On 05/16/2013 04:59 AM, channing wrote:
In tty_buffer.c, function tty_buffer_free_all() is used to remove all buffers for a tty, although it's declared that it mustn't be called when the tty is in use, it cannot guarantee that. we can observe some device driver make use it by mistake, for example, while tty device is releasing, the tty data forwarding is not stopped, then it might hit the case that tty buffer is being used while tty_buffer_free_all() free this tty buffer, and finally lead to random error at any places, and it's not clear to debug.
What kernel version?
Although device driver could do better, it's simpler and safer to strengthen protection in the view of tty buffer, by adding a tty->buf.lock in tty_buffer_free_all() to avoid it racing with ongoing tty buffer operations.
Sorry, but this isn't correct. The driver cannot continue to perform i/o concurrently with tty_port_destroy(). If the concurrent use you're observing is with flush_to_ldisc(), that should be fixed in current mainline. Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
