On Thu, 2013-05-16 at 08:54 -0400, Peter Hurley wrote: > 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? 3.4 > > > 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(). > Thanks for remind, 3.4 haven't tty_port_destroy(), the mainline has changed the way to call tty_buffer_free_all().
> If the concurrent use you're observing is with flush_to_ldisc(), > that should be fixed in current mainline. > Yes, when calling flush_to_ldisc() in Kernel 3.4, we could observe the tty buffer is corrupted, and dummped stack shows that tty_buffer_free_all() was called before. Is it a known issue fixed in old version? would you please tell me related patch to solve this flush_to_ldisc() issue? Thanks very much. Chao -- 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/
