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 ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel