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Re: [Fwd: I/O errors - confusion]
On Thu, 2003-03-20 at 04:48, Nick Garnett wrote:
> Gary Thomas <gary at mlbassoc dot com> writes:
>
> > On Tue, 2003-03-18 at 11:44, Nick Garnett wrote:
> > > Gary Thomas <gary at mlbassoc dot com> writes:
> > >
> > > >
> > > > I agree - either there is data or not and the return code should
> > > > be very clear: EAGAIN means there is none, anything else means
> > > > there was. I think that the code in serial.c you quote should
> > > > return no error when there is data.
> > >
> > > That is exactly my interpretation of what should happen. The only real
> > > question is whether we should make that change, or just fix it in the
> > > fileio code. I would vote for the former, since it results in code
> > > being removed, but we have to be sure we are not breaking anything
> > > else by doing it.
> >
> > I think that this patch fixes it [correctly]:
> >
> > Index: io/serial/current/src/common/serial.c
> > ===================================================================
> > RCS file: /misc/cvsfiles/ecos/packages/io/serial/current/src/common/serial.c,v
> > retrieving revision 1.17
> > diff -u -5 -p -r1.17 serial.c
> > --- io/serial/current/src/common/serial.c 23 May 2002 23:06:27 -0000 1.17
> > +++ io/serial/current/src/common/serial.c 18 Mar 2003 23:37:03 -0000
> > @@ -341,11 +341,11 @@ serial_write(cyg_io_handle_t handle, con
> > #ifdef CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING
> > // Optionally return if configured for non-blocking mode.
> > if (!cbuf->blocking) {
> > *len -= size; // number of characters actually sent
> > cbuf->waiting = false;
> > - res = -EAGAIN;
> > + res = size == 0 ? -EAGAIN : ENOERROR;
> > break;
> > }
> > #endif // CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING
> > cbuf->pending += size; // Have this much more to send [eventually]
> > if( !cyg_drv_cond_wait(&cbuf->wait) )
> > @@ -438,11 +438,11 @@ serial_read(cyg_io_handle_t handle, void
> > size++;
> > } else {
> > #ifdef CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING
> > if (!cbuf->blocking) {
> > *len = size; // characters actually read
> > - res = -EAGAIN;
> > + res = size == 0 ? -EAGAIN : ENOERROR;
> > break;
> > }
> > #endif // CYGOPT_IO_SERIAL_SUPPORT_NONBLOCKING
> > cbuf->waiting = true;
> > #ifdef XX_CYGDBG_DIAG_BUF
> >
> > Comments?
>
> Without actually trying it, that looks OK to me.
>
> You should also be able to take the -EAGAIN tests out of dev_fo_read()
> and dev_fo_write().
I've tested this (with the -EAGAIN tests removed) and it seems
to work just fine. Of course, I still need the VMIN changes
for my program to work. Jonathan, comments please.
--
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Gary Thomas |
MLB Associates | Consulting for the
+1 (970) 229-1963 | Embedded world
http://www.mlbassoc.com/ |
email: <gary at mlbassoc dot com> |
gpg: http://www.chez-thomas.org/gary/gpg_key.asc
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