->pkts) == NULL);
#ifdef DIAGNOSTIC
@ -562,7 +619,7 @@ vhci_device_ctrl_abort(struct usbd_xfer *xfer)
return;
mutex_enter(&port->lock);
while (vxfer->refcnt > 0) {
while (vxfer->npkts > 0) {
pkt = TAILQ_FIRST(&vxfer->pkts);
KASSERT(pkt != NULL);
vhci_pkt_destroy(sc, pkt);
@ -778,26 +835,29 @@ vhci_port_flush(vhci_softc_t *sc, vhci_port_t *port)
TAILQ_INIT(&vxferlist);
/* Drop all the packets in the H->U direction. */
pktlist = &port->pkts_device_ctrl.host_to_usb;
TAILQ_FOREACH_SAFE(pkt, pktlist, portlist, nxt) {
vxfer = (vhci_xfer_t *)pkt->xfer;
vxfer = pkt->vxfer;
KASSERT(vxfer->xfer.ux_status == USBD_IN_PROGRESS);
vhci_pkt_destroy(sc, pkt);
if (vxfer->refcnt == 0)
if (vxfer->npkts == 0)
TAILQ_INSERT_TAIL(&vxferlist, vxfer, freelist);
}
KASSERT(TAILQ_FIRST(pktlist) == NULL);
/* Drop all the packets in the U->H direction. */
pktlist = &port->pkts_device_ctrl.usb_to_host;
TAILQ_FOREACH_SAFE(pkt, pktlist, portlist, nxt) {
vxfer = (vhci_xfer_t *)pkt->xfer;
vxfer = pkt->vxfer;
KASSERT(vxfer->xfer.ux_status == USBD_IN_PROGRESS);
vhci_pkt_destroy(sc, pkt);
if (vxfer->refcnt == 0)
if (vxfer->npkts == 0)
TAILQ_INSERT_TAIL(&vxferlist, vxfer, freelist);
}
KASSERT(TAILQ_FIRST(pktlist) == NULL);
/* Terminate all the xfers collected. */
while ((vxfer = TAILQ_FIRST(&vxferlist)) != NULL) {
struct usbd_xfer *xfer = &vxfer->xfer;
TAILQ_REMOVE(&vxferlist, vxfer, freelist);
@ -983,7 +1043,7 @@ vhci_fd_read(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred,
}
TAILQ_FOREACH_SAFE(pkt, pktlist, portlist, nxt) {
vxfer = (vhci_xfer_t *)pkt->xfer;
vxfer = pkt->vxfer;
buf = pkt->buf + pkt->cursor;
KASSERT(pkt->size >= pkt->cursor);
size = uimin(uio->uio_resid, pkt->size - pkt->cursor);
@ -1000,7 +1060,7 @@ vhci_fd_read(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred,
if (pkt->cursor == pkt->size) {
vhci_pkt_destroy(sc, pkt);
if (vxfer->refcnt == 0) {
if (vxfer->npkts == 0) {
TAILQ_INSERT_TAIL(&vxferlist, vxfer, freelist);
}
}
@ -1056,7 +1116,7 @@ vhci_fd_write(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred,
}
TAILQ_FOREACH_SAFE(pkt, pktlist, portlist, nxt) {
vxfer = (vhci_xfer_t *)pkt->xfer;
vxfer = pkt->vxfer;
buf = pkt->buf + pkt->cursor;
KASSERT(pkt->size >= pkt->cursor);
size = uimin(uio->uio_resid, pkt->size - pkt->cursor);
@ -1073,7 +1133,7 @@ vhci_fd_write(struct file *fp, off_t *offp, struct uio *uio, kauth_cred_t cred,
if (pkt->cursor == pkt->size) {
vhci_pkt_destroy(sc, pkt);
if (vxfer->refcnt == 0) {
if (vxfer->npkts == 0) {
TAILQ_INSERT_TAIL(&vxferlist, vxfer, freelist);
}
}