diff mbox series

[v2,02/12] timekeeping: add API for getting timekeeping_suspended

Message ID 20210928235635.1348330-3-willmcvicker@google.com (mailing list archive)
State Not Applicable, archived
Headers show
Series arm64: Kconfig: Update ARCH_EXYNOS select configs | expand

Commit Message

William McVicker Sept. 28, 2021, 11:56 p.m. UTC
This allows modules to access the value of timekeeping_suspended without
giving them write access to the variable.

Signed-off-by: Will McVicker <willmcvicker@google.com>
---
 include/linux/timekeeping.h |  1 +
 kernel/time/timekeeping.c   | 11 +++++++++++
 2 files changed, 12 insertions(+)

Comments

John Stultz Sept. 29, 2021, 3:42 a.m. UTC | #1
On Tue, Sep 28, 2021 at 4:56 PM Will McVicker <willmcvicker@google.com> wrote:
>
> This allows modules to access the value of timekeeping_suspended without
> giving them write access to the variable.
>

It's important to cover "the why" not "the what" in these commit
messages, so you might add a note as to what code will be the user of
this (the samsung/clk-pll.c code changed later in this series).

thanks
-john
William McVicker Sept. 29, 2021, 8:01 p.m. UTC | #2
On Tue, Sep 28, 2021 at 8:42 PM John Stultz <john.stultz@linaro.org> wrote:
>
> On Tue, Sep 28, 2021 at 4:56 PM Will McVicker <willmcvicker@google.com> wrote:
> >
> > This allows modules to access the value of timekeeping_suspended without
> > giving them write access to the variable.
> >
>
> It's important to cover "the why" not "the what" in these commit
> messages, so you might add a note as to what code will be the user of
> this (the samsung/clk-pll.c code changed later in this series).
>
> thanks
> -john

Thanks John for the tip. I will try to be better at that in the followup.

For this specific patch, I am adding this new API because the Samsung
PLL driver (drivers/clk/samsung/clk-pll.c) currently is using the
variable 'timekeeping_suspended' to detect timeouts before the
clocksource is initialized or timekeeping itself is suspended. My
patch series aims to modularize the Samsung PLL driver. So to keep the
driver's functionality intact, I need to add this additional API.

--Will
John Stultz Sept. 29, 2021, 8:46 p.m. UTC | #3
On Wed, Sep 29, 2021 at 1:01 PM Will McVicker <willmcvicker@google.com> wrote:
> On Tue, Sep 28, 2021 at 8:42 PM John Stultz <john.stultz@linaro.org> wrote:
> > On Tue, Sep 28, 2021 at 4:56 PM Will McVicker <willmcvicker@google.com> wrote:
> > >
> > > This allows modules to access the value of timekeeping_suspended without
> > > giving them write access to the variable.
> > >
> >
> > It's important to cover "the why" not "the what" in these commit
> > messages, so you might add a note as to what code will be the user of
> > this (the samsung/clk-pll.c code changed later in this series).
> >
> > thanks
> > -john
>
> Thanks John for the tip. I will try to be better at that in the followup.

I have to remind myself regularly as well. :)  Apologies if my quick
reply above seemed curt (as it does to me re-reading it now). Wasn't
my intent.

> For this specific patch, I am adding this new API because the Samsung
> PLL driver (drivers/clk/samsung/clk-pll.c) currently is using the
> variable 'timekeeping_suspended' to detect timeouts before the
> clocksource is initialized or timekeeping itself is suspended. My
> patch series aims to modularize the Samsung PLL driver. So to keep the
> driver's functionality intact, I need to add this additional API.

Sounds good!

Another small/medium suggestion:  Since you're adding a new interface
for non-core users of timekeeping_suspended, it might be good to
switch the other users as well (seems like just
drivers/clk/ti/clkctrl.c and kernel/sched/clock.c), then also remove
the extern in include/linux/timekeeping.h (so there's one consistent
method to access it)?  I know it's a sort of scope creep, so apologies
for asking, but it would make the series more attractive if it's not
leaving something for others to clean up later.

thanks
-john
William McVicker Sept. 30, 2021, 6:31 p.m. UTC | #4
Thanks for the suggestion. That makes sense. I'll look into that for
the next version.

--Will

On Wed, Sep 29, 2021 at 1:46 PM John Stultz <john.stultz@linaro.org> wrote:
>
> On Wed, Sep 29, 2021 at 1:01 PM Will McVicker <willmcvicker@google.com> wrote:
> > On Tue, Sep 28, 2021 at 8:42 PM John Stultz <john.stultz@linaro.org> wrote:
> > > On Tue, Sep 28, 2021 at 4:56 PM Will McVicker <willmcvicker@google.com> wrote:
> > > >
> > > > This allows modules to access the value of timekeeping_suspended without
> > > > giving them write access to the variable.
> > > >
> > >
> > > It's important to cover "the why" not "the what" in these commit
> > > messages, so you might add a note as to what code will be the user of
> > > this (the samsung/clk-pll.c code changed later in this series).
> > >
> > > thanks
> > > -john
> >
> > Thanks John for the tip. I will try to be better at that in the followup.
>
> I have to remind myself regularly as well. :)  Apologies if my quick
> reply above seemed curt (as it does to me re-reading it now). Wasn't
> my intent.
>
> > For this specific patch, I am adding this new API because the Samsung
> > PLL driver (drivers/clk/samsung/clk-pll.c) currently is using the
> > variable 'timekeeping_suspended' to detect timeouts before the
> > clocksource is initialized or timekeeping itself is suspended. My
> > patch series aims to modularize the Samsung PLL driver. So to keep the
> > driver's functionality intact, I need to add this additional API.
>
> Sounds good!
>
> Another small/medium suggestion:  Since you're adding a new interface
> for non-core users of timekeeping_suspended, it might be good to
> switch the other users as well (seems like just
> drivers/clk/ti/clkctrl.c and kernel/sched/clock.c), then also remove
> the extern in include/linux/timekeeping.h (so there's one consistent
> method to access it)?  I know it's a sort of scope creep, so apologies
> for asking, but it would make the series more attractive if it's not
> leaving something for others to clean up later.
>
> thanks
> -john
diff mbox series

Patch

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 78a98bdff76d..cdc84421d77b 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -8,6 +8,7 @@ 
 /* Included from linux/ktime.h */
 
 void timekeeping_init(void);
+extern bool timekeeping_is_suspended(void);
 extern int timekeeping_suspended;
 
 /* Architecture timer tick functions: */
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index b348749a9fc6..27873c052e57 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -57,6 +57,17 @@  static struct timekeeper shadow_timekeeper;
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
 
+/**
+ * timekeeping_is_suspended - query for timekeeping_suspended
+ *
+ * Returns the true/false based on the value of timekeeping_suspened.
+ */
+bool timekeeping_is_suspended(void)
+{
+	return timekeeping_suspended ? true : false;
+}
+EXPORT_SYMBOL_GPL(timekeeping_is_suspended);
+
 /**
  * struct tk_fast - NMI safe timekeeper
  * @seq:	Sequence counter for protecting updates. The lowest bit