Re: [Qemu-devel] [PATCH] cadence_uart: check for serial backend before using it.

[Frederic Konrad <fred.konrad@greensocs.com>]

On 16/07/2014 05:48, Peter Crosthwaite wrote:
> On Wed, Jul 16, 2014 at 1:18 AM,  <fred.konrad@greensocs.com> wrote:
>> From: KONRAD Frederic <fred.konrad@greensocs.com>
>>
>> This checks that s->chr is not NULL before using it.
>>
>> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
>> ---
>>   hw/char/cadence_uart.c | 15 +++++++++++----
>>   1 file changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
>> index dbbc167..a5736cb 100644
>> --- a/hw/char/cadence_uart.c
>> +++ b/hw/char/cadence_uart.c
>> @@ -175,8 +175,10 @@ static void uart_send_breaks(UartState *s)
>>   {
>>       int break_enabled = 1;
>>
>> -    qemu_chr_fe_ioctl(s->chr, CHR_IOCTL_SERIAL_SET_BREAK,
>> -                               &break_enabled);
>> +    if (s->chr) {
>> +        qemu_chr_fe_ioctl(s->chr, CHR_IOCTL_SERIAL_SET_BREAK,
>> +                                   &break_enabled);
>> +    }
>>   }
>>
>>   static void uart_parameters_setup(UartState *s)
>> @@ -227,7 +229,9 @@ static void uart_parameters_setup(UartState *s)
>>
>>       packet_size += ssp.data_bits + ssp.stop_bits;
>>       s->char_tx_time = (get_ticks_per_sec() / ssp.speed) * packet_size;
>> -    qemu_chr_fe_ioctl(s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp);
>> +    if (s->chr) {
>> +        qemu_chr_fe_ioctl(s->chr, CHR_IOCTL_SERIAL_SET_PARAMS, &ssp);
>> +    }
>>   }
>>
>>   static int uart_can_receive(void *opaque)
>> @@ -295,6 +299,7 @@ static gboolean cadence_uart_xmit(GIOChannel *chan, GIOCondition cond,
>>       /* instant drain the fifo when there's no back-end */
>>       if (!s->chr) {
>>           s->tx_count = 0;
>> +        return FALSE;
> Is this needed? With s->tx_count forced to 0 in the NULL dev case,
> won't the next if trigger immediately and return?

True,
I'll make this change and resend.

Thanks,
Fred

>
> 300     if (!s->tx_count) {
> 301         return FALSE;
> 302     }
>
> With this hunk dropped,
>
> Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
>
> And recommended for 2.1.
>
> Regards,
> Peter
>
>>       }
>>
>>       if (!s->tx_count) {
>> @@ -375,7 +380,9 @@ static void uart_read_rx_fifo(UartState *s, uint32_t *c)
>>           *c = s->rx_fifo[rx_rpos];
>>           s->rx_count--;
>>
>> -        qemu_chr_accept_input(s->chr);
>> +        if (s->chr) {
>> +            qemu_chr_accept_input(s->chr);
>> +        }
>>       } else {
>>           *c = 0;
>>       }
>> --
>> 1.9.0
>>
>>