Re: [PATCH spice-gtk v4 24/29] usb-backend: Rewrite USB emulation support

[Uri Lublin <uril@xxxxxxxxxx>]

Hi,

On 8/27/19 12:22 PM, Frediano Ziglio wrote:
> Make initialisation easier.
> Always initialise parser.
> Initialise both parser and host during spice_usb_backend_channel_new.
> Support not having libusb context (no physical devices).
> Avoids too much state variables.
> parser is always initialised after creation making sure the state
> is consistent.

If usbredirhost is used, why is there a need for a parser too ?
Also below in initialize_parser there is a check that
ch->usbredirhost is NULL (possibly because the parser is always
being initialized before the host).

> Use a single state variable, data flows into/from a single parser.
>
> Signed-off-by: Frediano Ziglio <fziglio@xxxxxxxxxx>
> ---
>   src/usb-backend.c | 236 +++++++++++++++++++++++-----------------------
>   1 file changed, 116 insertions(+), 120 deletions(-)
>
> diff --git a/src/usb-backend.c b/src/usb-backend.c
> index 36a73a89..d614e693 100644
> --- a/src/usb-backend.c
> +++ b/src/usb-backend.c
> @@ -78,21 +78,21 @@ struct _SpiceUsbBackend
>       uint32_t own_devices_mask;
>   };
>   
> +typedef enum {
> +    USB_CHANNEL_STATE_INITIALIZING,
> +    USB_CHANNEL_STATE_HOST,
> +    USB_CHANNEL_STATE_PARSER,
> +} SpiceUsbBackendChannelState;
> +
>   struct _SpiceUsbBackendChannel
>   {
>       struct usbredirhost *usbredirhost;
> -    struct usbredirhost *hidden_host;
>       struct usbredirparser *parser;
> -    struct usbredirparser *hidden_parser;
> +    SpiceUsbBackendChannelState state;
>       uint8_t *read_buf;
>       int read_buf_size;
>       struct usbredirfilter_rule *rules;
>       int rules_count;
> -    uint32_t host_caps;
> -    uint32_t parser_init_done  : 1;
> -    uint32_t parser_with_hello : 1;
> -    uint32_t hello_done_parser : 1;
> -    uint32_t hello_sent        : 1;
>       uint32_t rejected          : 1;
>       uint32_t wait_disconnect_ack : 1;
>       SpiceUsbBackendDevice *attached;
> @@ -405,15 +405,16 @@ from both the main thread as well as from the usb event handling thread */
>   static void usbredir_write_flush_callback(void *user_data)
>   {
>       SpiceUsbBackendChannel *ch = user_data;
> +    if (ch->parser == NULL) {
> +        return;
> +    }
>       if (is_channel_ready(ch->user_data)) {
> -        if (ch->usbredirhost) {

Do you need the following g_assert, or is the ch->parser==NULL enough
   g_assert(ch->state != USB_CHANNEL_STATE_INITIALIZING);

> +        if (ch->state == USB_CHANNEL_STATE_HOST) {
>               SPICE_DEBUG("%s ch %p -> usbredirhost", __FUNCTION__, ch);
>               usbredirhost_write_guest_data(ch->usbredirhost);
> -        } else if (ch->parser) {
> +        } else {
>               SPICE_DEBUG("%s ch %p -> parser", __FUNCTION__, ch);
>               usbredirparser_do_write(ch->parser);
> -        } else {
> -            SPICE_DEBUG("%s ch %p (NOT ACTIVE)", __FUNCTION__, ch);
>           }
>       } else {
>           SPICE_DEBUG("%s ch %p (not ready)", __FUNCTION__, ch);
> @@ -673,21 +674,42 @@ static void usbredir_log(void *user_data, int level, const char *msg)
>       }
>   }
>   
> +static struct usbredirparser *create_parser(SpiceUsbBackendChannel *ch);
> +
>   static int usbredir_write_callback(void *user_data, uint8_t *data, int count)
>   {
>       SpiceUsbBackendChannel *ch = user_data;
>       int res;
>       SPICE_DEBUG("%s ch %p, %d bytes", __FUNCTION__, ch, count);
> -    if (!ch->hello_sent) {
> -        /* hello is short header (12) + hello struct (64) + capabilities (4) */
> -        int hello_size = sizeof(struct usb_redir_header) + sizeof(struct usb_redir_hello_header);
> -        ch->hello_sent = 1;
> -        if (count == hello_size) {
> -            memcpy(&ch->host_caps, data + hello_size - sizeof(ch->host_caps),
> -                   sizeof(ch->host_caps));
> -            SPICE_DEBUG("%s ch %p, sending first hello, caps %08X",
> -                        __FUNCTION__, ch, ch->host_caps);
> +
> +    // handle first packet (HELLO) creating parser from capabilities
> +    if (SPICE_UNLIKELY(ch->parser == NULL)) {
> +        // we are still initializing the host
> +        if (ch->usbredirhost == NULL) {
> +            return 0;
>           }
> +
> +        ch->parser = create_parser(ch);
> +        if (!ch->parser) {
> +            return 0;
> +        }
> +
> +        /* hello is short header (12) + hello struct (64) */
> +        const int hello_size = 12 + sizeof(struct usb_redir_hello_header);

sizeof(struct usb_redir_header) instead of 12 (and btw it's 16)

> +        g_assert(count >= hello_size + 4);

nit: Maybe replace 4 with
  const size_t caps_size = sizeof(uint32_t) * USB_REDIR_CAPS_SIZE;
  g_assert(count >= hello_size + caps_size);


Uri.

> +        g_assert(SPICE_ALIGNED_CAST(struct usb_redir_header *, data)->type == usb_redir_hello);
> +
> +        const uint32_t flags =
> +            usbredirparser_fl_write_cb_owns_buffer | usbredirparser_fl_usb_host |
> +            usbredirparser_fl_no_hello;
> +
> +        usbredirparser_init(ch->parser,
> +                            PACKAGE_STRING,
> +                            SPICE_ALIGNED_CAST(uint32_t *, data + hello_size),
> +                            (count - hello_size) / sizeof(uint32_t),
> +                            flags);
> +
> +        return 0;
>       }
>       res = spice_usbredir_write_callback(ch->user_data, data, count);
>       return res;
> @@ -707,31 +729,33 @@ int spice_usb_backend_read_guest_data(SpiceUsbBackendChannel *ch, uint8_t *data,
>   
>       ch->read_buf = data;
>       ch->read_buf_size = count;
> -    if (ch->usbredirhost) {
> -        res = usbredirhost_read_guest_data(ch->usbredirhost);
> -        if (!ch->hello_done_parser) {
> -            int res_parser;
> +    if (SPICE_UNLIKELY(ch->state == USB_CHANNEL_STATE_INITIALIZING)) {
> +        if (ch->usbredirhost != NULL) {
> +            res = usbredirhost_read_guest_data(ch->usbredirhost);
> +            if (res != 0) {
> +                return res;
> +            }
> +            ch->state = USB_CHANNEL_STATE_HOST;
> +
>               /* usbredirhost should consume hello response */
>               g_return_val_if_fail(ch->read_buf == NULL, USB_REDIR_ERROR_READ_PARSE);
> +        } else {
> +            ch->state = USB_CHANNEL_STATE_PARSER;
> +        }
>   
> -            ch->read_buf = data;
> -            ch->read_buf_size = count;
> -            ch->hello_done_parser = 1;
> -            if (ch->attached && ch->attached->edev) {
> -                /* case of CD sharing on connect */
> -                ch->usbredirhost = NULL;
> -                ch->parser = ch->hidden_parser;
> -                SPICE_DEBUG("%s: switch %p to parser", __FUNCTION__, ch);
> -            }
> -            res_parser = usbredirparser_do_read(ch->hidden_parser);
> -            if (res >= 0) {
> -                res = res_parser;
> -            }
> +        ch->read_buf = data;
> +        ch->read_buf_size = count;
> +        if (ch->attached && ch->attached->edev) {
> +            /* case of CD sharing on connect */
> +            ch->state = USB_CHANNEL_STATE_PARSER;
> +            SPICE_DEBUG("%s: switch %p to parser", __FUNCTION__, ch);
>           }
> -    } else if (ch->parser) {
> -        res = usbredirparser_do_read(ch->parser);
> +        return usbredirparser_do_read(ch->parser);
> +    }
> +    if (ch->state == USB_CHANNEL_STATE_HOST) {
> +        res = usbredirhost_read_guest_data(ch->usbredirhost);
>       } else {
> -        res = USB_REDIR_ERROR_IO;
> +        res = usbredirparser_do_read(ch->parser);
>       }
>       switch (res)
>       {
> @@ -783,14 +807,12 @@ GError *spice_usb_backend_get_error_details(int error_code, gchar *desc)
>   
>   void spice_usb_backend_return_write_data(SpiceUsbBackendChannel *ch, void *data)
>   {
> -    if (ch->usbredirhost) {
> +    if (ch->state == USB_CHANNEL_STATE_HOST) {
>           SPICE_DEBUG("%s ch %p -> usbredirhost", __FUNCTION__, ch);
>           usbredirhost_free_write_buffer(ch->usbredirhost, data);
> -    } else if (ch->parser) {
> +    } else {
>           SPICE_DEBUG("%s ch %p -> parser", __FUNCTION__, ch);
>           usbredirparser_free_write_buffer(ch->parser, data);
> -    } else {
> -        SPICE_DEBUG("%s ch %p - NOBODY TO CALL", __FUNCTION__, ch);
>       }
>   }
>   
> @@ -1005,10 +1027,10 @@ static void usbredir_device_disconnect_ack(void *priv)
>   {
>       SpiceUsbBackendChannel *ch = priv;
>       SPICE_DEBUG("%s ch %p", __FUNCTION__, ch);
> -    if (ch->parser && ch->wait_disconnect_ack) {
> -        ch->parser = NULL;
> +    if (ch->state == USB_CHANNEL_STATE_PARSER && ch->usbredirhost != NULL &&
> +        ch->wait_disconnect_ack) {
> +        ch->state = USB_CHANNEL_STATE_HOST;
>           SPICE_DEBUG("%s switch to usbredirhost", __FUNCTION__);
> -        ch->usbredirhost = ch->hidden_host;
>       }
>       ch->wait_disconnect_ack = 0;
>   }
> @@ -1027,9 +1049,6 @@ usbredir_hello(void *priv, struct usb_redir_hello_header *hello)
>       SPICE_DEBUG("%s %p %sattached %s", __FUNCTION__, ch,
>           edev ? "" : "not ",  hello ? "" : "(internal)");
>   
> -    if (hello) {
> -        ch->hello_done_parser = 1;
> -    }
>       if (!edev) {
>           return;
>       }
> @@ -1079,53 +1098,24 @@ usbredir_hello(void *priv, struct usb_redir_hello_header *hello)
>       usbredir_write_flush_callback(ch);
>   }
>   
> -static void initialize_parser(SpiceUsbBackendChannel *ch, gboolean do_hello)
> +static void initialize_parser(SpiceUsbBackendChannel *ch)
>   {
>       uint32_t flags, caps[USB_REDIR_CAPS_SIZE] = { 0 };
>   
> -    g_return_if_fail(ch->hidden_parser != NULL);
> -    if (ch->parser_init_done) {
> -        if (ch->parser_with_hello != do_hello) {
> -            g_return_if_reached();
> -        }
> -        return;
> -    }
> +    g_assert(ch->usbredirhost == NULL);
>   
> -    ch->parser_init_done = 1;
> -    ch->parser_with_hello = do_hello;
>       flags = usbredirparser_fl_write_cb_owns_buffer | usbredirparser_fl_usb_host;
>   
> -    if (do_hello) {
> -        ch->hello_sent = 1;
> -        ch->host_caps |= 1 << usb_redir_cap_connect_device_version;
> -        ch->host_caps |= 1 << usb_redir_cap_device_disconnect_ack;
> -        ch->host_caps |= 1 << usb_redir_cap_ep_info_max_packet_size;
> -        ch->host_caps |= 1 << usb_redir_cap_64bits_ids;
> -        ch->host_caps |= 1 << usb_redir_cap_32bits_bulk_length;
> -    } else {
> -        flags |= usbredirparser_fl_no_hello;
> -    }
> -
> -    if (ch->host_caps & (1 << usb_redir_cap_connect_device_version)) {
> -        usbredirparser_caps_set_cap(caps, usb_redir_cap_connect_device_version);
> -    }
> +    usbredirparser_caps_set_cap(caps, usb_redir_cap_connect_device_version);
>       usbredirparser_caps_set_cap(caps, usb_redir_cap_filter);
> -    if (ch->host_caps & (1 << usb_redir_cap_device_disconnect_ack)) {
> -        usbredirparser_caps_set_cap(caps, usb_redir_cap_device_disconnect_ack);
> -    }
> -    if (ch->host_caps & (1 << usb_redir_cap_ep_info_max_packet_size)) {
> -        usbredirparser_caps_set_cap(caps, usb_redir_cap_ep_info_max_packet_size);
> -    }
> -    if (ch->host_caps & (1 << usb_redir_cap_64bits_ids)) {
> -        usbredirparser_caps_set_cap(caps, usb_redir_cap_64bits_ids);
> -    }
> -    if (ch->host_caps & (1 << usb_redir_cap_32bits_bulk_length)) {
> -        usbredirparser_caps_set_cap(caps, usb_redir_cap_32bits_bulk_length);
> -    }
> -    if (ch->host_caps & (1 << usb_redir_cap_bulk_streams)) {
> -        usbredirparser_caps_set_cap(caps, usb_redir_cap_bulk_streams);
> -    }
> -    usbredirparser_init(ch->hidden_parser, PACKAGE_STRING, caps, USB_REDIR_CAPS_SIZE, flags);
> +    usbredirparser_caps_set_cap(caps, usb_redir_cap_device_disconnect_ack);
> +    usbredirparser_caps_set_cap(caps, usb_redir_cap_ep_info_max_packet_size);
> +    usbredirparser_caps_set_cap(caps, usb_redir_cap_64bits_ids);
> +    usbredirparser_caps_set_cap(caps, usb_redir_cap_32bits_bulk_length);
> +    usbredirparser_caps_set_cap(caps, usb_redir_cap_bulk_receiving);
> +    usbredirparser_caps_set_cap(caps, usb_redir_cap_bulk_streams);
> +
> +    usbredirparser_init(ch->parser, PACKAGE_STRING, caps, USB_REDIR_CAPS_SIZE, flags);
>   }
>   
>   /*
> @@ -1180,7 +1170,7 @@ static gboolean attach_edev(SpiceUsbBackendChannel *ch,
>              _("Failed to redirect device %d"), 1);
>           return FALSE;
>       }
> -    if (ch->usbredirhost && !ch->hello_done_parser) {
> +    if (ch->state == USB_CHANNEL_STATE_INITIALIZING) {
>           /*
>               we can't initialize parser until we see hello from usbredir
>               and the parser can't work until it sees the hello response.
> @@ -1190,15 +1180,13 @@ static gboolean attach_edev(SpiceUsbBackendChannel *ch,
>           SPICE_DEBUG("%s waiting until the channel is ready", __FUNCTION__);
>   
>       } else {
> -        initialize_parser(ch, ch->hidden_host == NULL);
> -        ch->usbredirhost = NULL;
> -        ch->parser = ch->hidden_parser;
> +        ch->state = USB_CHANNEL_STATE_PARSER;
>       }
>       ch->wait_disconnect_ack = 0;
>       ch->attached = dev;
>       dev->attached_to = ch;
> -    device_ops(dev->edev)->attach(dev->edev, ch->hidden_parser);
> -    if (ch->hello_done_parser) {
> +    device_ops(dev->edev)->attach(dev->edev, ch->parser);
> +    if (ch->state == USB_CHANNEL_STATE_PARSER) {
>           /* send device info */
>           usbredir_hello(ch, NULL);
>       }
> @@ -1218,9 +1206,15 @@ gboolean spice_usb_backend_channel_attach(SpiceUsbBackendChannel *ch,
>           return attach_edev(ch, dev, error);
>       }
>   
> +    // no physical device enabled
> +    if (ch->usbredirhost == NULL) {
> +        return FALSE;
> +    }
> +
>       libusb_device_handle *handle = NULL;
> -    ch->usbredirhost = ch->hidden_host;
> -    ch->parser = NULL;
> +    if (ch->state != USB_CHANNEL_STATE_INITIALIZING) {
> +        ch->state = USB_CHANNEL_STATE_HOST;
> +    }
>   
>       /*
>          Under Windows we need to avoid updating
> @@ -1261,10 +1255,10 @@ void spice_usb_backend_channel_detach(SpiceUsbBackendChannel *ch)
>           SPICE_DEBUG("%s: nothing to detach", __FUNCTION__);
>           return;
>       }
> -    if (ch->usbredirhost) {
> +    if (ch->state == USB_CHANNEL_STATE_HOST) {
>           /* it will call libusb_close internally */
>           usbredirhost_set_device(ch->usbredirhost, NULL);
> -    } else if (ch->parser) {
> +    } else {
>           if (edev) {
>               device_ops(edev)->detach(edev);
>           }
> @@ -1272,9 +1266,8 @@ void spice_usb_backend_channel_detach(SpiceUsbBackendChannel *ch)
>           usbredir_write_flush_callback(ch);
>           ch->wait_disconnect_ack =
>               usbredirparser_peer_has_cap(ch->parser, usb_redir_cap_device_disconnect_ack);
> -        if (!ch->wait_disconnect_ack) {
> -            ch->usbredirhost = ch->hidden_host;
> -            ch->parser = NULL;
> +        if (!ch->wait_disconnect_ack && ch->usbredirhost != NULL) {
> +            ch->state = USB_CHANNEL_STATE_HOST;
>           }
>       }
>       SPICE_DEBUG("%s ch %p, detach done", __FUNCTION__, ch);
> @@ -1311,16 +1304,22 @@ SpiceUsbBackendChannel *spice_usb_backend_channel_new(SpiceUsbBackend *be,
>                                           usbredirparser_warning,
>                                      usbredirhost_fl_write_cb_owns_buffer);
>           g_warn_if_fail(ch->usbredirhost != NULL);
> +        if (ch->usbredirhost != NULL) {
> +            usbredirhost_set_buffered_output_size_cb(ch->usbredirhost,
> +                                                     usbredir_buffered_output_size_callback);
> +            // force flush of HELLO packet and creation of parser
> +            usbredirhost_write_guest_data(ch->usbredirhost);
> +        }
> +    } else {
> +        // no physical device support, only emulated, create the
> +        // parser
> +        ch->parser = create_parser(ch);
> +        if (ch->parser != NULL) {
> +            initialize_parser(ch);
> +        }
>       }
>   
> -    if (ch->usbredirhost) {
> -        ch->hidden_parser = create_parser(ch);
> -        ch->hidden_host = ch->usbredirhost;
> -        usbredirhost_set_buffered_output_size_cb(ch->usbredirhost,
> -                                                 usbredir_buffered_output_size_callback);
> -    }
> -
> -    if (!ch->hidden_parser) {
> +    if (!ch->parser) {
>           spice_usb_backend_channel_delete(ch);
>           ch = NULL;
>       }
> @@ -1332,12 +1331,9 @@ SpiceUsbBackendChannel *spice_usb_backend_channel_new(SpiceUsbBackend *be,
>   void spice_usb_backend_channel_flush_writes(SpiceUsbBackendChannel *ch)
>   {
>       SPICE_DEBUG("%s %p is up", __FUNCTION__, ch);
> -    if (ch->usbredirhost) {
> +    if (ch->state != USB_CHANNEL_STATE_PARSER && ch->usbredirhost != NULL) {
>           usbredirhost_write_guest_data(ch->usbredirhost);
> -        initialize_parser(ch, FALSE);
>       } else {
> -        initialize_parser(ch, TRUE);
> -        ch->parser = ch->hidden_parser;
>           usbredirparser_do_write(ch->parser);
>       }
>   }
> @@ -1348,11 +1344,11 @@ void spice_usb_backend_channel_delete(SpiceUsbBackendChannel *ch)
>       if (!ch) {
>           return;
>       }
> -    if (ch->hidden_host) {
> -        usbredirhost_close(ch->hidden_host);
> +    if (ch->usbredirhost) {
> +        usbredirhost_close(ch->usbredirhost);
>       }
> -    if (ch->hidden_parser) {
> -        usbredirparser_destroy(ch->hidden_parser);
> +    if (ch->parser) {
> +        usbredirparser_destroy(ch->parser);
>       }
>   
>       if (ch->rules) {
> @@ -1372,7 +1368,7 @@ spice_usb_backend_channel_get_guest_filter(SpiceUsbBackendChannel *ch,
>       int i;
>       *r = NULL;
>       *count = 0;
> -    if (ch->usbredirhost) {
> +    if (ch->usbredirhost != NULL) {
>           usbredirhost_get_guest_filter(ch->usbredirhost, r, count);
>       }
>       if (*r == NULL) {

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