qxl: replace pipe signaling with bottom half

qxl creates a pipe, then writes something to it to wake up the iothread
from the spice server thread to raise an irq.  These days qemu bottom
halves can be scheduled from threads and signals, so there is no reason
to do this any more.  Time to clean it up.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/display/qxl.c

@@ -1701,15 +1701,9 @@ static const MemoryRegionOps qxl_io_ops = {
     },
 };
 
-static void pipe_read(void *opaque)
+static void qxl_update_irq_bh(void *opaque)
 {
     PCIQXLDevice *d = opaque;
-    char dummy;
-    int len;
-
-    do {
-        len = read(d->pipe[0], &dummy, sizeof(dummy));
-    } while (len == sizeof(dummy));
     qxl_update_irq(d);
 }
 
@@ -1730,28 +1724,7 @@ static void qxl_send_events(PCIQXLDevice *d, uint32_t events)
     if ((old_pending & le_events) == le_events) {
         return;
     }
-    if (qemu_thread_is_self(&d->main)) {
-        qxl_update_irq(d);
-    } else {
-        if (write(d->pipe[1], d, 1) != 1) {
-            dprint(d, 1, "%s: write to pipe failed\n", __func__);
-        }
-    }
-}
-
-static void init_pipe_signaling(PCIQXLDevice *d)
-{
-    if (pipe(d->pipe) < 0) {
-        fprintf(stderr, "%s:%s: qxl pipe creation failed\n",
-                __FILE__, __func__);
-        exit(1);
-    }
-    fcntl(d->pipe[0], F_SETFL, O_NONBLOCK);
-    fcntl(d->pipe[1], F_SETFL, O_NONBLOCK);
-    fcntl(d->pipe[0], F_SETOWN, getpid());
-
-    qemu_thread_get_self(&d->main);
-    qemu_set_fd_handler(d->pipe[0], pipe_read, NULL, d);
+    qemu_bh_schedule(d->update_irq);
 }
 
 /* graphics console */
@@ -2044,7 +2017,7 @@ static int qxl_init_common(PCIQXLDevice *qxl)
     }
     qemu_add_vm_change_state_handler(qxl_vm_change_state_handler, qxl);
 
-    init_pipe_signaling(qxl);
+    qxl->update_irq = qemu_bh_new(qxl_update_irq_bh, qxl);
     qxl_reset_state(qxl);
 
     qxl->update_area_bh = qemu_bh_new(qxl_render_update_area_bh, qxl);

hw/display/qxl.h

@@ -81,8 +81,7 @@ typedef struct PCIQXLDevice {
     QemuMutex          track_lock;
 
     /* thread signaling */
-    QemuThread         main;
-    int                pipe[2];
+    QEMUBH             *update_irq;
 
     /* ram pci bar */
     QXLRam             *ram;