Err,
close(-ENOMEM);
What's that going to close? Hint: you _can't_ close a descriptor that
failed to open, since you don't have a descriptor to close. You can
only try to close an error code, but that's not going to make it anywhere
near the kernel driver level.
> I am assuming
> that the tty layer that talks to the serial driver calls rs_close().
Correct.
> The same thing applies to the code below. I think that the open routine
> should instead set tty->driver_data to NULL upon failure.
Here's an example why that'd be real bad:
1. process A opens /dev/ttyS0 as a normal device. This initialises
tty->driver_data.
2. process B tries to open /dev/cua0
3. process B fails with -EBUSY since the normal device is open and active
(see block_til_ready)
4. since rs_open failed, we set tty->driver_data to be NULL (note that this
is the same tty device pointer as (1) above.
5. process A writes to /dev/ttyS0
6. rs_write does the following:
struct async_struct *info = (struct async_struct *)tty->driver_data;
7. Oops.
-- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/