Re: [flashrom] [PATCH] Break endless loop in serialport_write().

[Idwer Vollering]

2012/11/29 Stefan Tauner <[e-mail]>:
> serialport_write could loop endlessly when used with a seemingly valid port
> that does always return 0 on writes instead of an error.
> Give up after about 125 ms i.e. 250 tries with a period of 500 us.
>
> Signed-off-by: Stefan Tauner <[e-mail]>

Note that this introduces a minor execution slowdown when used with -o/--output.

Acked-by: Idwer Vollering <[e-mail]>
> ---
>  serial.c |   14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/serial.c b/serial.c
> index 7e47dcc..794763e 100644
> --- a/serial.c
> +++ b/serial.c
> @@ -262,6 +262,7 @@ int serialport_write(unsigned char *buf, unsigned int writecnt)
>  #else
>         ssize_t tmp = 0;
>  #endif
> +       unsigned int empty_writes = 250; /* results in a ca. 125ms timeout */
>
> while (writecnt > 0) {
>  #ifdef _WIN32
> @@ -273,9 +274,16 @@ int serialport_write(unsigned char *buf, unsigned int writecnt)
>                         msg_perr("Serial port write error!\n");
>                         return 1;
>                 }
> -               if (!tmp)
> -                       msg_pdbg("Empty write\n");
> -               writecnt -= tmp;
> +               if (!tmp) {
> +                       msg_pdbg2("Empty write\n");
> +                       empty_writes--;
> +                       programmer_delay(500);
> +                       if (empty_writes == 0) {
> +                               msg_perr("Serial port seems dead!\n");
> +                               return 1;
> +                       }
> +               }
> +               writecnt -= tmp;
>                 buf += tmp;
>         }
>
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