Messages in this thread | | | Date | Tue, 11 Jul 2017 11:39:13 +0100 | From | Okash Khawaja <> | Subject | Re: [patch] staging: speakup: safely close tty |
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Hi,
On Mon, Jul 10, 2017 at 12:55:44PM +0100, Alan Cox wrote: > On Fri, 7 Jul 2017 20:13:01 +0100 > Okash Khawaja <okash.khawaja@gmail.com> wrote: > > > Speakup opens tty using tty_open_by_driver. When closing, it calls > > tty_ldisc_release but doesn't close and remove the tty itself. As a > > result, that tty cannot then be opened from user space. This patch calls > > tty_release_struct which ensures that tty is safely removed and freed > > up. It also calls tty_ldisc_release, so speakup doesn't need to call it. > > > > This patch also unregisters N_SPEAKUP. It is registered when a speakup > > module is loaded. > > What happens if after you register it someone assigns that ldisc to > another tty as well ? > > You should register the ldisc when the relevant module is initialized and > release it only when the module is unloaded. That way the module ref > counts will handle cases where someone uses the ldisc with something else. Sorry if I misunderstood it. That's what we do here. spk_ttyio_initialise_ldisc is called separately for each module (e.g. speakup_apollo, speakup_ltlk etc) when it is loaded. spk_ttyio_release is also called separately for each module when it is unloaded. The ldisc stays around until the last of the modules is unloaded.
> > I'd also btw strongly recommend putting the ldisc and the speakup tty > driver as different modules. Sure, that makes sense. I will do that following these patches.
Thanks, Okash
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