From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Johan Hovold <johan@kernel.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>,
Pavel Machek <pavel@ucw.cz>, Dan Murphy <dmurphy@ti.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel@pengutronix.de, linux-serial@vger.kernel.org
Subject: Re: [PATCH v6 2/4] tty: rename tty_kopen() and add new function tty_kopen_shared()
Date: Wed, 19 Feb 2020 17:37:58 +0100 [thread overview]
Message-ID: <20200219163758.5rypsol4n6ucost4@pengutronix.de> (raw)
In-Reply-To: <20200219132113.GD32540@localhost>
On Wed, Feb 19, 2020 at 02:21:13PM +0100, Johan Hovold wrote:
> On Thu, Feb 13, 2020 at 10:15:58AM +0100, Uwe Kleine-König wrote:
> > From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> >
> > Introduce a new function tty_kopen_shared() that yields a struct
> > tty_struct. The semantic difference to tty_kopen() is that the tty is
> > expected to be used already. So rename tty_kopen() to
> > tty_kopen_exclusive() for clearness, adapt the single user and put the
> > common code in a new static helper function.
> >
> > tty_kopen_shared is to be used to implement an LED trigger for tty
> > devices in one of the next patches.
> >
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > ---
>
> > -/**
> > - * tty_kopen - open a tty device for kernel
> > - * @device: dev_t of device to open
> > - *
> > - * Opens tty exclusively for kernel. Performs the driver lookup,
> > - * makes sure it's not already opened and performs the first-time
> > - * tty initialization.
> > - *
> > - * Returns the locked initialized &tty_struct
> > - *
> > - * Claims the global tty_mutex to serialize:
> > - * - concurrent first-time tty initialization
> > - * - concurrent tty driver removal w/ lookup
> > - * - concurrent tty removal from driver table
> > - */
> > -struct tty_struct *tty_kopen(dev_t device)
> > +static struct tty_struct *tty_kopen(dev_t device, int shared)
> > {
> > struct tty_struct *tty;
> > struct tty_driver *driver;
> > @@ -1905,7 +1890,7 @@ struct tty_struct *tty_kopen(dev_t device)
> >
> > /* check whether we're reopening an existing tty */
> > tty = tty_driver_lookup_tty(driver, NULL, index);
> > - if (IS_ERR(tty))
> > + if (IS_ERR(tty) || shared)
>
> So here you skip initialisation and return NULL if the tty isn't already
> in use (e.g. is open) when shared is set.
Which is good, right? If I remember my tests correctly this even works
if the tty isn't opened but just "exists".
> > goto out;
> >
> > if (tty) {
> > @@ -1923,7 +1908,44 @@ struct tty_struct *tty_kopen(dev_t device)
> > tty_driver_kref_put(driver);
> > return tty;
> > }
> > -EXPORT_SYMBOL_GPL(tty_kopen);
> > +
> > +/**
> > + * tty_kopen_exclusive - open a tty device for kernel
> > + * @device: dev_t of device to open
> > + *
> > + * Opens tty exclusively for kernel. Performs the driver lookup,
> > + * makes sure it's not already opened and performs the first-time
> > + * tty initialization.
> > + *
> > + * Returns the locked initialized &tty_struct
> > + *
> > + * Claims the global tty_mutex to serialize:
> > + * - concurrent first-time tty initialization
> > + * - concurrent tty driver removal w/ lookup
> > + * - concurrent tty removal from driver table
> > + */
> > +struct tty_struct *tty_kopen_exclusive(dev_t device)
> > +{
> > + return tty_kopen(device, 0);
> > +}
> > +EXPORT_SYMBOL_GPL(tty_kopen_exclusive);
> > +
> > +/**
> > + * tty_kopen_shared - open a tty device for shared in-kernel use
> > + * @device: dev_t of device to open
> > + *
> > + * Opens an already existing tty
> > + * rnel. Performs the driver lookup,
>
> "rnel"?
>
> > + * makes sure it's not already opened and performs the first-time
> > + * tty initialization.
>
> Yet, you claim to do initialisation here, which isn't the case.
Yeah, wrong (and incomplete) copy of the tty_kopen_exclusive docstring.
> > + *
> > + * Locking is identical to tty_kopen() above.
> > + */
> > +struct tty_struct *tty_kopen_shared(dev_t device)
> > +{
> > + return tty_kopen(device, 1);
> > +}
> > +EXPORT_SYMBOL_GPL(tty_kopen_shared);
>
> This "kopen" naming is unfortunate as the tty isn't really opened by
> either of these functions, but that's not something you introduced.
Ack, will send a v7 with the doc string fixed.
Thanks for taking the time to look over
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
next prev parent reply other threads:[~2020-02-19 16:38 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-13 9:15 [PATCH v6 0/4] leds: trigger: implement a tty trigger Uwe Kleine-König
2020-02-13 9:15 ` [PATCH v6 1/4] lib: new helper kstrtodev_t() Uwe Kleine-König
2020-02-19 19:50 ` Andy Shevchenko
2020-02-20 7:49 ` Uwe Kleine-König
2020-02-20 10:22 ` Andy Shevchenko
2020-02-20 10:57 ` Uwe Kleine-König
2020-02-20 11:46 ` Andy Shevchenko
2020-02-20 11:57 ` Andy Shevchenko
2020-02-20 14:01 ` Uwe Kleine-König
2020-02-21 8:42 ` Andy Shevchenko
2020-02-21 10:53 ` Uwe Kleine-König
2020-04-25 7:07 ` Pavel Machek
2020-02-13 9:15 ` [PATCH v6 2/4] tty: rename tty_kopen() and add new function tty_kopen_shared() Uwe Kleine-König
2020-02-19 13:21 ` Johan Hovold
2020-02-19 16:37 ` Uwe Kleine-König [this message]
2020-02-19 17:17 ` Johan Hovold
2020-02-20 11:04 ` Uwe Kleine-König
2020-02-25 8:55 ` Johan Hovold
2020-02-25 9:05 ` Uwe Kleine-König
2020-02-13 9:15 ` [PATCH v6 3/4] tty: new helper function tty_get_icount() Uwe Kleine-König
2020-02-13 9:16 ` [PATCH v6 4/4] leds: trigger: implement a tty trigger Uwe Kleine-König
2020-02-19 10:52 ` Johan Hovold
2020-02-19 11:03 ` Uwe Kleine-König
2020-02-19 11:19 ` Johan Hovold
2020-02-19 12:48 ` Johan Hovold
2020-02-19 10:40 ` [PATCH v6 0/4] " Greg Kroah-Hartman
2020-02-26 14:02 ` Pavel Machek
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