usb: split packet result into actual_length + status

Since with the ehci and xhci controllers a single packet can be larger
then maxpacketsize, it is possible for the result of a single packet
to be both having transferred some data as well as the transfer to have
an error.

An example would be an input transfer from a bulk endpoint successfully
receiving 1 or more maxpacketsize packets from the device, followed
by a packet signalling halt.

While already touching all the devices and controllers handle_packet /
handle_data / handle_control code, also change the return type of
these functions to void, solely storing the status in the packet. To
make the code paths for regular versus async packet handling more
uniform.

This patch unfortunately is somewhat invasive, since makeing the qemu
usb core deal with this requires changes everywhere. This patch only
prepares the usb core for this, all the hcd / device changes are done
in such a way that there are no functional changes.

This patch has been tested with uhci and ehci hcds, together with usb-audio,
usb-hid and usb-storage devices, as well as with usb-redir redirection
with a wide variety of real devices.

Note that there is usually no need to directly set packet->actual_length
form devices handle_data callback, as that is done by usb_packet_copy()

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 109 insertions, 100 deletions

diff --git a/hw/usb/core.c b/hw/usb/core.c
index ab37f6f7b8..52b53108cd 100644
--- a/hw/usb/core.c
+++ b/hw/usb/core.c
@@ -97,17 +97,17 @@ void usb_wakeup(USBEndpoint *ep)
 #define SETUP_STATE_ACK   3
 #define SETUP_STATE_PARAM 4
 
-static int do_token_setup(USBDevice *s, USBPacket *p)
+static void do_token_setup(USBDevice *s, USBPacket *p)
 {
     int request, value, index;
-    int ret = 0;
 
     if (p->iov.size != 8) {
-        return USB_RET_STALL;
+        p->status = USB_RET_STALL;
+        return;
     }
 
     usb_packet_copy(p, s->setup_buf, p->iov.size);
-    p->result = 0;
+    p->actual_length = 0;
     s->setup_len   = (s->setup_buf[7] << 8) | s->setup_buf[6];
     s->setup_index = 0;
 
@@ -116,24 +116,26 @@ static int do_token_setup(USBDevice *s, USBPacket *p)
     index   = (s->setup_buf[5] << 8) | s->setup_buf[4];
 
     if (s->setup_buf[0] & USB_DIR_IN) {
-        ret = usb_device_handle_control(s, p, request, value, index,
-                                        s->setup_len, s->data_buf);
-        if (ret == USB_RET_ASYNC) {
-             s->setup_state = SETUP_STATE_SETUP;
-             return USB_RET_ASYNC;
+        usb_device_handle_control(s, p, request, value, index,
+                                  s->setup_len, s->data_buf);
+        if (p->status == USB_RET_ASYNC) {
+            s->setup_state = SETUP_STATE_SETUP;
+        }
+        if (p->status != USB_RET_SUCCESS) {
+            return;
         }
-        if (ret < 0)
-            return ret;
 
-        if (ret < s->setup_len)
-            s->setup_len = ret;
+        if (p->actual_length < s->setup_len) {
+            s->setup_len = p->actual_length;
+        }
         s->setup_state = SETUP_STATE_DATA;
     } else {
         if (s->setup_len > sizeof(s->data_buf)) {
             fprintf(stderr,
                 "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
                 s->setup_len, sizeof(s->data_buf));
-            return USB_RET_STALL;
+            p->status = USB_RET_STALL;
+            return;
         }
         if (s->setup_len == 0)
             s->setup_state = SETUP_STATE_ACK;
@@ -141,13 +143,12 @@ static int do_token_setup(USBDevice *s, USBPacket *p)
             s->setup_state = SETUP_STATE_DATA;
     }
 
-    return ret;
+    p->actual_length = 8;
 }
 
-static int do_token_in(USBDevice *s, USBPacket *p)
+static void do_token_in(USBDevice *s, USBPacket *p)
 {
     int request, value, index;
-    int ret = 0;
 
     assert(p->ep->nr == 0);
 
@@ -158,19 +159,15 @@ static int do_token_in(USBDevice *s, USBPacket *p)
     switch(s->setup_state) {
     case SETUP_STATE_ACK:
         if (!(s->setup_buf[0] & USB_DIR_IN)) {
-            ret = usb_device_handle_control(s, p, request, value, index,
-                                            s->setup_len, s->data_buf);
-            if (ret == USB_RET_ASYNC) {
-                return USB_RET_ASYNC;
+            usb_device_handle_control(s, p, request, value, index,
+                                      s->setup_len, s->data_buf);
+            if (p->status == USB_RET_ASYNC) {
+                return;
             }
             s->setup_state = SETUP_STATE_IDLE;
-            if (ret > 0)
-                return 0;
-            return ret;
+            p->actual_length = 0;
         }
-
-        /* return 0 byte */
-        return 0;
+        break;
 
     case SETUP_STATE_DATA:
         if (s->setup_buf[0] & USB_DIR_IN) {
@@ -180,20 +177,21 @@ static int do_token_in(USBDevice *s, USBPacket *p)
             }
             usb_packet_copy(p, s->data_buf + s->setup_index, len);
             s->setup_index += len;
-            if (s->setup_index >= s->setup_len)
+            if (s->setup_index >= s->setup_len) {
                 s->setup_state = SETUP_STATE_ACK;
-            return len;
+            }
+            return;
         }
-
         s->setup_state = SETUP_STATE_IDLE;
-        return USB_RET_STALL;
+        p->status = USB_RET_STALL;
+        break;
 
     default:
-        return USB_RET_STALL;
+        p->status = USB_RET_STALL;
     }
 }
 
-static int do_token_out(USBDevice *s, USBPacket *p)
+static void do_token_out(USBDevice *s, USBPacket *p)
 {
     assert(p->ep->nr == 0);
 
@@ -205,7 +203,7 @@ static int do_token_out(USBDevice *s, USBPacket *p)
         } else {
             /* ignore additional output */
         }
-        return 0;
+        break;
 
     case SETUP_STATE_DATA:
         if (!(s->setup_buf[0] & USB_DIR_IN)) {
@@ -215,23 +213,23 @@ static int do_token_out(USBDevice *s, USBPacket *p)
             }
             usb_packet_copy(p, s->data_buf + s->setup_index, len);
             s->setup_index += len;
-            if (s->setup_index >= s->setup_len)
+            if (s->setup_index >= s->setup_len) {
                 s->setup_state = SETUP_STATE_ACK;
-            return len;
+            }
+            return;
         }
-
         s->setup_state = SETUP_STATE_IDLE;
-        return USB_RET_STALL;
+        p->status = USB_RET_STALL;
+        break;
 
     default:
-        return USB_RET_STALL;
+        p->status = USB_RET_STALL;
     }
 }
 
-static int do_parameter(USBDevice *s, USBPacket *p)
+static void do_parameter(USBDevice *s, USBPacket *p)
 {
-    int request, value, index;
-    int i, ret = 0;
+    int i, request, value, index;
 
     for (i = 0; i < 8; i++) {
         s->setup_buf[i] = p->parameter >> (i*8);
@@ -249,27 +247,27 @@ static int do_parameter(USBDevice *s, USBPacket *p)
         fprintf(stderr,
                 "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
                 s->setup_len, sizeof(s->data_buf));
-        return USB_RET_STALL;
+        p->status = USB_RET_STALL;
+        return;
     }
 
     if (p->pid == USB_TOKEN_OUT) {
         usb_packet_copy(p, s->data_buf, s->setup_len);
     }
 
-    ret = usb_device_handle_control(s, p, request, value, index,
-                                    s->setup_len, s->data_buf);
-    if (ret < 0) {
-        return ret;
+    usb_device_handle_control(s, p, request, value, index,
+                              s->setup_len, s->data_buf);
+    if (p->status == USB_RET_ASYNC) {
+        return;
     }
 
-    if (ret < s->setup_len) {
-        s->setup_len = ret;
+    if (p->actual_length < s->setup_len) {
+        s->setup_len = p->actual_length;
     }
     if (p->pid == USB_TOKEN_IN) {
+        p->actual_length = 0;
         usb_packet_copy(p, s->data_buf, s->setup_len);
     }
-
-    return ret;
 }
 
 /* ctrl complete function for devices which use usb_generic_handle_packet and
@@ -278,30 +276,30 @@ static int do_parameter(USBDevice *s, USBPacket *p)
    usb_packet_complete to complete their async control packets. */
 void usb_generic_async_ctrl_complete(USBDevice *s, USBPacket *p)
 {
-    if (p->result < 0) {
+    if (p->status < 0) {
         s->setup_state = SETUP_STATE_IDLE;
     }
 
     switch (s->setup_state) {
     case SETUP_STATE_SETUP:
-        if (p->result < s->setup_len) {
-            s->setup_len = p->result;
+        if (p->actual_length < s->setup_len) {
+            s->setup_len = p->actual_length;
         }
         s->setup_state = SETUP_STATE_DATA;
-        p->result = 8;
+        p->actual_length = 8;
         break;
 
     case SETUP_STATE_ACK:
         s->setup_state = SETUP_STATE_IDLE;
-        p->result = 0;
+        p->actual_length = 0;
         break;
 
     case SETUP_STATE_PARAM:
-        if (p->result < s->setup_len) {
-            s->setup_len = p->result;
+        if (p->actual_length < s->setup_len) {
+            s->setup_len = p->actual_length;
         }
         if (p->pid == USB_TOKEN_IN) {
-            p->result = 0;
+            p->actual_length = 0;
             usb_packet_copy(p, s->data_buf, s->setup_len);
         }
         break;
@@ -342,40 +340,57 @@ USBDevice *usb_find_device(USBPort *port, uint8_t addr)
     return usb_device_find_device(dev, addr);
 }
 
-static int usb_process_one(USBPacket *p)
+static void usb_process_one(USBPacket *p)
 {
     USBDevice *dev = p->ep->dev;
 
+    /*
+     * Handlers expect status to be initialized to USB_RET_SUCCESS, but it
+     * can be USB_RET_NAK here from a previous usb_process_one() call,
+     * or USB_RET_ASYNC from going through usb_queue_one().
+     */
+    p->status = USB_RET_SUCCESS;
+
     if (p->ep->nr == 0) {
         /* control pipe */
         if (p->parameter) {
-            return do_parameter(dev, p);
+            do_parameter(dev, p);
+            return;
         }
         switch (p->pid) {
         case USB_TOKEN_SETUP:
-            return do_token_setup(dev, p);
+            do_token_setup(dev, p);
+            break;
         case USB_TOKEN_IN:
-            return do_token_in(dev, p);
+            do_token_in(dev, p);
+            break;
         case USB_TOKEN_OUT:
-            return do_token_out(dev, p);
+            do_token_out(dev, p);
+            break;
         default:
-            return USB_RET_STALL;
+            p->status = USB_RET_STALL;
         }
     } else {
         /* data pipe */
-        return usb_device_handle_data(dev, p);
+        usb_device_handle_data(dev, p);
     }
 }
 
-/* Hand over a packet to a device for processing.  Return value
+static void usb_queue_one(USBPacket *p)
+{
+    usb_packet_set_state(p, USB_PACKET_QUEUED);
+    QTAILQ_INSERT_TAIL(&p->ep->queue, p, queue);
+    p->status = USB_RET_ASYNC;
+}
+
+/* Hand over a packet to a device for processing.  p->status ==
    USB_RET_ASYNC indicates the processing isn't finished yet, the
    driver will call usb_packet_complete() when done processing it. */
-int usb_handle_packet(USBDevice *dev, USBPacket *p)
+void usb_handle_packet(USBDevice *dev, USBPacket *p)
 {
-    int ret;
-
     if (dev == NULL) {
-        return USB_RET_NODEV;
+        p->status = USB_RET_NODEV;
+        return;
     }
     assert(dev == p->ep->dev);
     assert(dev->state == USB_STATE_DEFAULT);
@@ -389,32 +404,26 @@ int usb_handle_packet(USBDevice *dev, USBPacket *p)
     }
 
     if (QTAILQ_EMPTY(&p->ep->queue) || p->ep->pipeline) {
-        ret = usb_process_one(p);
-        if (ret == USB_RET_ASYNC) {
+        usb_process_one(p);
+        if (p->status == USB_RET_ASYNC) {
             assert(p->ep->type != USB_ENDPOINT_XFER_ISOC);
             usb_packet_set_state(p, USB_PACKET_ASYNC);
             QTAILQ_INSERT_TAIL(&p->ep->queue, p, queue);
-        } else if (ret == USB_RET_ADD_TO_QUEUE) {
-            usb_packet_set_state(p, USB_PACKET_QUEUED);
-            QTAILQ_INSERT_TAIL(&p->ep->queue, p, queue);
-            ret = USB_RET_ASYNC;
+        } else if (p->status == USB_RET_ADD_TO_QUEUE) {
+            usb_queue_one(p);
         } else {
             /*
              * When pipelining is enabled usb-devices must always return async,
              * otherwise packets can complete out of order!
              */
             assert(!p->ep->pipeline || QTAILQ_EMPTY(&p->ep->queue));
-            if (ret != USB_RET_NAK) {
-                p->result = ret;
+            if (p->status != USB_RET_NAK) {
                 usb_packet_set_state(p, USB_PACKET_COMPLETE);
             }
         }
     } else {
-        ret = USB_RET_ASYNC;
-        usb_packet_set_state(p, USB_PACKET_QUEUED);
-        QTAILQ_INSERT_TAIL(&p->ep->queue, p, queue);
+        usb_queue_one(p);
     }
-    return ret;
 }
 
 void usb_packet_complete_one(USBDevice *dev, USBPacket *p)
@@ -422,9 +431,10 @@ void usb_packet_complete_one(USBDevice *dev, USBPacket *p)
     USBEndpoint *ep = p->ep;
 
     assert(QTAILQ_FIRST(&ep->queue) == p);
-    assert(p->result != USB_RET_ASYNC && p->result != USB_RET_NAK);
+    assert(p->status != USB_RET_ASYNC && p->status != USB_RET_NAK);
 
-    if (p->result < 0 || (p->short_not_ok && (p->result < p->iov.size))) {
+    if (p->status != USB_RET_SUCCESS ||
+            (p->short_not_ok && (p->actual_length < p->iov.size))) {
         ep->halted = true;
     }
     usb_packet_set_state(p, USB_PACKET_COMPLETE);
@@ -438,7 +448,6 @@ void usb_packet_complete_one(USBDevice *dev, USBPacket *p)
 void usb_packet_complete(USBDevice *dev, USBPacket *p)
 {
     USBEndpoint *ep = p->ep;
-    int ret;
 
     usb_packet_check_state(p, USB_PACKET_ASYNC);
     usb_packet_complete_one(dev, p);
@@ -447,7 +456,7 @@ void usb_packet_complete(USBDevice *dev, USBPacket *p)
         p = QTAILQ_FIRST(&ep->queue);
         if (ep->halted) {
             /* Empty the queue on a halt */
-            p->result = USB_RET_REMOVE_FROM_QUEUE;
+            p->status = USB_RET_REMOVE_FROM_QUEUE;
             dev->port->ops->complete(dev->port, p);
             continue;
         }
@@ -455,12 +464,11 @@ void usb_packet_complete(USBDevice *dev, USBPacket *p)
             break;
         }
         usb_packet_check_state(p, USB_PACKET_QUEUED);
-        ret = usb_process_one(p);
-        if (ret == USB_RET_ASYNC) {
+        usb_process_one(p);
+        if (p->status == USB_RET_ASYNC) {
             usb_packet_set_state(p, USB_PACKET_ASYNC);
             break;
         }
-        p->result = ret;
         usb_packet_complete_one(ep->dev, p);
     }
 }
@@ -541,7 +549,8 @@ void usb_packet_setup(USBPacket *p, int pid, USBEndpoint *ep, uint64_t id,
     p->id = id;
     p->pid = pid;
     p->ep = ep;
-    p->result = 0;
+    p->status = USB_RET_SUCCESS;
+    p->actual_length = 0;
     p->parameter = 0;
     p->short_not_ok = short_not_ok;
     p->int_req = int_req;
@@ -557,31 +566,31 @@ void usb_packet_addbuf(USBPacket *p, void *ptr, size_t len)
 
 void usb_packet_copy(USBPacket *p, void *ptr, size_t bytes)
 {
-    assert(p->result >= 0);
-    assert(p->result + bytes <= p->iov.size);
+    assert(p->actual_length >= 0);
+    assert(p->actual_length + bytes <= p->iov.size);
     switch (p->pid) {
     case USB_TOKEN_SETUP:
     case USB_TOKEN_OUT:
-        iov_to_buf(p->iov.iov, p->iov.niov, p->result, ptr, bytes);
+        iov_to_buf(p->iov.iov, p->iov.niov, p->actual_length, ptr, bytes);
         break;
     case USB_TOKEN_IN:
-        iov_from_buf(p->iov.iov, p->iov.niov, p->result, ptr, bytes);
+        iov_from_buf(p->iov.iov, p->iov.niov, p->actual_length, ptr, bytes);
         break;
     default:
         fprintf(stderr, "%s: invalid pid: %x\n", __func__, p->pid);
         abort();
     }
-    p->result += bytes;
+    p->actual_length += bytes;
 }
 
 void usb_packet_skip(USBPacket *p, size_t bytes)
 {
-    assert(p->result >= 0);
-    assert(p->result + bytes <= p->iov.size);
+    assert(p->actual_length >= 0);
+    assert(p->actual_length + bytes <= p->iov.size);
     if (p->pid == USB_TOKEN_IN) {
-        iov_memset(p->iov.iov, p->iov.niov, p->result, 0, bytes);
+        iov_memset(p->iov.iov, p->iov.niov, p->actual_length, 0, bytes);
     }
-    p->result += bytes;
+    p->actual_length += bytes;
 }
 
 void usb_packet_cleanup(USBPacket *p)