From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Kees Cook <keescook@chromium.org>
Cc: andrew@lunn.ch, Jason Cooper <jason@lakedaemon.net>,
rtc-linux@googlegroups.com, a.zummo@towertech.it,
LKML <linux-kernel@vger.kernel.org>,
Julia Lawall <julia.lawall@lip6.fr>,
alexandre.belloni@free-electrons.com,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
gregory.clement@free-electrons.com,
Bhumika Goyal <bhumirks@gmail.com>,
sebastian.hesselbarth@gmail.com
Subject: Re: [PATCH] rtc: armada38x: add __ro_after_init to armada38x_rtc_ops
Date: Tue, 3 Jan 2017 21:54:21 +0000 [thread overview]
Message-ID: <20170103215421.GN14217@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20170103213118.GM14217@n2100.armlinux.org.uk>
On Tue, Jan 03, 2017 at 09:31:18PM +0000, Russell King - ARM Linux wrote:
> On Tue, Jan 03, 2017 at 01:18:29PM -0800, Kees Cook wrote:
> > On Mon, Jan 2, 2017 at 6:06 AM, Russell King - ARM Linux
> > <linux@armlinux.org.uk> wrote:
> > > On Mon, Dec 26, 2016 at 05:01:02PM +0530, Bhumika Goyal wrote:
> > >> The object armada38x_rtc_ops of type rtc_class_ops structure is not
> > >> modified after getting initialized by armada38x_rtc_probe. Apart from
> > >> getting referenced in init it is also passed as an argument to the function
> > >> devm_rtc_device_register but this argument is of type const struct
> > >> rtc_class_ops *. Therefore add __ro_after_init to its declaration.
> > >
> > > What I'd prefer here is for the structure to be duplicated, with one
> > > copy having the alarm methods and one which does not. Both can then
> > > be made "const" (so placed into the read-only section at link time)
> > > and the probe function select between the two.
> > >
> > > I think that's a cleaner and better solution, even though it's
> > > slightly larger.
> > >
> > > I'm not a fan of __ro_after_init being used where other solutions are
> > > possible.
> >
> > Can the pointer that points to the struct rtc_class_ops be made ro_after_init?
>
> It's passed into the RTC core code, and probably stored in some dynamically
> allocated object, so probably no. It's the same class of problem as every
> file_operations pointer in the kernel, or the thousand other operations
> structure pointers that a running kernel has.
For the elimination of doubt, this is what I meant in my original email.
As you can see, there's nothing to be marked as __ro_after_init anymore.
drivers/rtc/rtc-armada38x.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/drivers/rtc/rtc-armada38x.c b/drivers/rtc/rtc-armada38x.c
index 9a3f2a6f512e..a4166ccfce36 100644
--- a/drivers/rtc/rtc-armada38x.c
+++ b/drivers/rtc/rtc-armada38x.c
@@ -202,7 +202,7 @@ static irqreturn_t armada38x_rtc_alarm_irq(int irq, void *data)
return IRQ_HANDLED;
}
-static struct rtc_class_ops armada38x_rtc_ops = {
+static const struct rtc_class_ops armada38x_rtc_ops = {
.read_time = armada38x_rtc_read_time,
.set_time = armada38x_rtc_set_time,
.read_alarm = armada38x_rtc_read_alarm,
@@ -210,8 +210,15 @@ static struct rtc_class_ops armada38x_rtc_ops = {
.alarm_irq_enable = armada38x_rtc_alarm_irq_enable,
};
+static const struct rtc_class_ops armada38x_rtc_ops_noirq = {
+ .read_time = armada38x_rtc_read_time,
+ .set_time = armada38x_rtc_set_time,
+ .read_alarm = armada38x_rtc_read_alarm,
+};
+
static __init int armada38x_rtc_probe(struct platform_device *pdev)
{
+ const struct rtc_class_ops *ops;
struct resource *res;
struct armada38x_rtc *rtc;
int ret;
@@ -242,19 +249,22 @@ static __init int armada38x_rtc_probe(struct platform_device *pdev)
0, pdev->name, rtc) < 0) {
dev_warn(&pdev->dev, "Interrupt not available.\n");
rtc->irq = -1;
+ }
+ platform_set_drvdata(pdev, rtc);
+
+ if (rtc->irq != -1) {
+ device_init_wakeup(&pdev->dev, 1);
+ ops = &armada38x_rtc_ops;
+ } else {
/*
* If there is no interrupt available then we can't
* use the alarm
*/
- armada38x_rtc_ops.set_alarm = NULL;
- armada38x_rtc_ops.alarm_irq_enable = NULL;
+ ops = &armada38x_rtc_ops_noirq;
}
- platform_set_drvdata(pdev, rtc);
- if (rtc->irq != -1)
- device_init_wakeup(&pdev->dev, 1);
rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
- &armada38x_rtc_ops, THIS_MODULE);
+ ops, THIS_MODULE);
if (IS_ERR(rtc->rtc_dev)) {
ret = PTR_ERR(rtc->rtc_dev);
dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2017-01-03 21:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-26 11:31 [PATCH] rtc: armada38x: add __ro_after_init to armada38x_rtc_ops Bhumika Goyal
2017-01-02 14:06 ` Russell King - ARM Linux
2017-01-03 21:18 ` Kees Cook
2017-01-03 21:31 ` Russell King - ARM Linux
2017-01-03 21:54 ` Russell King - ARM Linux [this message]
2017-01-04 10:57 ` Julia Lawall
2017-01-04 11:07 ` Alexandre Belloni
2017-01-04 11:43 ` Julia Lawall
2017-01-04 12:14 ` Russell King - ARM Linux
2017-01-04 12:23 ` Julia Lawall
2017-01-04 13:06 ` Russell King - ARM Linux
2017-01-04 13:41 ` Julia Lawall
2017-01-04 21:53 ` Kees Cook
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