Re: [Qemu-devel] [PATCH v2 9/9] char: avoid chardevice direct access

[Marc-André Lureau]

On Fri, May 19, 2017 at 4:53 PM Anton Nefedov <address@hidden>
wrote:

> frontends should avoid accessing CharDriver struct where possible
>
> Signed-off-by: Anton Nefedov <address@hidden>
> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>

I would move this patch up in the series, otherwise looks good


> ---
>  chardev/char.c              | 5 +++++
>  gdbstub.c                   | 2 +-
>  hw/arm/strongarm.c          | 2 +-
>  hw/char/cadence_uart.c      | 2 +-
>  hw/char/debugcon.c          | 2 +-
>  hw/char/escc.c              | 6 +++---
>  hw/char/exynos4210_uart.c   | 2 +-
>  hw/char/grlib_apbuart.c     | 2 +-
>  hw/char/ipoctal232.c        | 2 +-
>  hw/char/parallel.c          | 2 +-
>  hw/char/sclpconsole-lm.c    | 2 +-
>  hw/char/sclpconsole.c       | 2 +-
>  hw/char/sh_serial.c         | 2 +-
>  hw/char/spapr_vty.c         | 2 +-
>  hw/char/terminal3270.c      | 2 +-
>  hw/char/xen_console.c       | 2 +-
>  hw/ipmi/ipmi_bmc_extern.c   | 2 +-
>  hw/misc/ivshmem.c           | 4 ++--
>  hw/usb/ccid-card-passthru.c | 4 ++--
>  hw/usb/dev-serial.c         | 5 ++---
>  hw/usb/redirect.c           | 5 ++---
>  include/sysemu/char.h       | 7 +++++++
>  net/filter-mirror.c         | 2 +-
>  23 files changed, 39 insertions(+), 29 deletions(-)
>
> diff --git a/chardev/char.c b/chardev/char.c
> index 36d6f36..e43d840 100644
> --- a/chardev/char.c
> +++ b/chardev/char.c
> @@ -494,6 +494,11 @@ bool qemu_chr_fe_backend_connected(CharBackend *be)
>      return !!be->chr;
>  }
>
> +bool qemu_chr_fe_backend_open(CharBackend *be)
> +{
> +    return be->chr && be->chr->be_open;
> +}
> +
>  static bool fe_connect(CharBackend *b, Chardev *s, Error **errp)
>  {
>      int tag = 0;
> diff --git a/gdbstub.c b/gdbstub.c
> index 1ac0489..68cbe8a 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -2001,7 +2001,7 @@ int gdbserver_start(const char *device)
>                                     NULL, &error_abort);
>          monitor_init(mon_chr, 0);
>      } else {
> -        if (qemu_chr_fe_get_driver(&s->chr)) {
> +        if (qemu_chr_fe_backend_connected(&s->chr)) {
>              object_unparent(OBJECT(qemu_chr_fe_get_driver(&s->chr)));
>          }
>          mon_chr = s->mon_chr;
> diff --git a/hw/arm/strongarm.c b/hw/arm/strongarm.c
> index bec093d..9d7cf21 100644
> --- a/hw/arm/strongarm.c
> +++ b/hw/arm/strongarm.c
> @@ -1105,7 +1105,7 @@ static void strongarm_uart_tx(void *opaque)
>
>      if (s->utcr3 & UTCR3_LBM) /* loopback */ {
>          strongarm_uart_receive(s, &s->tx_fifo[s->tx_start], 1);
> -    } else if (qemu_chr_fe_get_driver(&s->chr)) {
> +    } else if (qemu_chr_fe_backend_connected(&s->chr)) {
>          /* XXX this blocks entire thread. Rewrite to use
>           * qemu_chr_fe_write and background I/O callbacks */
>          qemu_chr_fe_write_all(&s->chr, &s->tx_fifo[s->tx_start], 1);
> diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
> index 71867b3..19636c0 100644
> --- a/hw/char/cadence_uart.c
> +++ b/hw/char/cadence_uart.c
> @@ -278,7 +278,7 @@ static gboolean cadence_uart_xmit(GIOChannel *chan,
> GIOCondition cond,
>      int ret;
>
>      /* instant drain the fifo when there's no back-end */
> -    if (!qemu_chr_fe_get_driver(&s->chr)) {
> +    if (!qemu_chr_fe_backend_connected(&s->chr)) {
>          s->tx_count = 0;
>          return FALSE;
>      }
> diff --git a/hw/char/debugcon.c b/hw/char/debugcon.c
> index 6d95297..bd0d4f0 100644
> --- a/hw/char/debugcon.c
> +++ b/hw/char/debugcon.c
> @@ -87,7 +87,7 @@ static const MemoryRegionOps debugcon_ops = {
>
>  static void debugcon_realize_core(DebugconState *s, Error **errp)
>  {
> -    if (!qemu_chr_fe_get_driver(&s->chr)) {
> +    if (!qemu_chr_fe_backend_connected(&s->chr)) {
>          error_setg(errp, "Can't create debugcon device, empty char
> device");
>          return;
>      }
> diff --git a/hw/char/escc.c b/hw/char/escc.c
> index aa882b6..dbbeb4a 100644
> --- a/hw/char/escc.c
> +++ b/hw/char/escc.c
> @@ -416,7 +416,7 @@ static void escc_update_parameters(ChannelState *s)
>      int speed, parity, data_bits, stop_bits;
>      QEMUSerialSetParams ssp;
>
> -    if (!qemu_chr_fe_get_driver(&s->chr) || s->type != ser)
> +    if (!qemu_chr_fe_backend_connected(&s->chr) || s->type != ser)
>          return;
>
>      if (s->wregs[W_TXCTRL1] & TXCTRL1_PAREN) {
> @@ -556,7 +556,7 @@ static void escc_mem_write(void *opaque, hwaddr addr,
>          trace_escc_mem_writeb_data(CHN_C(s), val);
>          s->tx = val;
>          if (s->wregs[W_TXCTRL2] & TXCTRL2_TXEN) { // tx enabled
> -            if (qemu_chr_fe_get_driver(&s->chr)) {
> +            if (qemu_chr_fe_backend_connected(&s->chr)) {
>                  /* XXX this blocks entire thread. Rewrite to use
>                   * qemu_chr_fe_write and background I/O callbacks */
>                  qemu_chr_fe_write_all(&s->chr, &s->tx, 1);
> @@ -1012,7 +1012,7 @@ static void escc_realize(DeviceState *dev, Error
> **errp)
>                            ESCC_SIZE << s->it_shift);
>
>      for (i = 0; i < 2; i++) {
> -        if (qemu_chr_fe_get_driver(&s->chn[i].chr)) {
> +        if (qemu_chr_fe_backend_connected(&s->chn[i].chr)) {
>              s->chn[i].clock = s->frequency / 2;
>              qemu_chr_fe_set_handlers(&s->chn[i].chr, serial_can_receive,
>                                       serial_receive1, serial_event, NULL,
> diff --git a/hw/char/exynos4210_uart.c b/hw/char/exynos4210_uart.c
> index 7ef4ea5..2b0576c 100644
> --- a/hw/char/exynos4210_uart.c
> +++ b/hw/char/exynos4210_uart.c
> @@ -379,7 +379,7 @@ static void exynos4210_uart_write(void *opaque, hwaddr
> offset,
>          break;
>
>      case UTXH:
> -        if (qemu_chr_fe_get_driver(&s->chr)) {
> +        if (qemu_chr_fe_backend_connected(&s->chr)) {
>              s->reg[I_(UTRSTAT)] &= ~(UTRSTAT_TRANSMITTER_EMPTY |
>                      UTRSTAT_Tx_BUFFER_EMPTY);
>              ch = (uint8_t)val;
> diff --git a/hw/char/grlib_apbuart.c b/hw/char/grlib_apbuart.c
> index 610a317..1cb9026 100644
> --- a/hw/char/grlib_apbuart.c
> +++ b/hw/char/grlib_apbuart.c
> @@ -201,7 +201,7 @@ static void grlib_apbuart_write(void *opaque, hwaddr
> addr,
>      case DATA_OFFSET:
>      case DATA_OFFSET + 3:       /* When only one byte write */
>          /* Transmit when character device available and transmitter
> enabled */
> -        if (qemu_chr_fe_get_driver(&uart->chr) &&
> +        if (qemu_chr_fe_backend_connected(&uart->chr) &&
>              (uart->control & UART_TRANSMIT_ENABLE)) {
>              c = value & 0xFF;
>              /* XXX this blocks entire thread. Rewrite to use
> diff --git a/hw/char/ipoctal232.c b/hw/char/ipoctal232.c
> index 734e42c..b5ada43 100644
> --- a/hw/char/ipoctal232.c
> +++ b/hw/char/ipoctal232.c
> @@ -542,7 +542,7 @@ static void ipoctal_realize(DeviceState *dev, Error
> **errp)
>          ch->ipoctal = s;
>
>          /* Redirect IP-Octal channels to host character devices */
> -        if (qemu_chr_fe_get_driver(&ch->dev)) {
> +        if (qemu_chr_fe_backend_connected(&ch->dev)) {
>              qemu_chr_fe_set_handlers(&ch->dev, hostdev_can_receive,
>                                       hostdev_receive, hostdev_event,
>                                       NULL, ch, NULL, true);
> diff --git a/hw/char/parallel.c b/hw/char/parallel.c
> index c71a4a0..b3ed117 100644
> --- a/hw/char/parallel.c
> +++ b/hw/char/parallel.c
> @@ -512,7 +512,7 @@ static void parallel_isa_realizefn(DeviceState *dev,
> Error **errp)
>      int base;
>      uint8_t dummy;
>
> -    if (!qemu_chr_fe_get_driver(&s->chr)) {
> +    if (!qemu_chr_fe_backend_connected(&s->chr)) {
>          error_setg(errp, "Can't create parallel device, empty char
> device");
>          return;
>      }
> diff --git a/hw/char/sclpconsole-lm.c b/hw/char/sclpconsole-lm.c
> index ed1e2c5..ff54d19 100644
> --- a/hw/char/sclpconsole-lm.c
> +++ b/hw/char/sclpconsole-lm.c
> @@ -195,7 +195,7 @@ static int write_console_data(SCLPEvent *event, const
> uint8_t *buf, int len)
>  {
>      SCLPConsoleLM *scon = SCLPLM_CONSOLE(event);
>
> -    if (!qemu_chr_fe_get_driver(&scon->chr)) {
> +    if (!qemu_chr_fe_backend_connected(&scon->chr)) {
>          /* If there's no backend, we can just say we consumed all data. */
>          return len;
>      }
> diff --git a/hw/char/sclpconsole.c b/hw/char/sclpconsole.c
> index 9a65010..7e23d09 100644
> --- a/hw/char/sclpconsole.c
> +++ b/hw/char/sclpconsole.c
> @@ -163,7 +163,7 @@ static ssize_t write_console_data(SCLPEvent *event,
> const uint8_t *buf,
>  {
>      SCLPConsole *scon = SCLP_CONSOLE(event);
>
> -    if (!qemu_chr_fe_get_driver(&scon->chr)) {
> +    if (!qemu_chr_fe_backend_connected(&scon->chr)) {
>          /* If there's no backend, we can just say we consumed all data. */
>          return len;
>      }
> diff --git a/hw/char/sh_serial.c b/hw/char/sh_serial.c
> index c352337..868773f 100644
> --- a/hw/char/sh_serial.c
> +++ b/hw/char/sh_serial.c
> @@ -110,7 +110,7 @@ static void sh_serial_write(void *opaque, hwaddr offs,
>          }
>          return;
>      case 0x0c: /* FTDR / TDR */
> -        if (qemu_chr_fe_get_driver(&s->chr)) {
> +        if (qemu_chr_fe_backend_connected(&s->chr)) {
>              ch = val;
>              /* XXX this blocks entire thread. Rewrite to use
>               * qemu_chr_fe_write and background I/O callbacks */
> diff --git a/hw/char/spapr_vty.c b/hw/char/spapr_vty.c
> index 9cdc0e0..6d1ccff 100644
> --- a/hw/char/spapr_vty.c
> +++ b/hw/char/spapr_vty.c
> @@ -78,7 +78,7 @@ static void spapr_vty_realize(VIOsPAPRDevice *sdev,
> Error **errp)
>  {
>      VIOsPAPRVTYDevice *dev = VIO_SPAPR_VTY_DEVICE(sdev);
>
> -    if (!qemu_chr_fe_get_driver(&dev->chardev)) {
> +    if (!qemu_chr_fe_backend_connected(&dev->chardev)) {
>          error_setg(errp, "chardev property not set");
>          return;
>      }
> diff --git a/hw/char/terminal3270.c b/hw/char/terminal3270.c
> index 943a0f3..62803e5 100644
> --- a/hw/char/terminal3270.c
> +++ b/hw/char/terminal3270.c
> @@ -239,7 +239,7 @@ static int write_payload_3270(EmulatedCcw3270Device
> *dev, uint8_t cmd,
>              return 0;
>          }
>      }
> -    if (!qemu_chr_fe_get_driver(&t->chr)) {
> +    if (!qemu_chr_fe_backend_connected(&t->chr)) {
>          /* We just say we consumed all data if there's no backend. */
>          return count;
>      }
> diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
> index cb7975f..b066176 100644
> --- a/hw/char/xen_console.c
> +++ b/hw/char/xen_console.c
> @@ -150,7 +150,7 @@ static void xencons_send(struct XenConsole *con)
>      ssize_t len, size;
>
>      size = con->buffer.size - con->buffer.consumed;
> -    if (qemu_chr_fe_get_driver(&con->chr)) {
> +    if (qemu_chr_fe_backend_connected(&con->chr)) {
>          len = qemu_chr_fe_write(&con->chr,
>                                  con->buffer.data + con->buffer.consumed,
>                                  size);
> diff --git a/hw/ipmi/ipmi_bmc_extern.c b/hw/ipmi/ipmi_bmc_extern.c
> index 6f2339d..0ca9e92 100644
> --- a/hw/ipmi/ipmi_bmc_extern.c
> +++ b/hw/ipmi/ipmi_bmc_extern.c
> @@ -447,7 +447,7 @@ static void ipmi_bmc_extern_realize(DeviceState *dev,
> Error **errp)
>  {
>      IPMIBmcExtern *ibe = IPMI_BMC_EXTERN(dev);
>
> -    if (!qemu_chr_fe_get_driver(&ibe->chr)) {
> +    if (!qemu_chr_fe_backend_connected(&ibe->chr)) {
>          error_setg(errp, "IPMI external bmc requires chardev attribute");
>          return;
>      }
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index e2dece8..a1be4bb 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -1130,7 +1130,7 @@ static void ivshmem_doorbell_realize(PCIDevice *dev,
> Error **errp)
>  {
>      IVShmemState *s = IVSHMEM_COMMON(dev);
>
> -    if (!qemu_chr_fe_get_driver(&s->server_chr)) {
> +    if (!qemu_chr_fe_backend_connected(&s->server_chr)) {
>          error_setg(errp, "You must specify a 'chardev'");
>          return;
>      }
> @@ -1259,7 +1259,7 @@ static void ivshmem_realize(PCIDevice *dev, Error
> **errp)
>                       " or ivshmem-doorbell instead");
>      }
>
> -    if (!!qemu_chr_fe_get_driver(&s->server_chr) + !!s->shmobj != 1) {
> +    if (qemu_chr_fe_backend_connected(&s->server_chr) + !!s->shmobj != 1)
> {
>          error_setg(errp, "You must specify either 'shm' or 'chardev'");
>          return;
>      }
> diff --git a/hw/usb/ccid-card-passthru.c b/hw/usb/ccid-card-passthru.c
> index 9ace5ac..c0f8acd 100644
> --- a/hw/usb/ccid-card-passthru.c
> +++ b/hw/usb/ccid-card-passthru.c
> @@ -325,7 +325,7 @@ static void passthru_apdu_from_guest(
>  {
>      PassthruState *card = PASSTHRU_CCID_CARD(base);
>
> -    if (!qemu_chr_fe_get_driver(&card->cs)) {
> +    if (!qemu_chr_fe_backend_connected(&card->cs)) {
>          printf("ccid-passthru: no chardev, discarding apdu length %d\n",
> len);
>          return;
>      }
> @@ -346,7 +346,7 @@ static int passthru_initfn(CCIDCardState *base)
>
>      card->vscard_in_pos = 0;
>      card->vscard_in_hdr = 0;
> -    if (qemu_chr_fe_get_driver(&card->cs)) {
> +    if (qemu_chr_fe_backend_connected(&card->cs)) {
>          DPRINTF(card, D_INFO, "initing chardev\n");
>          qemu_chr_fe_set_handlers(&card->cs,
>              ccid_card_vscard_can_read,
> diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c
> index e6b2c7c..7aa7290 100644
> --- a/hw/usb/dev-serial.c
> +++ b/hw/usb/dev-serial.c
> @@ -483,13 +483,12 @@ static void usb_serial_realize(USBDevice *dev, Error
> **errp)
>  {
>      USBSerialState *s = USB_SERIAL_DEV(dev);
>      Error *local_err = NULL;
> -    Chardev *chr = qemu_chr_fe_get_driver(&s->cs);
>
>      usb_desc_create_serial(dev);
>      usb_desc_init(dev);
>      dev->auto_attach = 0;
>
> -    if (!chr) {
> +    if (!qemu_chr_fe_backend_connected(&s->cs)) {
>          error_setg(errp, "Property chardev is required");
>          return;
>      }
> @@ -504,7 +503,7 @@ static void usb_serial_realize(USBDevice *dev, Error
> **errp)
>                               usb_serial_event, NULL, s, NULL, true);
>      usb_serial_handle_reset(dev);
>
> -    if (chr->be_open && !dev->attached) {
> +    if (qemu_chr_fe_backend_open(&s->cs) && !dev->attached) {
>          usb_device_attach(dev, &error_abort);
>      }
>  }
> diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
> index 1e9bf69..6992d92 100644
> --- a/hw/usb/redirect.c
> +++ b/hw/usb/redirect.c
> @@ -273,10 +273,9 @@ static gboolean usbredir_write_unblocked(GIOChannel
> *chan, GIOCondition cond,
>  static int usbredir_write(void *priv, uint8_t *data, int count)
>  {
>      USBRedirDevice *dev = priv;
> -    Chardev *chr = qemu_chr_fe_get_driver(&dev->cs);
>      int r;
>
> -    if (!chr->be_open) {
> +    if (!qemu_chr_fe_backend_open(&dev->cs)) {
>          return 0;
>      }
>
> @@ -1366,7 +1365,7 @@ static void usbredir_realize(USBDevice *udev, Error
> **errp)
>      USBRedirDevice *dev = USB_REDIRECT(udev);
>      int i;
>
> -    if (!qemu_chr_fe_get_driver(&dev->cs)) {
> +    if (!qemu_chr_fe_backend_connected(&dev->cs)) {
>          error_setg(errp, QERR_MISSING_PARAMETER, "chardev");
>          return;
>      }
> diff --git a/include/sysemu/char.h b/include/sysemu/char.h
> index fa21535..e1a0e52 100644
> --- a/include/sysemu/char.h
> +++ b/include/sysemu/char.h
> @@ -418,6 +418,13 @@ Chardev *qemu_chr_fe_get_driver(CharBackend *be);
>  bool qemu_chr_fe_backend_connected(CharBackend *be);
>
>  /**
> + * @qemu_chr_fe_backend_open:
> + *
> + * Returns true if chardevice associated with @be is open.
> + */
> +bool qemu_chr_fe_backend_open(CharBackend *be);
> +
> +/**
>   * @qemu_chr_fe_deinit:
>   *
>   * Dissociate the CharBackend from the Chardev.
> diff --git a/net/filter-mirror.c b/net/filter-mirror.c
> index 06321d7..72a6077 100644
> --- a/net/filter-mirror.c
> +++ b/net/filter-mirror.c
> @@ -163,7 +163,7 @@ static ssize_t
> filter_redirector_receive_iov(NetFilterState *nf,
>      MirrorState *s = FILTER_REDIRECTOR(nf);
>      int ret;
>
> -    if (qemu_chr_fe_get_driver(&s->chr_out)) {
> +    if (qemu_chr_fe_backend_connected(&s->chr_out)) {
>          ret = filter_mirror_send(&s->chr_out, iov, iovcnt);
>          if (ret) {
>              error_report("filter_mirror_send failed(%s)", strerror(-ret));
> --
> 2.7.4
>
>
> --
Marc-André Lureau