tty_flip_buffer() from atomic context when low_latency==1

[Grant Edwards <grant.b.edwards@gmail.com>]

I've been looking at various drivers to try to figure out how to
receive a block of serial data in an atomic context.  All the examples
I can find buffer the receive data with calls to
tty_insert_flip_string() or tty_insert_flip_char(), then they call
tty_flip_buffer_push().

But, many drivers appear to call tty_flip_buffer_push() from an atomic
context. If that is done with tty->low_latency==1 it turns into a call
to flush_to_ldisc(), which then calls disc->ops->receive_buf(), which
must not be called from an atomic context.

Is the low_latency flag being forced to 0 somewhere behind the scenes
when tty_flip_buffer_push() is being called from an atomic context?

-- 
Grant Edwards               grant.b.edwards        Yow! I'm receiving a coded
                                  at               message from EUBIE BLAKE!!
                              gmail.com