Amit Shah <amit.shah@xxxxxxxxxx> writes:
> Returning EMFILE (process has too many open files) is incorrect to
> indicate a port is already open by another process. Use EBUSY for that.
>
> This does change what we report to userspace, but I believe userspace
> can look at it this way: it gets EBUSY, a new error code, instead of
> EMFILE. It's still an error, and that's not changing.
>
> Reported-by: Mateusz Guzik <mguzik@xxxxxxxxxx>
> Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
> ---
> Rusty, is this OK? It's a change for the userspace, so is it considered
> breakage? OTOH the current return value is obviously wrong,
Yes, I agree. I don't know of anyone testing for EMFILE particularly,
so this is OK.
Applied,
Rusty.
>
> 'Broken' userspace code could be relying on the exact error type
> (current EMFILE) to detect if other processes are using the same file,
> that's the only thing I can think of where this change can break
> existing userspace. But is that a strong enough reason to not fix this?
>
>
> drivers/char/virtio_console.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index ce5f3fc..b94be04 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -1040,7 +1040,7 @@ static int port_fops_open(struct inode *inode, struct file *filp)
> spin_lock_irq(&port->inbuf_lock);
> if (port->guest_connected) {
> spin_unlock_irq(&port->inbuf_lock);
> - ret = -EMFILE;
> + ret = -EBUSY;
> goto out;
> }
>
> --
> 1.8.1.4
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