Possible deadlock in serial.c

[Gary Thomas]

On Wed, 2003-05-21 at 10:15, David Marqvar (DAM) wrote:
> In function
> 
> 	static Cyg_ErrNo 
> 	serial_get_config(cyg_io_handle_t handle, cyg_uint32 key, void
> *xbuf,
>       	            cyg_uint32 *len)
> 	{
> 
> Shouldn't the #ifdef and call to restart_rx( chan, false ); be added to the
> case below?
> 
>     case CYG_IO_GET_CONFIG_SERIAL_INPUT_FLUSH:
>         // Flush any buffered input
>         if (in_cbuf->len == 0) break;  // Nothing to do if not buffered
>         cyg_drv_mutex_lock(&in_cbuf->lock);  // Stop any further input
> processing
>         cyg_drv_dsr_lock();
>         if (in_cbuf->waiting) {
>             in_cbuf->abort = true;
>             cyg_drv_cond_signal(&in_cbuf->wait);
>             in_cbuf->waiting = false;
>         }
>         in_cbuf->get = in_cbuf->put = in_cbuf->nb = 0;  // Flush buffered
> input
>         cyg_drv_dsr_unlock();
>         cyg_drv_mutex_unlock(&in_cbuf->lock);
> #ifdef CYGPKG_IO_SERIAL_FLOW_CONTROL
>         restart_rx( chan, false );
> #endif
>         break;
> 
> 
> If the serial input buffer is full, and the serial device has been told to
> stop rx, the serial driver should restart rx if the input buffer is flushed.
> Otherwise no data will never be received after that, thus no reads to the
> input buffer (through where the rx could be restarted) -> deadlock.
> 
> Or?
> 
> Will your changes to the serial driver (and the headerfile) be committed to
> the 2.0-branch too in a near future?
> (My suggestion)
> 
> Please write back if I should file a patch for this.

This looks reasonable to me and I have applied the change (patch
attached).

I don't think that there will be any patches made to the 2.0 branch
now that it has been "released".

-- 
Gary Thomas <gary@mlbassoc.com>
MLB Associates
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