Re: [PATCH v2 05/11] chardev: mark explicitly first argument as poisoned

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Aug 04, 2021 at 07:48:42PM +0400, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> Since commit 9894dc0cdcc397ee5b26370bc53da6d360a363c2 "char: convert
> from GIOChannel to QIOChannel", the first argument to the watch callback
> can actually be a QIOChannel, which is not a GIOChannel (but a QEMU
> Object).
> 
> Even though we never used that pointer, change the callback type to warn
> the users. Possibly a better fix later, we may want to store the
> callback and call it from intermediary functions.
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/chardev/char-fe.h | 8 +++++++-
>  chardev/char-fe.c         | 2 +-
>  hw/char/cadence_uart.c    | 2 +-
>  hw/char/cmsdk-apb-uart.c  | 2 +-
>  hw/char/ibex_uart.c       | 2 +-
>  hw/char/nrf51_uart.c      | 2 +-
>  hw/char/serial.c          | 2 +-
>  hw/char/virtio-console.c  | 2 +-
>  hw/usb/redirect.c         | 2 +-
>  hw/virtio/vhost-user.c    | 2 +-
>  monitor/monitor.c         | 2 +-
>  net/vhost-user.c          | 4 ++--
>  12 files changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/include/chardev/char-fe.h b/include/chardev/char-fe.h
> index a553843364..867ef1b3b2 100644
> --- a/include/chardev/char-fe.h
> +++ b/include/chardev/char-fe.h
> @@ -174,6 +174,9 @@ void qemu_chr_fe_set_open(CharBackend *be, int fe_open);
>  void qemu_chr_fe_printf(CharBackend *be, const char *fmt, ...)
>      GCC_FMT_ATTR(2, 3);
>  
> +
> +typedef gboolean (*FEWatchFunc)(void *do_not_use, GIOCondition condition, void *data);
> +
>  /**
>   * qemu_chr_fe_add_watch:
>   * @cond: the condition to poll for
> @@ -188,10 +191,13 @@ void qemu_chr_fe_printf(CharBackend *be, const char *fmt, ...)
>   * Note that you are responsible to update the front-end sources if
>   * you are switching the main context with qemu_chr_fe_set_handlers().
>   *
> + * Warning: DO NOT use the first callback argument (it may be either
> + * a GIOChannel or a QIOChannel, depending on the underlying chardev)
> + *
>   * Returns: the source tag
>   */
>  guint qemu_chr_fe_add_watch(CharBackend *be, GIOCondition cond,
> -                            GIOFunc func, void *user_data);
> +                            FEWatchFunc func, void *user_data);
>  
>  /**
>   * qemu_chr_fe_write:
> diff --git a/chardev/char-fe.c b/chardev/char-fe.c
> index 474715c5a9..7789f7be9c 100644
> --- a/chardev/char-fe.c
> +++ b/chardev/char-fe.c
> @@ -354,7 +354,7 @@ void qemu_chr_fe_set_open(CharBackend *be, int fe_open)
>  }
>  
>  guint qemu_chr_fe_add_watch(CharBackend *be, GIOCondition cond,
> -                            GIOFunc func, void *user_data)
> +                            FEWatchFunc func, void *user_data)
>  {
>      Chardev *s = be->chr;
>      GSource *src;
> diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
> index ceb677bc5a..8ee6f74b8c 100644
> --- a/hw/char/cadence_uart.c
> +++ b/hw/char/cadence_uart.c
> @@ -288,7 +288,7 @@ static void uart_write_rx_fifo(void *opaque, const uint8_t *buf, int size)
>      uart_update_status(s);
>  }
>  
> -static gboolean cadence_uart_xmit(GIOChannel *chan, GIOCondition cond,
> +static gboolean cadence_uart_xmit(GIOChannel *do_not_use, GIOCondition cond,
>                                    void *opaque)

Why is this (and the next 3) left as GIOCondition, when you change others
later on to be void ?

>  {
>      CadenceUARTState *s = opaque;
> diff --git a/hw/char/cmsdk-apb-uart.c b/hw/char/cmsdk-apb-uart.c
> index ba2cbbee3d..b07a9dee4f 100644
> --- a/hw/char/cmsdk-apb-uart.c
> +++ b/hw/char/cmsdk-apb-uart.c
> @@ -191,7 +191,7 @@ static uint64_t uart_read(void *opaque, hwaddr offset, unsigned size)
>  /* Try to send tx data, and arrange to be called back later if
>   * we can't (ie the char backend is busy/blocking).
>   */
> -static gboolean uart_transmit(GIOChannel *chan, GIOCondition cond, void *opaque)
> +static gboolean uart_transmit(GIOChannel *do_not_use, GIOCondition cond, void *opaque)
>  {
>      CMSDKAPBUART *s = CMSDK_APB_UART(opaque);
>      int ret;
> diff --git a/hw/char/ibex_uart.c b/hw/char/ibex_uart.c
> index 6b0c9330bf..e493ea08c0 100644
> --- a/hw/char/ibex_uart.c
> +++ b/hw/char/ibex_uart.c
> @@ -135,7 +135,7 @@ static void ibex_uart_receive(void *opaque, const uint8_t *buf, int size)
>      ibex_uart_update_irqs(s);
>  }
>  
> -static gboolean ibex_uart_xmit(GIOChannel *chan, GIOCondition cond,
> +static gboolean ibex_uart_xmit(GIOChannel *do_not_use, GIOCondition cond,
>                                 void *opaque)
>  {
>      IbexUartState *s = opaque;
> diff --git a/hw/char/nrf51_uart.c b/hw/char/nrf51_uart.c
> index 045ca5fa40..0b89b0eae4 100644
> --- a/hw/char/nrf51_uart.c
> +++ b/hw/char/nrf51_uart.c
> @@ -75,7 +75,7 @@ static uint64_t uart_read(void *opaque, hwaddr addr, unsigned int size)
>      return r;
>  }
>  
> -static gboolean uart_transmit(GIOChannel *chan, GIOCondition cond, void *opaque)
> +static gboolean uart_transmit(GIOChannel *do_not_use, GIOCondition cond, void *opaque)
>  {
>      NRF51UARTState *s = NRF51_UART(opaque);
>      int r;
> diff --git a/hw/char/serial.c b/hw/char/serial.c
> index bc2e322970..7061aacbce 100644
> --- a/hw/char/serial.c
> +++ b/hw/char/serial.c
> @@ -220,7 +220,7 @@ static void serial_update_msl(SerialState *s)
>      }
>  }
>  
> -static gboolean serial_watch_cb(GIOChannel *chan, GIOCondition cond,
> +static gboolean serial_watch_cb(void *do_not_use, GIOCondition cond,
>                                  void *opaque)
>  {
>      SerialState *s = opaque;
> diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c
> index 6b132caa29..dd5a02e339 100644
> --- a/hw/char/virtio-console.c
> +++ b/hw/char/virtio-console.c
> @@ -38,7 +38,7 @@ struct VirtConsole {
>   * Callback function that's called from chardevs when backend becomes
>   * writable.
>   */
> -static gboolean chr_write_unblocked(GIOChannel *chan, GIOCondition cond,
> +static gboolean chr_write_unblocked(void *do_not_use, GIOCondition cond,
>                                      void *opaque)
>  {
>      VirtConsole *vcon = opaque;
> diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
> index 1ec909a63a..5f0ef9cb3b 100644
> --- a/hw/usb/redirect.c
> +++ b/hw/usb/redirect.c
> @@ -270,7 +270,7 @@ static int usbredir_read(void *priv, uint8_t *data, int count)
>      return count;
>  }
>  
> -static gboolean usbredir_write_unblocked(GIOChannel *chan, GIOCondition cond,
> +static gboolean usbredir_write_unblocked(void *do_not_use, GIOCondition cond,
>                                           void *opaque)
>  {
>      USBRedirDevice *dev = opaque;
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 29ea2b4fce..aec6cc1990 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -303,7 +303,7 @@ struct vhost_user_read_cb_data {
>      int ret;
>  };
>  
> -static gboolean vhost_user_read_cb(GIOChannel *source, GIOCondition condition,
> +static gboolean vhost_user_read_cb(void *do_not_use, GIOCondition condition,
>                                     gpointer opaque)
>  {
>      struct vhost_user_read_cb_data *data = opaque;
> diff --git a/monitor/monitor.c b/monitor/monitor.c
> index b90c0f4051..46a171bca6 100644
> --- a/monitor/monitor.c
> +++ b/monitor/monitor.c
> @@ -156,7 +156,7 @@ static inline bool monitor_is_hmp_non_interactive(const Monitor *mon)
>  
>  static void monitor_flush_locked(Monitor *mon);
>  
> -static gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond,
> +static gboolean monitor_unblocked(void *do_not_use, GIOCondition cond,
>                                    void *opaque)
>  {
>      Monitor *mon = opaque;
> diff --git a/net/vhost-user.c b/net/vhost-user.c
> index ffbd94d944..6adfcd623a 100644
> --- a/net/vhost-user.c
> +++ b/net/vhost-user.c
> @@ -208,8 +208,8 @@ static NetClientInfo net_vhost_user_info = {
>          .set_vnet_le = vhost_user_set_vnet_endianness,
>  };
>  
> -static gboolean net_vhost_user_watch(GIOChannel *chan, GIOCondition cond,
> -                                           void *opaque)
> +static gboolean net_vhost_user_watch(void *do_not_use, GIOCondition cond,
> +                                     void *opaque)
>  {
>      NetVhostUserState *s = opaque;
>  
> -- 
> 2.32.0.264.g75ae10bc75
> 

Regards,
Daniel
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