Messages in this thread | | | Date | Sun, 12 Feb 2012 13:40:47 +0100 | From | Jiri Slaby <> | Subject | Re: your mail |
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On 02/12/2012 02:02 AM, Al Viro wrote: > On Sun, Feb 12, 2012 at 01:21:10AM +0100, Richard Weinberger wrote: >> +++ b/arch/um/drivers/line.c >> @@ -19,19 +19,29 @@ static irqreturn_t line_interrupt(int irq, void *data) >> { >> struct chan *chan = data; >> struct line *line = chan->line; >> + struct tty_struct *tty; >> + >> + if (line) { >> + tty = tty_port_tty_get(&line->port); >> + chan_interrupt(&line->chan_list, &line->task, tty, irq); >> + tty_kref_put(tty); >> + } >> >> - if (line) >> - chan_interrupt(&line->chan_list, &line->task, line->tty, irq); >> return IRQ_HANDLED; >> } > > Is tty_kref_put() safe in interrupt? Here it seems to be OK, but in other > callers... More or less at random: drivers/tty/serial/lantiq.c has it > called from lqasc_rx_int(). It seems to be possible to have it end up > calling ->ops->shutdown() and in this case that'd be lqasc_shutdown(). > Which does a bunch of free_irq(), including the ->rx_irq, i.e. the one > we have it called from. Alan?
I'm not Alan, but will reply anyway. Yes, it is safe (unless the driver does something tricky). In the driver you mention, this is uart_ops, called from tty_port_operations' ->shutdown. And that's a different from tty_operations' ->shutdown.
Yes, there are: * tty->ops * tty_port->ops * uart_port->ops
uart_port->ops->shutdown is supposed to tear down interrupts like in lantiq.c. It is called from tty_port->ops->shutdown. And that one is allowed to be called only from user context (tty->ops->close and tty->ops->hangup).
thanks, -- js suse labs
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