On (20/09/01 14:01), Artem Savkov wrote:
[..]
> It looks like the commit was aimed to protect tty_insert_flip_string and
> there is no need for tty_flip_buffer_push to be under this lock.
>
[..]
> @@ -120,10 +120,10 @@ static int pty_write(struct tty_struct *tty, const
> unsigned char *buf, int c)
> spin_lock_irqsave(&to->port->lock, flags);
> /* Stuff the data into the input queue of the other end */
> c = tty_insert_flip_string(to->port, buf, c);
> + spin_unlock_irqrestore(&to->port->lock, flags);
> /* And shovel */
> if (c)
> tty_flip_buffer_push(to->port);
> - spin_unlock_irqrestore(&to->port->lock, flags);
Performing unprotected
smp_store_release(&buf->tail->commit, buf->tail->used);
does not look safe to me.
This path can be called concurrently - "pty_write vs console's IRQ handler
(TX/RX)", for instance.
Doing this
queue_work(system_unbound_wq, &buf->work);
outside of port->lock scope also sounds like possible concurrent data
modification.
I'm not sure I see how this patch is safe.
-ss
