Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1666767

Re: [PATCH v2 1/8] tty: add a poll() callback in struct tty_operations

Show all headers | View raw

On Wed, Jun 14, 2017 at 4:33 PM, Alan Cox <gnomes@lxorguk.ukuu.org.uk> wrote:
>> That would cut it, but TIOCPKT is too coupled with having a linked tty.
>> I could make acm behave like a pty (accept TIOCPKT and issue the
>> ctrl_status bits), but for that I need n_tty to know that packet does
>> not always mean a linked tty is present, and that in case it isn't we
>> take our own ctrl_status bits instead of the link's. I could write a
>> small (inline?) function to fetch the correct ctrl_status bits and put
>> that in n_tty. Does that make sense?
>
> I think that makes sense, and I would do the job properly rather than do
> a hack with tty->link. Those hacks in the long term never work out the
> best approach.
>
> Alan
Ok, so I'm doing that and everything is great until I got to actually
modifying tty->termios.
I need to modify it from interrupt context (the usb_request's
complete() callback), but modifying the termios requires a
rw_semaphore I can't take.
I could queue_work() to do it, but then I'd have to flush the work
from another non-sleepable context in acm_disconnect() (which runs
under a spinlock).
I can't change the semaphore to a spinlock because some drivers that
use it actually wanna sleep while holding it.
Any ideas?

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH v2 1/8] tty: add a poll() callback in struct tty_operations Tal Shorer <tal.shorer@gmail.com> - 2017-06-13 09:00 +0200
  Re: [PATCH v2 1/8] tty: add a poll() callback in struct  tty_operations Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-06-14 03:20 +0200
    Re: [PATCH v2 1/8] tty: add a poll() callback in struct tty_operations Tal Shorer <tal.shorer@gmail.com> - 2017-06-14 10:30 +0200
      Re: [PATCH v2 1/8] tty: add a poll() callback in struct tty_operations Tal Shorer <tal.shorer@gmail.com> - 2017-06-14 10:30 +0200
      Re: [PATCH v2 1/8] tty: add a poll() callback in struct  tty_operations Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-06-14 15:40 +0200
        Re: [PATCH v2 1/8] tty: add a poll() callback in struct tty_operations Tal Shorer <tal.shorer@gmail.com> - 2017-06-15 16:50 +0200

csiph-web