From f5e24c5cf77b92ab2737eb230db7ae0b2fb102cc Mon Sep 17 00:00:00 2001

From: Frediano Ziglio <freddy77@gmail.com>

Date: Sat, 17 Sep 2022 09:28:08 +0100

Subject: [PATCH 5/8] Recreate watch if needed

Do not always watch for output buffer.

Watching for output buffer if we don't have nothing to write

(which is the usual case) is consuming a lot of CPU.

This fixes https://gitlab.freedesktop.org/spice/usbredir/-/issues/24.

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>

---

 tools/usbredirect.c | 28 ++++++++++++++++++++++++++--

 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/tools/usbredirect.c b/tools/usbredirect.c

index 6a8b68b..b6a30ad 100644

--- a/tools/usbredirect.c

+++ b/tools/usbredirect.c

@@ -29,6 +29,7 @@ typedef struct redirect {

     } device;

     bool is_client;

     bool keepalive;

+    bool watch_inout;

     char *addr;

     int port;

     int verbosity;

@@ -42,6 +43,8 @@ typedef struct redirect {

     GMainLoop *main_loop;

 } redirect;

+static void create_watch(redirect *self);

+

 static bool

 parse_opt_device(const char *device, int *vendor, int *product)

 {

@@ -162,6 +165,7 @@ parse_opts(int *argc, char ***argv)

     }

     self = g_new0(redirect, 1);

+    self->watch_inout = true;

     if (!parse_opt_device(device, &self->device.vendor, &self->device.product)) {

         g_printerr("Failed to parse device: '%s' - expected: vendor:product or busnum-devnum\n", device);

         g_clear_pointer(&self, g_free);

@@ -276,6 +280,20 @@ usbredir_log_cb(void *priv, int level, const char *msg)

     g_log_structured(G_LOG_DOMAIN, glog_level, "MESSAGE", msg);

 }

+static void

+update_watch(redirect *self)

+{

+    const bool watch_inout = usbredirhost_has_data_to_write(self->usbredirhost) != 0;

+    if (watch_inout == self->watch_inout) {

+        return;

+    }

+    g_source_remove(self->watch_server_id);

+    self->watch_server_id = 0;

+    self->watch_inout = watch_inout;

+

+    create_watch(self);

+}

+

 static int

 usbredir_read_cb(void *priv, uint8_t *data, int count)

 {

@@ -321,6 +339,7 @@ usbredir_write_cb(void *priv, uint8_t *data, int count)

         if (g_error_matches(err, G_IO_ERROR, G_IO_ERROR_WOULD_BLOCK)) {

             /* Try again later */

             nbytes = 0;

+            update_watch(self);

         } else {

             if (err != NULL) {

                 g_warning("Failure at %s: %s", __func__, err->message);

@@ -400,13 +419,18 @@ connection_handle_io_cb(GIOChannel *source, GIOCondition condition, gpointer use

             goto end;

         }

     }

-    if (condition & G_IO_OUT) {

+    // try to write data in any case, to avoid having another iteration and

+    // creation of another watch if there is space in output buffer

+    if (usbredirhost_has_data_to_write(self->usbredirhost) != 0) {

         int ret = usbredirhost_write_guest_data(self->usbredirhost);

         if (ret < 0) {

             g_critical("%s: Failed to write to guest", __func__);

             goto end;

         }

     }

+

+    // update the watch if needed

+    update_watch(self);

     return G_SOURCE_CONTINUE;

 end:

@@ -427,7 +451,7 @@ create_watch(redirect *self)

 #endif

     self->watch_server_id = g_io_add_watch(io_channel,

-            G_IO_IN | G_IO_OUT | G_IO_HUP | G_IO_ERR,

+            G_IO_IN | G_IO_HUP | G_IO_ERR | (self->watch_inout ? G_IO_OUT : 0),

             connection_handle_io_cb,

             self);

 }

-- 

2.39.0