Messages in this thread | | | Date | Mon, 21 Mar 2011 10:15:41 +0100 | From | Jiri Slaby <> | Subject | Re: 'scheduling while atomic' during ppp connection on 2.6.37.1 and 2.6.38 |
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On 03/20/2011 10:58 PM, Alan Cox wrote: >> + spin_lock_irqsave(&dc->spin_mutex, flags); >> if (port->port.count) >> room = kfifo_avail(&port->fifo_ul); >> - mutex_unlock(&port->tty_sem); >> + spin_unlock_irqrestore(&dc->spin_mutex, flags); > > dc->spin_mutex does not protect port->port.count.
Neither port->tty_sem did.
Anyway is the test needed at all? I.e. could tty->ops->write/chars_in_buffer/ntty_write_room be called with port->port.count == 0 at all?
And the lock should not as well be needed. Kfifo assures atomicity where there is only one reader and one writer which should be the case here. Unless tty->ops->write can be called in parallel. And it should not, that's what's tty->atomic_write_lock for.
thanks, -- js suse labs
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