On Thu, 16 Oct 2014 14:59:40 -0400 Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> wrote: > Hi Greg, > > This patch series: > 1. removes stale code from the controlling tty handling functions > 2. relocates the ctty functions to eliminate forward declarations > 3. fixes several unsafe races when setting the controlling tty > 4. eliminates holding tty_mutex as a necessary condition of > setting the controlling terminal > > #4 is part of an overall effort to reduce the tty_mutex footprint. > > Unfortunately, this series does not fix two other race conditions: > 1. disassociate_ctty()/no_tty() does not teardown the tty<->process > associations atomically wrt job control, so it is possible to > observe spurious error conditions from job control (tty_check_change() > and job_control()). I'm looking into inverting the lock order of > tty->ctrl_lock and tsk->sighand->siglock() to see if holding ctrl_lock > is a suitable solution for atomic teardown. Especially now that > ctrl_lock is not used for flow control anymore :) > 2. task_pgrp() and task_session() are used unsafely. These fixes > will be clearer after #1 is fixed. Reviewed-by: Alan Cox <alan@xxxxxxxxxxxxxxx> I can't prove entirely to my satisfaction that the claim in #9 is true in the presence of simultaenous hangups opens and setsid but the locking appears to be correct for the cases I was trying to figure out anyway. Makes my head hurt just reviewing bits of this so thanks for doing all this work ! -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
