Messages in this thread | | | Date | Fri, 11 Jun 2010 13:44:55 +0100 | From | Alan Cox <> | Subject | Re: [PATCH] detour TTY driver - now ttyprintk |
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> +/* > + * TTY operations open function. > + */ > +static int tpk_open(struct tty_struct *tty, struct file *filp) > +{ > + struct ttyprintk_port *port = &tpk_port;
You can replace the rest with
return tty_port_open(port, tty, filp); }
> + * TTY operations close function. > + */ > +static void tpk_close(struct tty_struct *tty, struct file *filp) > +{ > + struct ttyprintk_port *port = tty->driver_data;
and tty_port_close(port, tty, filp);
> +}
which saves a lot of work
> + > +/* > + * TTY operations write function. > + */ > +int tpk_write(struct tty_struct *tty, > + const unsigned char *buf, int count) > +{ > + struct ttyprintk_port *port; > + int ret; > + > + port = tty->driver_data; > + > + if (!port) > + return 0; > + > + if (!(port->port.flags & ASYNC_INITIALIZED)) > + return 0;
These two can't happen if you use tty_port_* so it is better to blow up. If you think you may be seeing it occur then use WARN_ON() or similar
> + > + /* exclusive use of tpk_printk within this tty */ > + mutex_lock(&port->port_write_mutex); > + ret = tpk_printk(buf, count); > + mutex_unlock(&port->port_write_mutex);
And this is serialized by the caller (not that having your own lock is any harm)
> +#define TPKRLEV (('e'<<8) | 0) /* Wait for ttyprintk ratelimiting event*/ > +static int tpk_ioctl(struct tty_struct *tty, struct file *file, > + unsigned int cmd, unsigned long arg) > +{ > + struct ttyprintk_port *port; > + > + port = tty->driver_data; > + > + if (!port) > + return -EINVAL; > + > + switch (cmd) { > + case TPKRLEV: > + wait_event_interruptible(ttyprintk_ratelimit_wq, > + (ttyprintk_ratelimit_event != 0));
Ok that wasn't quite what I had in mind.
What I was thinking was needed was this
/* Stop TIOCCONS */ case TIOCCONS: return -EOPNOTSUPP;
only it won't work that way. I'll sort that out in tty_io.c once the driver is happy. That way anything trying to mis-redirect the console will get stopped early which is probably more reliable than a ratelimit ?
> + memset(&tpk_port, 0, sizeof(tpk_port));
It's static so that isn't needed
> + tty_port_init(&tpk_port.port); > + spin_lock_init(&tpk_port.lock);
The one other bit you will need to use the helpers is
struct tty_port_operations null_ops = { };
tpk_port.port->ops = &null_ops;
Alan
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