From: Daniel Starke <[email protected]>
Add support for the TIOCMIWAIT ioctl on the virtual ttys. This enables the
user to wait for virtual modem signals like RING.
Signed-off-by: Daniel Starke <[email protected]>
---
drivers/tty/n_gsm.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 118511c1fa37..48fb7dad44cd 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1542,6 +1542,7 @@ static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
if (brk & 0x01)
tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
dlci->modem_rx = mlines;
+ wake_up_interruptible(&dlci->gsm->event);
}
/**
@@ -3848,6 +3849,35 @@ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
return -EPROTONOSUPPORT;
}
+/**
+ * gsm_wait_modem_change - wait for modem status line change
+ * @dlci: channel
+ * @mask: modem status line bits
+ */
+
+static int gsm_wait_modem_change(struct gsm_dlci *dlci, u32 mask)
+{
+ struct gsm_mux *gsm = dlci->gsm;
+ u32 old = dlci->modem_rx & mask;
+ int ret;
+
+ if (gsm->dead)
+ return -ENODEV;
+
+ do {
+ ret = wait_event_interruptible(gsm->event, gsm->dead
+ || old ^ (dlci->modem_rx & mask));
+ if (ret)
+ return ret;
+ if (dlci->state != DLCI_OPEN)
+ return -EL2NSYNC;
+ if (gsm->dead)
+ return -ENODEV;
+ } while ((old ^ (dlci->modem_rx & mask)) == 0);
+
+ return 0;
+}
+
static bool gsm_carrier_raised(struct tty_port *port)
{
struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
@@ -4107,6 +4137,8 @@ static int gsmtty_ioctl(struct tty_struct *tty,
gsm_destroy_network(dlci);
mutex_unlock(&dlci->mutex);
return 0;
+ case TIOCMIWAIT:
+ return gsm_wait_modem_change(dlci, arg);
default:
return -ENOIOCTLCMD;
}
--
2.34.1
On Wed, Feb 01, 2023 at 09:01:51AM +0100, D. Starke wrote:
> From: Daniel Starke <[email protected]>
>
> Add support for the TIOCMIWAIT ioctl on the virtual ttys. This enables the
> user to wait for virtual modem signals like RING.
>
> Signed-off-by: Daniel Starke <[email protected]>
> ---
> drivers/tty/n_gsm.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> index 118511c1fa37..48fb7dad44cd 100644
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -1542,6 +1542,7 @@ static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
> if (brk & 0x01)
> tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
> dlci->modem_rx = mlines;
> + wake_up_interruptible(&dlci->gsm->event);
> }
>
> /**
> @@ -3848,6 +3849,35 @@ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
> return -EPROTONOSUPPORT;
> }
>
> +/**
> + * gsm_wait_modem_change - wait for modem status line change
No need for tabs.
Or for kernel doc for static functions, but that's not a big deal.
> + * @dlci: channel
> + * @mask: modem status line bits
> + */
> +
No blank line please, didn't checkpatch warn about that?
> +static int gsm_wait_modem_change(struct gsm_dlci *dlci, u32 mask)
> +{
> + struct gsm_mux *gsm = dlci->gsm;
> + u32 old = dlci->modem_rx & mask;
> + int ret;
> +
> + if (gsm->dead)
> + return -ENODEV;
> +
> + do {
> + ret = wait_event_interruptible(gsm->event, gsm->dead
> + || old ^ (dlci->modem_rx & mask));
> + if (ret)
> + return ret;
> + if (dlci->state != DLCI_OPEN)
> + return -EL2NSYNC;
> + if (gsm->dead)
> + return -ENODEV;
> + } while ((old ^ (dlci->modem_rx & mask)) == 0);
No way to break out of the loop if it goes for forever?
thanks,
greg k-h
> > Add support for the TIOCMIWAIT ioctl on the virtual ttys. This enables the
> > user to wait for virtual modem signals like RING.
> >
> > Signed-off-by: Daniel Starke <[email protected]>
> > ---
> > drivers/tty/n_gsm.c | 32 ++++++++++++++++++++++++++++++++
> > 1 file changed, 32 insertions(+)
> >
> > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> > index 118511c1fa37..48fb7dad44cd 100644
> > --- a/drivers/tty/n_gsm.c
> > +++ b/drivers/tty/n_gsm.c
> > @@ -1542,6 +1542,7 @@ static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
> > if (brk & 0x01)
> > tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
> > dlci->modem_rx = mlines;
> > + wake_up_interruptible(&dlci->gsm->event);
> > }
> >
> > /**
> > @@ -3848,6 +3849,35 @@ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
> > return -EPROTONOSUPPORT;
> > }
> >
> > +/**
> > + * gsm_wait_modem_change - wait for modem status line change
>
> No need for tabs.
>
> Or for kernel doc for static functions, but that's not a big deal.
All other functions follow the same style here. Nevertheless, I will
replace the tabs with spaces. Originally, I had planned a code clean-up
after committing all the changes from my original RFC.
> > + * @dlci: channel
> > + * @mask: modem status line bits
> > + */
> > +
>
> No blank line please, didn't checkpatch warn about that?
No, checkpatch did not warn about this and all other functions follow the
same style. I will remove the blank line.
> > +static int gsm_wait_modem_change(struct gsm_dlci *dlci, u32 mask)
> > +{
> > + struct gsm_mux *gsm = dlci->gsm;
> > + u32 old = dlci->modem_rx & mask;
> > + int ret;
> > +
> > + if (gsm->dead)
> > + return -ENODEV;
> > +
> > + do {
> > + ret = wait_event_interruptible(gsm->event, gsm->dead
> > + || old ^ (dlci->modem_rx & mask));
> > + if (ret)
> > + return ret;
> > + if (dlci->state != DLCI_OPEN)
> > + return -EL2NSYNC;
> > + if (gsm->dead)
> > + return -ENODEV;
> > + } while ((old ^ (dlci->modem_rx & mask)) == 0);
>
> No way to break out of the loop if it goes for forever?
I assume that this is the expected behavior for TIOCMIWAIT. The functions
returns if:
- the requested modem signal changed
- the wait function got interrupted (e.g. by a signal)
- the underlying DLCI was closed
- the underlying ldisc device was removed
I can add that the function returns immediate if a mask has been passed
which matches no modem signal if this is preferred?
Best regards,
Daniel Starke
On Wed, Feb 01, 2023 at 09:30:28AM +0000, Starke, Daniel wrote:
> > > Add support for the TIOCMIWAIT ioctl on the virtual ttys. This enables the
> > > user to wait for virtual modem signals like RING.
> > >
> > > Signed-off-by: Daniel Starke <[email protected]>
> > > ---
> > > drivers/tty/n_gsm.c | 32 ++++++++++++++++++++++++++++++++
> > > 1 file changed, 32 insertions(+)
> > >
> > > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> > > index 118511c1fa37..48fb7dad44cd 100644
> > > --- a/drivers/tty/n_gsm.c
> > > +++ b/drivers/tty/n_gsm.c
> > > @@ -1542,6 +1542,7 @@ static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
> > > if (brk & 0x01)
> > > tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
> > > dlci->modem_rx = mlines;
> > > + wake_up_interruptible(&dlci->gsm->event);
> > > }
> > >
> > > /**
> > > @@ -3848,6 +3849,35 @@ static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
> > > return -EPROTONOSUPPORT;
> > > }
> > >
> > > +/**
> > > + * gsm_wait_modem_change - wait for modem status line change
> >
> > No need for tabs.
> >
> > Or for kernel doc for static functions, but that's not a big deal.
>
> All other functions follow the same style here. Nevertheless, I will
> replace the tabs with spaces. Originally, I had planned a code clean-up
> after committing all the changes from my original RFC.
Ah, ok, nevermind then, I didn't see that as it's not in the diffs.
Cleaning up later is fine.
> > > +static int gsm_wait_modem_change(struct gsm_dlci *dlci, u32 mask)
> > > +{
> > > + struct gsm_mux *gsm = dlci->gsm;
> > > + u32 old = dlci->modem_rx & mask;
> > > + int ret;
> > > +
> > > + if (gsm->dead)
> > > + return -ENODEV;
> > > +
> > > + do {
> > > + ret = wait_event_interruptible(gsm->event, gsm->dead
> > > + || old ^ (dlci->modem_rx & mask));
> > > + if (ret)
> > > + return ret;
> > > + if (dlci->state != DLCI_OPEN)
> > > + return -EL2NSYNC;
> > > + if (gsm->dead)
> > > + return -ENODEV;
> > > + } while ((old ^ (dlci->modem_rx & mask)) == 0);
> >
> > No way to break out of the loop if it goes for forever?
>
> I assume that this is the expected behavior for TIOCMIWAIT. The functions
> returns if:
> - the requested modem signal changed
> - the wait function got interrupted (e.g. by a signal)
> - the underlying DLCI was closed
> - the underlying ldisc device was removed
Hm, I guess you are right. But wow, reading that
wait_event_interruptible() condition is crazy, please document that
really well to explain this properly so you will be able to understand
it in a year when you next have to fix it up :)
> I can add that the function returns immediate if a mask has been passed
> which matches no modem signal if this is preferred?
I don't think that would work, try it on some existing serial ports to
see what they do.
thanks,
greg k-h