Messages in this thread | | | Date | Sun, 12 Feb 2012 19:06:11 +0000 | From | Al Viro <> | Subject | Re: your mail |
| |
On Sun, Feb 12, 2012 at 01:40:47PM +0100, Jiri Slaby wrote: > > 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).
Yecchhh... If I'm reading (and grepping) it right, there are only two non-default instance of tty_operations ->shutdown() - pty and vt ones. Lovely... And while we are at it, vt instance is definitely not safe from interrupts - calls console_lock(). Not that it was relevant in this case...
It's probably too late in this case, but I would've called that method ->sync_cleanup(). Assuming I'm not misreading its intent and history...
| |