Re: PATCH (RFC): Rework the 8250 console fix

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Tue, May 02, 2006 at 03:05:02PM +0100, David Woodhouse wrote:
> On Tue, 2006-05-02 at 15:09 +0100, Alan Cox wrote:
> > There are two questions that I think make this an RFC not a final
> > patch
> > 
> > 1.      Should this be pushed up into serial/serial_core.c for all chips. 
> 
> Yes, I think it probably should. It's icky enough that we want one copy
> of it only.

That'd mean we have to add extra methods:

void uart_console_write(struct uart_port *port, const char *s,
                        unsigned int count,
                        void (*putchar)(struct uart_port *, int),
			void *(*pre_write)(struct uart_port *),
			void (*post_write)(struct uart_port *, void *));

where the pre-write places data into some kind of driver specific
structure which is allocated by some weird method, and post_write
restores this information.

Why are these driver specific?  Review all the users of uart_console_write
and you'll find that there's many different requirements for what is
done both before and after the uart_console_write method, most of
which should arguably fall under such a lock.

And I think that calling kmalloc() from within an oops (to allocate the
memory to pass the current state between pre and post write methods)
would be very bad news.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core