[Spice-devel] [PATCH spice-gtk v4 24/29] usb-backend: Rewrite USB emulation support
Christophe de Dinechin
christophe.de.dinechin at gmail.com
Tue Aug 27 10:40:27 UTC 2019
Frediano Ziglio writes:
> Make initialisation easier.
> Always initialise parser.
My spellchecker seems to choke on "initialise", suggests
"initialize" (maybe a UK/US difference).
> Initialise both parser and host during spice_usb_backend_channel_new.
> Support not having libusb context (no physical devices).
> Avoids too much state variables.
"Reduce number of state variables"?
Based on the code, I'd go as far as stating "Simplify state machine logic".
> parser is always initialised after creation making sure the state
> is consistent.
That seems redundant with "Always initialize parser".
> Use a single state variable, data flows into/from a single parser.
>
> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> ---
> 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,
(You seem to have used "initialize" with a "z" here)
> + USB_CHANNEL_STATE_HOST,
> + USB_CHANNEL_STATE_PARSER,
I can't say that "STATE_HOST" and "STATE_PARSER" make much sense to me.
Maybe something like "STATE_USBREDIRHOST" and "STATE_PARSING" or
"STATE_PARSER_ACTIVE"?
> +} 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;
Nice simplification!
Would it make sense to use "bool" for flags?
> 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) {
> + 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);
> + g_assert(count >= hello_size + 4);
> + 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;
Why return 0 and not just fall through?
If a write retry is necessary, could you add a comment explaining why?
Side comment: usbredir_write_callback used to be a mere wrapper around
spice_usbredir_write_callback. Now, it has a whole lot of logic in it.
Is it intentional, or should some of that logic be moved to shared code?
> }
> 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) {
--
Cheers,
Christophe de Dinechin (IRC c3d)
More information about the Spice-devel
mailing list