qemu/0002-char-Add-a-QemuChrHandlers-struct-to-initialise-char.patch

From 260acf7f716aa138138dc301b80a1bd10761b0bc 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] 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>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
---
 backends/rng-egd.c          | 12 +++++++++---
 gdbstub.c                   |  9 +++++++--
 hw/cadence_uart.c           |  9 +++++++--
 hw/ccid-card-passthru.c     | 11 +++++++----
 hw/debugcon.c               |  2 +-
 hw/escc.c                   |  9 +++++++--
 hw/etraxfs_ser.c            | 13 +++++++++----
 hw/exynos4210_uart.c        |  9 +++++++--
 hw/grlib_apbuart.c          | 12 +++++++-----
 hw/imx_serial.c             |  9 +++++++--
 hw/ipoctal232.c             |  9 +++++++--
 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/qdev-properties-system.c |  2 +-
 hw/s390x/sclpconsole.c      |  9 +++++++--
 hw/serial.c                 | 11 ++++++++---
 hw/sh_serial.c              | 12 +++++++++---
 hw/spapr_vty.c              |  8 ++++++--
 hw/strongarm.c              | 12 +++++++-----
 hw/usb/dev-serial.c         | 11 ++++++++---
 hw/usb/redirect.c           |  9 +++++++--
 hw/virtio-console.c         |  9 +++++++--
 hw/xen_console.c            | 16 +++++++++++-----
 hw/xilinx_uartlite.c        | 11 +++++++++--
 include/char/char.h         | 13 +++++++++----
 monitor.c                   | 18 ++++++++++++++----
 net/slirp.c                 |  8 ++++++--
 qemu-char.c                 | 32 ++++++++++++++++++++++----------
 qtest.c                     |  9 ++++++++-
 34 files changed, 280 insertions(+), 97 deletions(-)

diff --git a/backends/rng-egd.c b/backends/rng-egd.c
index 5e012e9..b09876a 100644
--- a/backends/rng-egd.c
+++ b/backends/rng-egd.c
@@ -133,6 +133,13 @@ static void rng_egd_cancel_requests(RngBackend *b)
     rng_egd_free_requests(s);
 }
 
+static const QemuChrHandlers rng_egd_handlers = {
+    .fd_can_read = rng_egd_chr_can_read,
+    .fd_read = rng_egd_chr_read,
+    .fd_event = NULL,
+};
+
+
 static void rng_egd_opened(RngBackend *b, Error **errp)
 {
     RngEgd *s = RNG_EGD(b);
@@ -150,8 +157,7 @@ static void rng_egd_opened(RngBackend *b, Error **errp)
     }
 
     /* FIXME we should resubmit pending requests when the CDS reconnects. */
-    qemu_chr_add_handlers(s->chr, rng_egd_chr_can_read, rng_egd_chr_read,
-                          NULL, s);
+    qemu_chr_add_handlers(s->chr, &rng_egd_handlers, s);
 }
 
 static void rng_egd_set_chardev(Object *obj, const char *value, Error **errp)
@@ -190,7 +196,7 @@ static void rng_egd_finalize(Object *obj)
     RngEgd *s = RNG_EGD(obj);
 
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL);
+        qemu_chr_add_handlers(s->chr, NULL, NULL);
     }
 
     g_free(s->chr_name);
diff --git a/gdbstub.c b/gdbstub.c
index 6cd26f1..2da07e9 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -2992,6 +2992,12 @@ 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;
@@ -3021,8 +3027,7 @@ 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/cadence_uart.c b/hw/cadence_uart.c
index 5766d38..dd1a7d6 100644
--- a/hw/cadence_uart.c
+++ b/hw/cadence_uart.c
@@ -439,6 +439,12 @@ static void cadence_uart_reset(UartState *s)
     s->rx_wpos = 0;
 }
 
+static const QemuChrHandlers cadence_uart_handlers = {
+    .fd_can_read = uart_can_receive,
+    .fd_read = uart_receive,
+    .fd_event = uart_event,
+};
+
 static int cadence_uart_init(SysBusDevice *dev)
 {
     UartState *s = FROM_SYSBUS(UartState, dev);
@@ -460,8 +466,7 @@ static int cadence_uart_init(SysBusDevice *dev)
     cadence_uart_reset(s);
 
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, uart_can_receive, uart_receive,
-                              uart_event, s);
+        qemu_chr_add_handlers(s->chr, &cadence_uart_handlers, s);
     }
 
     return 0;
diff --git a/hw/ccid-card-passthru.c b/hw/ccid-card-passthru.c
index 984bd0b..0dde761 100644
--- a/hw/ccid-card-passthru.c
+++ b/hw/ccid-card-passthru.c
@@ -274,6 +274,12 @@ 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);
@@ -282,10 +288,7 @@ 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 81b2bb0..58e1f90 100644
--- a/hw/debugcon.c
+++ b/hw/debugcon.c
@@ -88,7 +88,7 @@ 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 18c0292..a29784a 100644
--- a/hw/escc.c
+++ b/hw/escc.c
@@ -867,6 +867,12 @@ void slavio_serial_ms_kbd_init(hwaddr 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);
@@ -879,8 +885,7 @@ 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 72c8868..eb93166 100644
--- a/hw/etraxfs_ser.c
+++ b/hw/etraxfs_ser.c
@@ -208,6 +208,12 @@ 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);
@@ -217,10 +223,9 @@ static int etraxfs_ser_init(SysBusDevice *dev)
     sysbus_init_mmio(dev, &s->mmio);
 
     s->chr = qemu_char_get_next_serial();
-    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/exynos4210_uart.c b/hw/exynos4210_uart.c
index bdf797a..8419deb 100644
--- a/hw/exynos4210_uart.c
+++ b/hw/exynos4210_uart.c
@@ -625,6 +625,12 @@ DeviceState *exynos4210_uart_create(hwaddr addr,
     return dev;
 }
 
+static const QemuChrHandlers exynos4210_handlers = {
+    .fd_can_read = exynos4210_uart_can_receive,
+    .fd_read     = exynos4210_uart_receive,
+    .fd_event    = exynos4210_uart_event,
+};
+
 static int exynos4210_uart_init(SysBusDevice *dev)
 {
     Exynos4210UartState *s = FROM_SYSBUS(Exynos4210UartState, dev);
@@ -636,8 +642,7 @@ static int exynos4210_uart_init(SysBusDevice *dev)
 
     sysbus_init_irq(dev, &s->irq);
 
-    qemu_chr_add_handlers(s->chr, exynos4210_uart_can_receive,
-                          exynos4210_uart_receive, exynos4210_uart_event, s);
+    qemu_chr_add_handlers(s->chr, &exynos4210_handlers, s);
 
     return 0;
 }
diff --git a/hw/grlib_apbuart.c b/hw/grlib_apbuart.c
index 760bed0..7ede2be 100644
--- a/hw/grlib_apbuart.c
+++ b/hw/grlib_apbuart.c
@@ -222,15 +222,17 @@ static const MemoryRegionOps grlib_apbuart_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
+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);
 
-    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/imx_serial.c b/hw/imx_serial.c
index 2d8253e..b0401a1 100644
--- a/hw/imx_serial.c
+++ b/hw/imx_serial.c
@@ -381,6 +381,12 @@ static const struct MemoryRegionOps imx_serial_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
+static const QemuChrHandlers imx_handlers = {
+    .fd_can_read = imx_can_receive,
+    .fd_read = imx_receive,
+    .fd_event = imx_event,
+};
+
 static int imx_serial_init(SysBusDevice *dev)
 {
     IMXSerialState *s = FROM_SYSBUS(IMXSerialState, dev);
@@ -391,8 +397,7 @@ static int imx_serial_init(SysBusDevice *dev)
     sysbus_init_irq(dev, &s->irq);
 
     if (s->chr) {
-        qemu_chr_add_handlers(s->chr, imx_can_receive, imx_receive,
-                              imx_event, s);
+        qemu_chr_add_handlers(s->chr, &imx_handlers, s);
     } else {
         DPRINTF("No char dev for uart at 0x%lx\n",
                 (unsigned long)s->iomem.ram_addr);
diff --git a/hw/ipoctal232.c b/hw/ipoctal232.c
index c1e3b19..9d1eacf 100644
--- a/hw/ipoctal232.c
+++ b/hw/ipoctal232.c
@@ -535,6 +535,12 @@ static void hostdev_event(void *opaque, int event)
     }
 }
 
+static const QemuChrHandlers ipoctal_chr_handlers = {
+    .fd_can_read = hostdev_can_receive,
+    .fd_read = hostdev_receive,
+    .fd_event = hostdev_event,
+};
+
 static int ipoctal_init(IPackDevice *ip)
 {
     IPOctalState *s = IPOCTAL(ip);
@@ -556,8 +562,7 @@ static int ipoctal_init(IPackDevice *ip)
 
             if (ch->dev) {
                 index++;
-                qemu_chr_add_handlers(ch->dev, hostdev_can_receive,
-                                      hostdev_receive, hostdev_event, ch);
+                qemu_chr_add_handlers(ch->dev, &ipoctal_chr_handlers, ch);
                 DPRINTF("Redirecting channel %u to %s (%s)\n",
                         i, ch->devpath, label);
             } else {
diff --git a/hw/ivshmem.c b/hw/ivshmem.c
index afaf9b3..7577307 100644
--- a/hw/ivshmem.c
+++ b/hw/ivshmem.c
@@ -278,6 +278,18 @@ 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, EventNotifier *n,
                                                   int vector)
 {
@@ -298,11 +310,10 @@ static CharDriverState* create_eventfd_chr_device(void * opaque, EventNotifier *
         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;
@@ -636,6 +647,12 @@ static void ivshmem_write_config(PCIDevice *pci_dev, uint32_t address,
     msix_write_config(pci_dev, address, val, len);
 }
 
+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);
@@ -726,8 +743,7 @@ static int pci_ivshmem_init(PCIDevice *dev)
 
         s->eventfd_chr = g_malloc0(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 8c82c85..840f588 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 = qemu_char_get_next_serial();
     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 9c89cca..19cfd01 100644
--- a/hw/lm32_uart.c
+++ b/hw/lm32_uart.c
@@ -243,6 +243,12 @@ 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);
@@ -254,7 +260,7 @@ static int lm32_uart_init(SysBusDevice *dev)
 
     s->chr = qemu_char_get_next_serial();
     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 c443443..fc491f1 100644
--- a/hw/mcf_uart.c
+++ b/hw/mcf_uart.c
@@ -272,6 +272,12 @@ 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;
@@ -280,8 +286,7 @@ 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 e73eb84..3e03c5c 100644
--- a/hw/milkymist-uart.c
+++ b/hw/milkymist-uart.c
@@ -189,6 +189,12 @@ static void milkymist_uart_reset(DeviceState *d)
     s->regs[R_STAT] = STAT_THRE;
 }
 
+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);
@@ -201,7 +207,7 @@ static int milkymist_uart_init(SysBusDevice *dev)
 
     s->chr = qemu_char_get_next_serial();
     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 002a50e..3224bc9 100644
--- a/hw/pl011.c
+++ b/hw/pl011.c
@@ -261,6 +261,12 @@ 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)
 {
     pl011_state *s = FROM_SYSBUS(pl011_state, dev);
@@ -276,8 +282,7 @@ 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 d303320..06f43d5 100644
--- a/hw/pxa2xx.c
+++ b/hw/pxa2xx.c
@@ -1962,6 +1962,12 @@ 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(MemoryRegion *sysmem,
                 hwaddr base,
                 qemu_irq irq, qemu_irq rx_dma, qemu_irq tx_dma,
@@ -1980,10 +1986,9 @@ static PXA2xxFIrState *pxa2xx_fir_init(MemoryRegion *sysmem,
     memory_region_init_io(&s->iomem, &pxa2xx_fir_ops, s, "pxa2xx-fir", 0x1000);
     memory_region_add_subregion(sysmem, base, &s->iomem);
 
-    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/qdev-properties-system.c b/hw/qdev-properties-system.c
index ce3af22..dd37f58 100644
--- a/hw/qdev-properties-system.c
+++ b/hw/qdev-properties-system.c
@@ -138,7 +138,7 @@ static void release_chr(Object *obj, const char *name, void *opaque)
     CharDriverState **ptr = qdev_get_prop_ptr(dev, prop);
 
     if (*ptr) {
-        qemu_chr_add_handlers(*ptr, NULL, NULL, NULL, NULL);
+        qemu_chr_add_handlers(*ptr, NULL, NULL);
     }
 }
 
diff --git a/hw/s390x/sclpconsole.c b/hw/s390x/sclpconsole.c
index effe511..7a77d64 100644
--- a/hw/s390x/sclpconsole.c
+++ b/hw/s390x/sclpconsole.c
@@ -238,6 +238,12 @@ static void trigger_ascii_console_data(void *env, int n, int level)
     sclp_service_interrupt(0);
 }
 
+static const QemuChrHandlers sclp_chr_handlers = {
+    .fd_can_read = chr_can_read,
+    .fd_read = chr_read,
+    .fd_event = chr_event,
+};
+
 /* qemu object creation and initialization functions */
 
 /* tell character layer our call-back functions */
@@ -254,8 +260,7 @@ static int console_init(SCLPEvent *event)
     console_available = true;
     event->event_type = SCLP_EVENT_ASCII_CONSOLE_DATA;
     if (scon->chr) {
-        qemu_chr_add_handlers(scon->chr, chr_can_read,
-                              chr_read, chr_event, scon);
+        qemu_chr_add_handlers(scon->chr, &sclp_chr_handlers, scon);
     }
     scon->irq_read_vt220 = *qemu_allocate_irqs(trigger_ascii_console_data,
                                                NULL, 1);
diff --git a/hw/serial.c b/hw/serial.c
index f0ce9b0..589c18a 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -674,6 +674,12 @@ 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,
+};
+
 void serial_init_core(SerialState *s)
 {
     if (!s->chr) {
@@ -688,13 +694,12 @@ 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);
 }
 
 void serial_exit_core(SerialState *s)
 {
-    qemu_chr_add_handlers(s->chr, NULL, NULL, NULL, NULL);
+    qemu_chr_add_handlers(s->chr, NULL, NULL);
     qemu_unregister_reset(serial_reset, s);
 }
 
diff --git a/hw/sh_serial.c b/hw/sh_serial.c
index 21c5b13..1cae7e9 100644
--- a/hw/sh_serial.c
+++ b/hw/sh_serial.c
@@ -352,6 +352,12 @@ static const MemoryRegionOps sh_serial_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
+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(MemoryRegion *sysmem,
                     hwaddr base, int feat,
                     uint32_t freq, CharDriverState *chr,
@@ -396,9 +402,9 @@ void sh_serial_init(MemoryRegion *sysmem,
 
     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 5c63eaa..af2173a 100644
--- a/hw/spapr_vty.c
+++ b/hw/spapr_vty.c
@@ -54,6 +54,11 @@ void vty_putchars(VIOsPAPRDevice *sdev, uint8_t *buf, int len)
     qemu_chr_fe_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;
@@ -63,8 +68,7 @@ static int spapr_vty_init(VIOsPAPRDevice *sdev)
         exit(1);
     }
 
-    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 ab736e3..9099a06 100644
--- a/hw/strongarm.c
+++ b/hw/strongarm.c
@@ -1200,6 +1200,12 @@ static const MemoryRegionOps strongarm_uart_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
+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);
@@ -1212,11 +1218,7 @@ 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/usb/dev-serial.c b/hw/usb/dev-serial.c
index 47ac8c9..2f8757f 100644
--- a/hw/usb/dev-serial.c
+++ b/hw/usb/dev-serial.c
@@ -414,7 +414,7 @@ static void usb_serial_handle_destroy(USBDevice *dev)
 {
     USBSerialState *s = (USBSerialState *)dev;
 
-    qemu_chr_add_handlers(s->cs, NULL, NULL, NULL, NULL);
+    qemu_chr_add_handlers(s->cs, NULL, NULL);
 }
 
 static int usb_serial_can_read(void *opaque)
@@ -478,6 +478,12 @@ 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);
@@ -491,8 +497,7 @@ 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);
 
     if (s->cs->opened && !dev->attached) {
diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
index 1406e3f..2ee9ad1 100644
--- a/hw/usb/redirect.c
+++ b/hw/usb/redirect.c
@@ -1227,6 +1227,12 @@ 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
  */
@@ -1288,8 +1294,7 @@ static int usbredir_initfn(USBDevice *udev)
 
     /* Let the backend know we are ready */
     qemu_chr_fe_open(dev->cs);
-    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);
 
     qemu_add_vm_change_state_handler(usbredir_vm_state_change, dev);
     add_boot_device_path(dev->bootindex, &udev->qdev, NULL);
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index 46072a0..dd6f614 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -106,6 +106,12 @@ 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);
@@ -117,8 +123,7 @@ 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);
     }
 
     return 0;
diff --git a/hw/xen_console.c b/hw/xen_console.c
index 44141f8..db1eea5 100644
--- a/hw/xen_console.c
+++ b/hw/xen_console.c
@@ -215,6 +215,11 @@ out:
     return ret;
 }
 
+static const QemuChrHandlers xencons_handlers = {
+    .fd_can_read = xencons_can_receive,
+    .fd_read = xencons_receive,
+};
+
 static int con_initialise(struct XenDevice *xendev)
 {
     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
@@ -241,9 +246,9 @@ static int con_initialise(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,
@@ -260,8 +265,9 @@ static void con_disconnect(struct XenDevice *xendev)
     if (!xendev->dev) {
         return;
     }
-    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 9963982..f5e4cde 100644
--- a/hw/xilinx_uartlite.c
+++ b/hw/xilinx_uartlite.c
@@ -192,6 +192,12 @@ 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);
@@ -204,8 +210,9 @@ static int xilinx_uartlite_init(SysBusDevice *dev)
     sysbus_init_mmio(dev, &s->mmio);
 
     s->chr = qemu_char_get_next_serial();
-    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/include/char/char.h b/include/char/char.h
index c91ce3c..3027cc1 100644
--- a/include/char/char.h
+++ b/include/char/char.h
@@ -225,10 +225,15 @@ void qemu_chr_be_write(CharDriverState *s, uint8_t *buf, int len);
  */
 void qemu_chr_be_event(CharDriverState *s, int event);
 
-void qemu_chr_add_handlers(CharDriverState *s,
-                           IOCanReadHandler *fd_can_read,
-                           IOReadHandler *fd_read,
-                           IOEventHandler *fd_event,
+
+typedef struct QemuChrHandlers {
+    IOCanReadHandler *fd_can_read;
+    IOReadHandler *fd_read;
+    IOHandler *fd_write_unblocked;
+    IOEventHandler *fd_event;
+} QemuChrHandlers;
+
+void qemu_chr_add_handlers(CharDriverState *s, const QemuChrHandlers *handlers,
                            void *opaque);
 
 void qemu_chr_generic_open(CharDriverState *s);
diff --git a/monitor.c b/monitor.c
index 20bd19b..be83dd6 100644
--- a/monitor.c
+++ b/monitor.c
@@ -4701,6 +4701,18 @@ static void sortcmdlist(void)
  * 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;
@@ -4723,14 +4735,12 @@ void monitor_init(CharDriverState *chr, int flags)
     if (monitor_ctrl_mode(mon)) {
         mon->mc = g_malloc0(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_fe_set_echo(chr, true);
 
         json_message_parser_init(&mon->mc->parser, handle_qmp_command);
     } 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 4df550f..2868229 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -595,6 +595,11 @@ 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)
 {
@@ -660,8 +665,7 @@ 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;
 
diff --git a/qemu-char.c b/qemu-char.c
index ac2abeb..0c97bdf 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -192,19 +192,26 @@ void qemu_chr_fe_printf(CharDriverState *s, const char *fmt, ...)
     va_end(ap);
 }
 
+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);
@@ -442,6 +449,12 @@ 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;
@@ -456,8 +469,7 @@ 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/qtest.c b/qtest.c
index 4663a38..eb8e7ef 100644
--- a/qtest.c
+++ b/qtest.c
@@ -416,6 +416,13 @@ static void qtest_event(void *opaque, int event)
     }
 }
 
+static const QemuChrHandlers test_handlers = {
+    .fd_can_read = qtest_can_read,
+    .fd_read = qtest_read,
+    .fd_event = qtest_event,
+};
+
+
 int qtest_init(void)
 {
     CharDriverState *chr;
@@ -425,7 +432,7 @@ int qtest_init(void)
     configure_icount("0");
     chr = qemu_chr_new("qtest", qtest_chrdev, NULL);
 
-    qemu_chr_add_handlers(chr, qtest_can_read, qtest_read, qtest_event, chr);
+    qemu_chr_add_handlers(chr, &test_handlers, chr);
     qemu_chr_fe_set_echo(chr, true);
 
     inbuf = g_string_new("");