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>From 9e799828d3a805184687792254c379ba4887ec60 Mon Sep 17 00:00:00 2001
From: Amit Shah <amit.shah@redhat.com>
Date: Mon, 21 Mar 2011 20:31:45 +0100
Subject: [PATCH 02/28] char: Add a QemuChrHandlers struct to initialise
 chardev handlers

Instead of passing each handler in the qemu_add_handlers() function,
create a struct of handlers that can be passed to the function instead.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 gdbstub.c               |    9 +++++++--
 hw/ccid-card-passthru.c |   11 +++++++----
 hw/debugcon.c           |    2 +-
 hw/escc.c               |    9 +++++++--
 hw/etraxfs_ser.c        |   13 +++++++++----
 hw/grlib_apbuart.c      |   12 +++++++-----
 hw/ivshmem.c            |   28 ++++++++++++++++++++++------
 hw/lm32_juart.c         |    8 +++++++-
 hw/lm32_uart.c          |    8 +++++++-
 hw/mcf_uart.c           |    9 +++++++--
 hw/milkymist-uart.c     |    8 +++++++-
 hw/pl011.c              |    9 +++++++--
 hw/pxa2xx.c             |   13 +++++++++----
 hw/serial.c             |    9 +++++++--
 hw/sh_serial.c          |   12 +++++++++---
 hw/spapr_vty.c          |    8 ++++++--
 hw/strongarm.c          |   12 +++++++-----
 hw/syborg_serial.c      |    9 +++++++--
 hw/usb-serial.c         |    9 +++++++--
 hw/virtio-console.c     |   11 ++++++++---
 hw/xen_console.c        |   16 +++++++++++-----
 hw/xilinx_uartlite.c    |   11 +++++++++--
 monitor.c               |   18 ++++++++++++++----
 net/slirp.c             |    8 ++++++--
 qemu-char.c             |   32 ++++++++++++++++++++++----------
 qemu-char.h             |   13 +++++++++----
 usb-redir.c             |    9 +++++++--
 27 files changed, 233 insertions(+), 83 deletions(-)

diff --git a/gdbstub.c b/gdbstub.c
index 27b0cfa..6639849 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -2739,6 +2739,12 @@ static void gdb_sigterm_handler(int signal)
 }
 #endif
 
+static const QemuChrHandlers gdb_handlers = {
+    .fd_can_read = gdb_chr_can_receive,
+    .fd_read = gdb_chr_receive,
+    .fd_event = gdb_chr_event,
+};
+
 int gdbserver_start(const char *device)
 {
     GDBState *s;
@@ -2768,8 +2774,7 @@ int gdbserver_start(const char *device)
         if (!chr)
             return -1;
 
-        qemu_chr_add_handlers(chr, gdb_chr_can_receive, gdb_chr_receive,
-                              gdb_chr_event, NULL);
+        qemu_chr_add_handlers(chr, &gdb_handlers, NULL);
     }
 
     s = gdbserver_state;
diff --git a/hw/ccid-card-passthru.c b/hw/ccid-card-passthru.c
index 28eb9d1..1dee6f7 100644
--- a/hw/ccid-card-passthru.c
+++ b/hw/ccid-card-passthru.c
@@ -273,6 +273,12 @@ static const uint8_t *passthru_get_atr(CCIDCardState *base, uint32_t *len)
     return card->atr;
 }
 
+static const QemuChrHandlers passthru_handlers = {
+    .fd_can_read = ccid_card_vscard_can_read,
+    .fd_read = ccid_card_vscard_read,
+    .fd_event = ccid_card_vscard_event,
+};
+
 static int passthru_initfn(CCIDCardState *base)
 {
     PassthruState *card = DO_UPCAST(PassthruState, base, base);
@@ -281,10 +287,7 @@ static int passthru_initfn(CCIDCardState *base)
     card->vscard_in_hdr = 0;
     if (card->cs) {
         DPRINTF(card, D_INFO, "initing chardev\n");
-        qemu_chr_add_handlers(card->cs,
-            ccid_card_vscard_can_read,
-            ccid_card_vscard_read,
-            ccid_card_vscard_event, card);
+        qemu_chr_add_handlers(card->cs, &passthru_handlers, card);
         ccid_card_vscard_send_init(card);
     } else {
         error_report("missing chardev");
diff --git a/hw/debugcon.c b/hw/debugcon.c
index 5ee6821..e79a595 100644
--- a/hw/debugcon.c
+++ b/hw/debugcon.c
@@ -73,7 +73,7 @@ static void debugcon_init_core(DebugconState *s)
         exit(1);
     }
 
-    qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, s);
+    qemu_chr_add_handlers(s->chr, NULL, s);
 }
 
 static int debugcon_isa_initfn(ISADevice *dev)
diff --git a/hw/escc.c b/hw/escc.c
index f6fd919..dfa329a 100644
--- a/hw/escc.c
+++ b/hw/escc.c
@@ -898,6 +898,12 @@ void slavio_serial_ms_kbd_init(target_phys_addr_t base, qemu_irq irq,
     sysbus_mmio_map(s, 0, base);
 }
 
+static const QemuChrHandlers serial_handlers = {
+    .fd_can_read = serial_can_receive,
+    .fd_read = serial_receive1,
+    .fd_event = serial_event,
+};
+
 static int escc_init1(SysBusDevice *dev)
 {
     SerialState *s = FROM_SYSBUS(SerialState, dev);
@@ -911,8 +917,7 @@ static int escc_init1(SysBusDevice *dev)
         s->chn[i].chn = 1 - i;
         s->chn[i].clock = s->frequency / 2;
         if (s->chn[i].chr) {
-            qemu_chr_add_handlers(s->chn[i].chr, serial_can_receive,
-                                  serial_receive1, serial_event, &s->chn[i]);
+            qemu_chr_add_handlers(s->chn[i].chr, &serial_handlers, &s->chn[i]);
         }
     }
     s->chn[0].otherchn = &s->chn[1];
diff --git a/hw/etraxfs_ser.c b/hw/etraxfs_ser.c
index b917d4d..ebbad77 100644
--- a/hw/etraxfs_ser.c
+++ b/hw/etraxfs_ser.c
@@ -202,6 +202,12 @@ static void etraxfs_ser_reset(DeviceState *d)
 
 }
 
+static const QemuChrHandlers serial_handlers = {
+    .fd_can_read = serial_can_receive,
+    .fd_read = serial_receive,
+    .fd_event = serial_event,
+};
+
 static int etraxfs_ser_init(SysBusDevice *dev)
 {
     struct etrax_serial *s = FROM_SYSBUS(typeof (*s), dev);
@@ -212,10 +218,9 @@ static int etraxfs_ser_init(SysBusDevice *dev)
                                       DEVICE_NATIVE_ENDIAN);
     sysbus_init_mmio(dev, R_MAX * 4, ser_regs);
     s->chr = qdev_init_chardev(&dev->qdev);
-    if (s->chr)
-        qemu_chr_add_handlers(s->chr,
-                      serial_can_receive, serial_receive,
-                      serial_event, s);
+    if (s->chr) {
+        qemu_chr_add_handlers(s->chr, &serial_handlers, s);
+    }
     return 0;
 }
 
diff --git a/hw/grlib_apbuart.c b/hw/grlib_apbuart.c
index 169a56e..310687b 100644
--- a/hw/grlib_apbuart.c
+++ b/hw/grlib_apbuart.c
@@ -144,16 +144,18 @@ static CPUWriteMemoryFunc * const grlib_apbuart_write[] = {
     NULL, NULL, grlib_apbuart_writel,
 };
 
+static const QemuChrHandlers grlib_handlers = {
+    .fd_can_read = grlib_apbuart_can_receive,
+    .fd_read = grlib_apbuart_receive,
+    .fd_event = grlib_apbuart_event,
+};
+
 static int grlib_apbuart_init(SysBusDevice *dev)
 {
     UART *uart      = FROM_SYSBUS(typeof(*uart), dev);
     int   uart_regs = 0;
 
-    qemu_chr_add_handlers(uart->chr,
-                          grlib_apbuart_can_receive,
-                          grlib_apbuart_receive,
-                          grlib_apbuart_event,
-                          uart);
+    qemu_chr_add_handlers(uart->chr, &grlib_handlers, uart);
 
     sysbus_init_irq(dev, &uart->irq);
 
diff --git a/hw/ivshmem.c b/hw/ivshmem.c
index 3055dd2..4f59575 100644
--- a/hw/ivshmem.c
+++ b/hw/ivshmem.c
@@ -312,6 +312,18 @@ static void fake_irqfd(void *opaque, const uint8_t *buf, int size) {
     msix_notify(pdev, entry->vector);
 }
 
+static const QemuChrHandlers ivshmem_handlers = {
+    .fd_can_read = ivshmem_can_receive,
+    .fd_read = ivshmem_receive,
+    .fd_event = ivshmem_event,
+};
+
+static const QemuChrHandlers ivshmem_msi_handlers = {
+    .fd_can_read = ivshmem_can_receive,
+    .fd_read = fake_irqfd,
+    .fd_event = ivshmem_event,
+};
+
 static CharDriverState* create_eventfd_chr_device(void * opaque, int eventfd,
                                                                     int vector)
 {
@@ -331,11 +343,10 @@ static CharDriverState* create_eventfd_chr_device(void * opaque, int eventfd,
         s->eventfd_table[vector].pdev = &s->dev;
         s->eventfd_table[vector].vector = vector;
 
-        qemu_chr_add_handlers(chr, ivshmem_can_receive, fake_irqfd,
-                      ivshmem_event, &s->eventfd_table[vector]);
+        qemu_chr_add_handlers(chr, &ivshmem_msi_handlers,
+                              &s->eventfd_table[vector]);
     } else {
-        qemu_chr_add_handlers(chr, ivshmem_can_receive, ivshmem_receive,
-                      ivshmem_event, s);
+        qemu_chr_add_handlers(chr, &ivshmem_handlers, s);
     }
 
     return chr;
@@ -666,6 +677,12 @@ static int ivshmem_load(QEMUFile* f, void *opaque, int version_id)
     return 0;
 }
 
+static const QemuChrHandlers ivshmem_server_handlers = {
+    .fd_can_read = ivshmem_can_receive,
+    .fd_read = ivshmem_read,
+    .fd_event = ivshmem_event,
+};
+
 static int pci_ivshmem_init(PCIDevice *dev)
 {
     IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
@@ -749,8 +766,7 @@ static int pci_ivshmem_init(PCIDevice *dev)
 
         s->eventfd_chr = qemu_mallocz(s->vectors * sizeof(CharDriverState *));
 
-        qemu_chr_add_handlers(s->server_chr, ivshmem_can_receive, ivshmem_read,
-                     ivshmem_event, s);
+        qemu_chr_add_handlers(s->server_chr, &ivshmem_server_handlers, s);
     } else {
         /* just map the file immediately, we're not using a server */
         int fd;
diff --git a/hw/lm32_juart.c b/hw/lm32_juart.c
index fddcf7e..12dd1e8 100644
--- a/hw/lm32_juart.c
+++ b/hw/lm32_juart.c
@@ -110,13 +110,19 @@ static void juart_reset(DeviceState *d)
     s->jrx = 0;
 }
 
+static const QemuChrHandlers juart_handlers = {
+    .fd_can_read = juart_can_rx,
+    .fd_read = juart_rx,
+    .fd_event = juart_event,
+};
+
 static int lm32_juart_init(SysBusDevice *dev)
 {
     LM32JuartState *s = FROM_SYSBUS(typeof(*s), dev);
 
     s->chr = qdev_init_chardev(&dev->qdev);
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, juart_can_rx, juart_rx, juart_event, s);
+        qemu_chr_add_handlers(s->chr, juart_handlers, s);
     }
 
     return 0;
diff --git a/hw/lm32_uart.c b/hw/lm32_uart.c
index 09090e9..5438660 100644
--- a/hw/lm32_uart.c
+++ b/hw/lm32_uart.c
@@ -242,6 +242,12 @@ static void uart_reset(DeviceState *d)
     s->regs[R_LSR] = LSR_THRE | LSR_TEMT;
 }
 
+static const QemuChrHandlers uart_handlers = {
+    .fd_can_read = uart_can_rx,
+    .fd_read = uart_rx,
+    .fd_event = uart_event,
+};
+
 static int lm32_uart_init(SysBusDevice *dev)
 {
     LM32UartState *s = FROM_SYSBUS(typeof(*s), dev);
@@ -255,7 +261,7 @@ static int lm32_uart_init(SysBusDevice *dev)
 
     s->chr = qdev_init_chardev(&dev->qdev);
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, uart_can_rx, uart_rx, uart_event, s);
+        qemu_chr_add_handlers(s->chr, uart_handlers, s);
     }
 
     return 0;
diff --git a/hw/mcf_uart.c b/hw/mcf_uart.c
index 905e116..bb5740c 100644
--- a/hw/mcf_uart.c
+++ b/hw/mcf_uart.c
@@ -268,6 +268,12 @@ static void mcf_uart_receive(void *opaque, const uint8_t *buf, int size)
     mcf_uart_push_byte(s, buf[0]);
 }
 
+static const QemuChrHandlers mcf_uart_handlers = {
+    .fd_can_read = mcf_uart_can_receive,
+    .fd_read = mcf_uart_receive,
+    .fd_event = mcf_uart_event,
+};
+
 void *mcf_uart_init(qemu_irq irq, CharDriverState *chr)
 {
     mcf_uart_state *s;
@@ -276,8 +282,7 @@ void *mcf_uart_init(qemu_irq irq, CharDriverState *chr)
     s->chr = chr;
     s->irq = irq;
     if (chr) {
-        qemu_chr_add_handlers(chr, mcf_uart_can_receive, mcf_uart_receive,
-                              mcf_uart_event, s);
+        qemu_chr_add_handlers(chr, &mcf_uart_handlers, s);
     }
     mcf_uart_reset(s);
     return s;
diff --git a/hw/milkymist-uart.c b/hw/milkymist-uart.c
index 56c90da..4412b1b 100644
--- a/hw/milkymist-uart.c
+++ b/hw/milkymist-uart.c
@@ -133,6 +133,12 @@ static void milkymist_uart_reset(DeviceState *d)
     }
 }
 
+static const QemuChrHandlers uart_handlers = {
+    .fd_can_read = uart_can_rx,
+    .fd_read = uart_rx,
+    .fd_event = uart_event,
+};
+
 static int milkymist_uart_init(SysBusDevice *dev)
 {
     MilkymistUartState *s = FROM_SYSBUS(typeof(*s), dev);
@@ -147,7 +153,7 @@ static int milkymist_uart_init(SysBusDevice *dev)
 
     s->chr = qdev_init_chardev(&dev->qdev);
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, uart_can_rx, uart_rx, uart_event, s);
+        qemu_chr_add_handlers(s->chr, uart_handlers, s);
     }
 
     return 0;
diff --git a/hw/pl011.c b/hw/pl011.c
index 997ce84..37ba7f6 100644
--- a/hw/pl011.c
+++ b/hw/pl011.c
@@ -260,6 +260,12 @@ static const VMStateDescription vmstate_pl011 = {
     }
 };
 
+static const QemuChrHandlers pl011_handlers = {
+    .fd_can_read = pl011_can_receive,
+    .fd_read = pl011_receive,
+    .fd_event = pl011_event,
+};
+
 static int pl011_init(SysBusDevice *dev, const unsigned char *id)
 {
     int iomemtype;
@@ -278,8 +284,7 @@ static int pl011_init(SysBusDevice *dev, const unsigned char *id)
     s->cr = 0x300;
     s->flags = 0x90;
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, pl011_can_receive, pl011_receive,
-                              pl011_event, s);
+        qemu_chr_add_handlers(s->chr, &pl011_handlers, s);
     }
     vmstate_register(&dev->qdev, -1, &vmstate_pl011, s);
     return 0;
diff --git a/hw/pxa2xx.c b/hw/pxa2xx.c
index cf93110..18bbe48 100644
--- a/hw/pxa2xx.c
+++ b/hw/pxa2xx.c
@@ -2019,6 +2019,12 @@ static int pxa2xx_fir_load(QEMUFile *f, void *opaque, int version_id)
     return 0;
 }
 
+static const QemuChrHandlers pxa2xx_handlers = {
+    .fd_can_read = pxa2xx_fir_is_empty,
+    .fd_read = pxa2xx_fir_rx,
+    .fd_event = pxa2xx_fir_event,
+};
+
 static PXA2xxFIrState *pxa2xx_fir_init(target_phys_addr_t base,
                 qemu_irq irq, qemu_irq rx_dma, qemu_irq tx_dma,
                 CharDriverState *chr)
@@ -2038,10 +2044,9 @@ static PXA2xxFIrState *pxa2xx_fir_init(target_phys_addr_t base,
                     pxa2xx_fir_writefn, s, DEVICE_NATIVE_ENDIAN);
     cpu_register_physical_memory(base, 0x1000, iomemtype);
 
-    if (chr)
-        qemu_chr_add_handlers(chr, pxa2xx_fir_is_empty,
-                        pxa2xx_fir_rx, pxa2xx_fir_event, s);
-
+    if (chr) {
+        qemu_chr_add_handlers(chr, &pxa2xx_handlers, s);
+    }
     register_savevm(NULL, "pxa2xx_fir", 0, 0, pxa2xx_fir_save,
                     pxa2xx_fir_load, s);
 
diff --git a/hw/serial.c b/hw/serial.c
index 0ee61dd..d496bcf 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -727,6 +727,12 @@ static void serial_reset(void *opaque)
     qemu_irq_lower(s->irq);
 }
 
+static const QemuChrHandlers serial_handlers = {
+    .fd_can_read = serial_can_receive1,
+    .fd_read = serial_receive1,
+    .fd_event = serial_event,
+};
+
 static void serial_init_core(SerialState *s)
 {
     if (!s->chr) {
@@ -741,8 +747,7 @@ static void serial_init_core(SerialState *s)
 
     qemu_register_reset(serial_reset, s);
 
-    qemu_chr_add_handlers(s->chr, serial_can_receive1, serial_receive1,
-                          serial_event, s);
+    qemu_chr_add_handlers(s->chr, &serial_handlers, s);
 }
 
 /* Change the main reference oscillator frequency. */
diff --git a/hw/sh_serial.c b/hw/sh_serial.c
index 191f4a6..8b6460d 100644
--- a/hw/sh_serial.c
+++ b/hw/sh_serial.c
@@ -350,6 +350,12 @@ static CPUWriteMemoryFunc * const sh_serial_writefn[] = {
     &sh_serial_write,
 };
 
+static const QemuChrHandlers sh_serial_handlers = {
+    .fd_can_read = sh_serial_can_receive1,
+    .fd_read = sh_serial_receive1,
+    .fd_event = sh_serial_event,
+};
+
 void sh_serial_init (target_phys_addr_t base, int feat,
 		     uint32_t freq, CharDriverState *chr,
 		     qemu_irq eri_source,
@@ -389,9 +395,9 @@ void sh_serial_init (target_phys_addr_t base, int feat,
 
     s->chr = chr;
 
-    if (chr)
-        qemu_chr_add_handlers(chr, sh_serial_can_receive1, sh_serial_receive1,
-			      sh_serial_event, s);
+    if (chr) {
+        qemu_chr_add_handlers(chr, &sh_serial_handlers, s);
+    }
 
     s->eri = eri_source;
     s->rxi = rxi_source;
diff --git a/hw/spapr_vty.c b/hw/spapr_vty.c
index 6fc0105..5968d85 100644
--- a/hw/spapr_vty.c
+++ b/hw/spapr_vty.c
@@ -54,12 +54,16 @@ void vty_putchars(VIOsPAPRDevice *sdev, uint8_t *buf, int len)
     qemu_chr_write(dev->chardev, buf, len);
 }
 
+static const QemuChrHandlers vty_handlers = {
+    .fd_can_read = vty_can_receive,
+    .fd_read = vty_receive,
+};
+
 static int spapr_vty_init(VIOsPAPRDevice *sdev)
 {
     VIOsPAPRVTYDevice *dev = (VIOsPAPRVTYDevice *)sdev;
 
-    qemu_chr_add_handlers(dev->chardev, vty_can_receive,
-                          vty_receive, NULL, dev);
+    qemu_chr_add_handlers(dev->chardev, vty_handlers, dev);
 
     return 0;
 }
diff --git a/hw/strongarm.c b/hw/strongarm.c
index 0e03d61..c2dce95 100644
--- a/hw/strongarm.c
+++ b/hw/strongarm.c
@@ -1188,6 +1188,12 @@ static CPUWriteMemoryFunc * const strongarm_uart_writefn[] = {
     strongarm_uart_write,
 };
 
+static const QemuChrHandlers strongarm_uart_handlers = {
+    .fd_can_read = strongarm_uart_can_receive,
+    .fd_read = strongarm_uart_receive,
+    .fd_event = strongarm_uart_event,
+};
+
 static int strongarm_uart_init(SysBusDevice *dev)
 {
     StrongARMUARTState *s = FROM_SYSBUS(StrongARMUARTState, dev);
@@ -1202,11 +1208,7 @@ static int strongarm_uart_init(SysBusDevice *dev)
     s->tx_timer = qemu_new_timer_ns(vm_clock, strongarm_uart_tx, s);
 
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr,
-                        strongarm_uart_can_receive,
-                        strongarm_uart_receive,
-                        strongarm_uart_event,
-                        s);
+        qemu_chr_add_handlers(s->chr, &strongarm_uart_handlers, s);
     }
 
     return 0;
diff --git a/hw/syborg_serial.c b/hw/syborg_serial.c
index 2ef7175..ac68022 100644
--- a/hw/syborg_serial.c
+++ b/hw/syborg_serial.c
@@ -292,6 +292,12 @@ static const VMStateDescription vmstate_syborg_serial = {
     }
 };
 
+static const QemuChrHandlers syborg_serial_handlers = {
+    .fd_can_read = syborg_serial_can_receive,
+    .fd_read = syborg_serial_receive,
+    .fd_event = syborg_serial_event,
+};
+
 static int syborg_serial_init(SysBusDevice *dev)
 {
     SyborgSerialState *s = FROM_SYSBUS(SyborgSerialState, dev);
@@ -304,8 +310,7 @@ static int syborg_serial_init(SysBusDevice *dev)
     sysbus_init_mmio(dev, 0x1000, iomemtype);
     s->chr = qdev_init_chardev(&dev->qdev);
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, syborg_serial_can_receive,
-                              syborg_serial_receive, syborg_serial_event, s);
+        qemu_chr_add_handlers(s->chr, &syborg_serial_handlers, s);
     }
     if (s->fifo_size <= 0) {
         fprintf(stderr, "syborg_serial: fifo too small\n");
diff --git a/hw/usb-serial.c b/hw/usb-serial.c
index c69c437..45d48ee 100644
--- a/hw/usb-serial.c
+++ b/hw/usb-serial.c
@@ -476,6 +476,12 @@ static void usb_serial_event(void *opaque, int event)
     }
 }
 
+static const QemuChrHandlers usb_serial_handlers = {
+    .fd_can_read = usb_serial_can_read,
+    .fd_read = usb_serial_read,
+    .fd_event = usb_serial_event,
+};
+
 static int usb_serial_initfn(USBDevice *dev)
 {
     USBSerialState *s = DO_UPCAST(USBSerialState, dev, dev);
@@ -487,8 +493,7 @@ static int usb_serial_initfn(USBDevice *dev)
         return -1;
     }
 
-    qemu_chr_add_handlers(s->cs, usb_serial_can_read, usb_serial_read,
-                          usb_serial_event, s);
+    qemu_chr_add_handlers(s->cs, &usb_serial_handlers, s);
     usb_serial_handle_reset(dev);
     return 0;
 }
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index fe5e188..cfc3087 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -95,6 +95,12 @@ static void chr_event(void *opaque, int event)
     }
 }
 
+static const QemuChrHandlers chr_handlers = {
+    .fd_can_read = chr_can_read,
+    .fd_read = chr_read,
+    .fd_event = chr_event,
+};
+
 static int virtconsole_initfn(VirtIOSerialPort *port)
 {
     VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
@@ -107,8 +113,7 @@ static int virtconsole_initfn(VirtIOSerialPort *port)
     }
 
     if (vcon->chr) {
-        qemu_chr_add_handlers(vcon->chr, chr_can_read, chr_read, chr_event,
-                              vcon);
+        qemu_chr_add_handlers(vcon->chr, &chr_handlers, vcon);
         info->have_data = flush_buf;
         info->guest_open = guest_open;
         info->guest_close = guest_close;
@@ -126,7 +131,7 @@ static int virtconsole_exitfn(VirtIOSerialPort *port)
 	 * Instead of closing the chardev, free it so it can be used
 	 * for other purposes.
 	 */
-	qemu_chr_add_handlers(vcon->chr, NULL, NULL, NULL, NULL);
+	qemu_chr_add_handlers(vcon->chr, NULL, NULL);
     }
 
     return 0;
diff --git a/hw/xen_console.c b/hw/xen_console.c
index 8ef104c..85e8a22 100644
--- a/hw/xen_console.c
+++ b/hw/xen_console.c
@@ -212,6 +212,11 @@ out:
     return ret;
 }
 
+static const QemuChrHandlers xencons_handlers = {
+    .fd_can_read = xencons_can_receive,
+    .fd_read = xencons_receive,
+};
+
 static int con_connect(struct XenDevice *xendev)
 {
     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
@@ -232,9 +237,9 @@ static int con_connect(struct XenDevice *xendev)
 	return -1;
 
     xen_be_bind_evtchn(&con->xendev);
-    if (con->chr)
-        qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
-                              NULL, con);
+    if (con->chr) {
+        qemu_chr_add_handlers(con->chr, &xencons_handlers, con);
+    }
 
     xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 		  con->ring_ref,
@@ -248,8 +253,9 @@ static void con_disconnect(struct XenDevice *xendev)
 {
     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 
-    if (con->chr)
-        qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
+    if (con->chr) {
+        qemu_chr_add_handlers(con->chr, NULL, NULL);
+    }
     xen_be_unbind_evtchn(&con->xendev);
 
     if (con->sring) {
diff --git a/hw/xilinx_uartlite.c b/hw/xilinx_uartlite.c
index 9b94e98..1845577 100644
--- a/hw/xilinx_uartlite.c
+++ b/hw/xilinx_uartlite.c
@@ -193,6 +193,12 @@ static void uart_event(void *opaque, int event)
 
 }
 
+static const QemuChrHandlers uart_handlers = {
+    .fd_can_read = uart_can_rx,
+    .fd_read = uart_rx,
+    .fd_event = uart_event,
+};
+
 static int xilinx_uartlite_init(SysBusDevice *dev)
 {
     struct xlx_uartlite *s = FROM_SYSBUS(typeof (*s), dev);
@@ -206,8 +212,9 @@ static int xilinx_uartlite_init(SysBusDevice *dev)
     sysbus_init_mmio(dev, R_MAX * 4, uart_regs);
 
     s->chr = qdev_init_chardev(&dev->qdev);
-    if (s->chr)
-        qemu_chr_add_handlers(s->chr, uart_can_rx, uart_rx, uart_event, s);
+    if (s->chr) {
+        qemu_chr_add_handlers(s->chr, &uart_handlers, s);
+    }
     return 0;
 }
 
diff --git a/monitor.c b/monitor.c
index 718935b..5b79dde 100644
--- a/monitor.c
+++ b/monitor.c
@@ -5249,6 +5249,18 @@ static void monitor_event(void *opaque, int event)
  * End:
  */
 
+static const QemuChrHandlers monitor_handlers = {
+    .fd_can_read = monitor_can_read,
+    .fd_read = monitor_read,
+    .fd_event = monitor_event,
+};
+
+static const QemuChrHandlers monitor_control_handlers = {
+    .fd_can_read = monitor_can_read,
+    .fd_read = monitor_control_read,
+    .fd_event = monitor_control_event,
+};
+
 void monitor_init(CharDriverState *chr, int flags)
 {
     static int is_first_init = 1;
@@ -5271,12 +5283,10 @@ void monitor_init(CharDriverState *chr, int flags)
     if (monitor_ctrl_mode(mon)) {
         mon->mc = qemu_mallocz(sizeof(MonitorControl));
         /* Control mode requires special handlers */
-        qemu_chr_add_handlers(chr, monitor_can_read, monitor_control_read,
-                              monitor_control_event, mon);
+        qemu_chr_add_handlers(chr, &monitor_control_handlers, mon);
         qemu_chr_set_echo(chr, true);
     } else {
-        qemu_chr_add_handlers(chr, monitor_can_read, monitor_read,
-                              monitor_event, mon);
+        qemu_chr_add_handlers(chr, &monitor_handlers, mon);
     }
 
     QLIST_INSERT_HEAD(&mon_list, mon, entry);
diff --git a/net/slirp.c b/net/slirp.c
index 157b80a..8eeec7e 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -577,6 +577,11 @@ static void guestfwd_read(void *opaque, const uint8_t *buf, int size)
     slirp_socket_recv(fwd->slirp, fwd->server, fwd->port, buf, size);
 }
 
+static const QemuChrHandlers guestfwd_handlers = {
+    .fd_can_read = guestfwd_can_read,
+    .fd_read = guestfwd_read,
+};
+
 static int slirp_guestfwd(SlirpState *s, const char *config_str,
                           int legacy_format)
 {
@@ -633,8 +638,7 @@ static int slirp_guestfwd(SlirpState *s, const char *config_str,
     fwd->port = port;
     fwd->slirp = s->slirp;
 
-    qemu_chr_add_handlers(fwd->hd, guestfwd_can_read, guestfwd_read,
-                          NULL, fwd);
+    qemu_chr_add_handlers(fwd->hd, &guestfwd_handlers, fwd);
     return 0;
 
  fail_syntax:
diff --git a/qemu-char.c b/qemu-char.c
index 5682aea..52bcc0e 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -195,19 +195,26 @@ void qemu_chr_send_event(CharDriverState *s, int event)
         s->chr_send_event(s, event);
 }
 
+static const QemuChrHandlers null_handlers = {
+    /* All handlers are initialised to NULL */
+};
+
 void qemu_chr_add_handlers(CharDriverState *s,
-                           IOCanReadHandler *fd_can_read,
-                           IOReadHandler *fd_read,
-                           IOEventHandler *fd_event,
-                           void *opaque)
+                           const QemuChrHandlers *handlers, void *opaque)
 {
-    if (!opaque && !fd_can_read && !fd_read && !fd_event) {
+    if (!s) {
+        return;
+    }
+    if (!opaque && !handlers) {
         /* chr driver being released. */
         ++s->avail_connections;
     }
-    s->chr_can_read = fd_can_read;
-    s->chr_read = fd_read;
-    s->chr_event = fd_event;
+    if (!handlers) {
+        handlers = &null_handlers;
+    }
+    s->chr_can_read = handlers->fd_can_read;
+    s->chr_read = handlers->fd_read;
+    s->chr_event = handlers->fd_event;
     s->handler_opaque = opaque;
     if (s->chr_update_read_handler)
         s->chr_update_read_handler(s);
@@ -447,6 +454,12 @@ static void mux_chr_event(void *opaque, int event)
         mux_chr_send_event(d, i, event);
 }
 
+static const QemuChrHandlers mux_chr_handlers = {
+    .fd_can_read = mux_chr_can_read,
+    .fd_read = mux_chr_read,
+    .fd_event = mux_chr_event,
+};
+
 static void mux_chr_update_read_handler(CharDriverState *chr)
 {
     MuxDriver *d = chr->opaque;
@@ -461,8 +474,7 @@ static void mux_chr_update_read_handler(CharDriverState *chr)
     d->chr_event[d->mux_cnt] = chr->chr_event;
     /* Fix up the real driver with mux routines */
     if (d->mux_cnt == 0) {
-        qemu_chr_add_handlers(d->drv, mux_chr_can_read, mux_chr_read,
-                              mux_chr_event, chr);
+        qemu_chr_add_handlers(d->drv, &mux_chr_handlers, chr);
     }
     if (d->focus != -1) {
         mux_chr_send_event(d, d->focus, CHR_EVENT_MUX_OUT);
diff --git a/qemu-char.h b/qemu-char.h
index f361c6d..b8372ea 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -1,6 +1,7 @@
 #ifndef QEMU_CHAR_H
 #define QEMU_CHAR_H
 
+#include <stdbool.h>
 #include "qemu-common.h"
 #include "qemu-queue.h"
 #include "qemu-option.h"
@@ -77,6 +78,13 @@ struct CharDriverState {
     QTAILQ_ENTRY(CharDriverState) next;
 };
 
+typedef struct QemuChrHandlers {
+    IOCanReadHandler *fd_can_read;
+    IOReadHandler *fd_read;
+    IOHandler *fd_write_unblocked;
+    IOEventHandler *fd_event;
+} QemuChrHandlers;
+
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename);
 CharDriverState *qemu_chr_open_opts(QemuOpts *opts,
                                     void (*init)(struct CharDriverState *s));
@@ -89,10 +97,7 @@ void qemu_chr_printf(CharDriverState *s, const char *fmt, ...)
     GCC_FMT_ATTR(2, 3);
 int qemu_chr_write(CharDriverState *s, const uint8_t *buf, int len);
 void qemu_chr_send_event(CharDriverState *s, int event);
-void qemu_chr_add_handlers(CharDriverState *s,
-                           IOCanReadHandler *fd_can_read,
-                           IOReadHandler *fd_read,
-                           IOEventHandler *fd_event,
+void qemu_chr_add_handlers(CharDriverState *s, const QemuChrHandlers *handlers,
                            void *opaque);
 int qemu_chr_ioctl(CharDriverState *s, int cmd, void *arg);
 void qemu_chr_generic_open(CharDriverState *s);
diff --git a/usb-redir.c b/usb-redir.c
index e212993..e2b5a2c 100644
--- a/usb-redir.c
+++ b/usb-redir.c
@@ -782,6 +782,12 @@ static void usbredir_chardev_event(void *opaque, int event)
     }
 }
 
+static const QemuChrHandlers usbredir_chr_handlers = {
+    .fd_can_read = usbredir_chardev_can_read,
+    .fd_read = usbredir_chardev_read,
+    .fd_event = usbredir_chardev_event,
+};
+
 /*
  * init + destroy
  */
@@ -807,8 +813,7 @@ static int usbredir_initfn(USBDevice *udev)
     /* We'll do the attach once we receive the speed from the usb-host */
     udev->auto_attach = 0;
 
-    qemu_chr_add_handlers(dev->cs, usbredir_chardev_can_read,
-                          usbredir_chardev_read, usbredir_chardev_event, dev);
+    qemu_chr_add_handlers(dev->cs, &usbredir_chr_handlers, dev);
 
     return 0;
 }
-- 
1.7.5.1