[PATCH] Drivers: hv: vmbus: Fix harmless building warnings without CONFIG_PM

[PATCH] Drivers: hv: vmbus: Fix harmless building warnings without CONFIG_PM

[Dexuan Cui]

If CONFIG_PM is not set, we can comment out these functions to avoid the
below warnings:

drivers/hv/vmbus_drv.c:2208:12: warning: ‘vmbus_bus_resume’ defined but not used [-Wunused-function]
drivers/hv/vmbus_drv.c:2128:12: warning: ‘vmbus_bus_suspend’ defined but not used [-Wunused-function]
drivers/hv/vmbus_drv.c:937:12: warning: ‘vmbus_resume’ defined but not used [-Wunused-function]
drivers/hv/vmbus_drv.c:918:12: warning: ‘vmbus_suspend’ defined but not used [-Wunused-function]

Fixes: 271b2224d42f ("Drivers: hv: vmbus: Implement suspend/resume for VSC drivers for hibernation")
Fixes: f53335e3289f ("Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/hv/vmbus_drv.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 391f0b225c9a..8bfb36695413 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -912,6 +912,7 @@ static void vmbus_shutdown(struct device *child_device)
 		drv->shutdown(dev);
 }
 
+#ifdef CONFIG_PM
 /*
  * vmbus_suspend - Suspend a vmbus device
  */
@@ -949,6 +950,7 @@ static int vmbus_resume(struct device *child_device)
 
 	return drv->resume(dev);
 }
+#endif /* CONFIG_PM */
 
 /*
  * vmbus_device_release - Final callback release of the vmbus child device
@@ -1070,6 +1072,7 @@ void vmbus_on_msg_dpc(unsigned long data)
 	vmbus_signal_eom(msg, message_type);
 }
 
+#ifdef CONFIG_PM
 /*
  * Fake RESCIND_CHANNEL messages to clean up hv_sock channels by force for
  * hibernation, because hv_sock connections can not persist across hibernation.
@@ -1105,6 +1108,7 @@ static void vmbus_force_channel_rescinded(struct vmbus_channel *channel)
 		      vmbus_connection.work_queue,
 		      &ctx->work);
 }
+#endif /* CONFIG_PM */
 
 /*
  * Direct callback for channels using other deferred processing
@@ -2125,6 +2129,7 @@ static int vmbus_acpi_add(struct acpi_device *device)
 	return ret_val;
 }
 
+#ifdef CONFIG_PM
 static int vmbus_bus_suspend(struct device *dev)
 {
 	struct vmbus_channel *channel, *sc;
@@ -2247,6 +2252,7 @@ static int vmbus_bus_resume(struct device *dev)
 
 	return 0;
 }
+#endif /* CONFIG_PM */
 
 static const struct acpi_device_id vmbus_acpi_device_ids[] = {
 	{"VMBUS", 0},
-- 
2.19.1

Re: [PATCH] Drivers: hv: vmbus: Fix harmless building warnings without CONFIG_PM

[Arnd Bergmann]

On Thu, Sep 19, 2019 at 7:19 AM Dexuan Cui <decui@microsoft.com> wrote:
>
> If CONFIG_PM is not set, we can comment out these functions to avoid the
> below warnings:
>
> drivers/hv/vmbus_drv.c:2208:12: warning: ‘vmbus_bus_resume’ defined but not used [-Wunused-function]
> drivers/hv/vmbus_drv.c:2128:12: warning: ‘vmbus_bus_suspend’ defined but not used [-Wunused-function]
> drivers/hv/vmbus_drv.c:937:12: warning: ‘vmbus_resume’ defined but not used [-Wunused-function]
> drivers/hv/vmbus_drv.c:918:12: warning: ‘vmbus_suspend’ defined but not used [-Wunused-function]
>
> Fixes: 271b2224d42f ("Drivers: hv: vmbus: Implement suspend/resume for VSC drivers for hibernation")
> Fixes: f53335e3289f ("Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation")
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>

I think this will still produce a warning if CONFIG_PM is set but
CONFIG_PM_SLEEP is not, possibly in other configurations as
well.

      Arnd

RE: [PATCH] Drivers: hv: vmbus: Fix harmless building warnings without CONFIG_PM

[Dexuan Cui]

> Sent: Thursday, September 19, 2019 5:11 AM
> On Thu, Sep 19, 2019 at 7:19 AM Dexuan Cui <decui@microsoft.com> wrote:
> >
> > If CONFIG_PM is not set, we can comment out these functions to avoid the
> > below warnings:
> >
> > drivers/hv/vmbus_drv.c:2208:12: warning: ‘vmbus_bus_resume’ defined
> but not used [-Wunused-function]
> > drivers/hv/vmbus_drv.c:2128:12: warning: ‘vmbus_bus_suspend’ defined
> but not used [-Wunused-function]
> > drivers/hv/vmbus_drv.c:937:12: warning: ‘vmbus_resume’ defined but not
> used [-Wunused-function]
> > drivers/hv/vmbus_drv.c:918:12: warning: ‘vmbus_suspend’ defined but not
> used [-Wunused-function]
> >
> > Fixes: 271b2224d42f ("Drivers: hv: vmbus: Implement suspend/resume for
> VSC drivers for hibernation")
> > Fixes: f53335e3289f ("Drivers: hv: vmbus: Suspend/resume the vmbus itself
> for hibernation")
> > Reported-by: Arnd Bergmann <arnd@arndb.de>
> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> 
> I think this will still produce a warning if CONFIG_PM is set but
> CONFIG_PM_SLEEP is not, possibly in other configurations as
> well.
> 
>  Arnd

You're correct. Thanks! 

I'll use " #ifdef CONFIG_PM_SLEEP ... #endif" instead.

The mentioned functions are only used in the micros
SET_NOIRQ_SYSTEM_SLEEP_PM_OPS, which is empty if CONFIG_PM_SLEEP
is not defined. So it looks to me using "#ifdef CONFIG_PM_SLEEP ..." should
resolve the issue.

BTW, CONFIG_PM_SLEEP depends on CONFIG_PM, so if CONFIG_PM is not
defined, CONFIG_PM_SLEEP is not defined either.

Thanks,
-- Dexuan

Re: [PATCH] Drivers: hv: vmbus: Fix harmless building warnings without CONFIG_PM

[Arnd Bergmann]

On Thu, Sep 19, 2019 at 11:38 PM Dexuan Cui <decui@microsoft.com> wrote:
> > Sent: Thursday, September 19, 2019 5:11 AM
> > On Thu, Sep 19, 2019 at 7:19 AM Dexuan Cui <decui@microsoft.com> wrote:

> > I think this will still produce a warning if CONFIG_PM is set but
> > CONFIG_PM_SLEEP is not, possibly in other configurations as
> > well.
>
> You're correct. Thanks!
>
> I'll use " #ifdef CONFIG_PM_SLEEP ... #endif" instead.
>
> The mentioned functions are only used in the micros
> SET_NOIRQ_SYSTEM_SLEEP_PM_OPS, which is empty if CONFIG_PM_SLEEP
> is not defined. So it looks to me using "#ifdef CONFIG_PM_SLEEP ..." should
> resolve the issue.

Probably, yes. There are sometimes surprising effects, such as when one of the
functions inside of the #ifdef call another function that is otherwise unused.

I would normally try to build a few hundred randconfig builds to be fairly sure
of a change like this, or use __maybe_unused like most other drivers do here.

       Arnd

RE: [PATCH] Drivers: hv: vmbus: Fix harmless building warnings without CONFIG_PM

[Dexuan Cui]

> From: Arnd Bergmann <arnd@arndb.de>
> Sent: Friday, September 20, 2019 12:33 AM
> On Thu, Sep 19, 2019 at 11:38 PM Dexuan Cui <decui@microsoft.com> wrote:
> > > Sent: Thursday, September 19, 2019 5:11 AM
> > > On Thu, Sep 19, 2019 at 7:19 AM Dexuan Cui <decui@microsoft.com>
> wrote:
> 
> > > I think this will still produce a warning if CONFIG_PM is set but
> > > CONFIG_PM_SLEEP is not, possibly in other configurations as
> > > well.
> >
> > You're correct. Thanks!
> >
> > I'll use " #ifdef CONFIG_PM_SLEEP ... #endif" instead.
> >
> > The mentioned functions are only used in the micros
> > SET_NOIRQ_SYSTEM_SLEEP_PM_OPS, which is empty if CONFIG_PM_SLEEP
> > is not defined. So it looks to me using "#ifdef CONFIG_PM_SLEEP ..." should
> > resolve the issue.
> 
> Probably, yes. There are sometimes surprising effects, such as when one of the
> functions inside of the #ifdef call another function that is otherwise unused.

I reviewed the related functions again and I believe with the v2 we don't have
such an issue as you described here.
 
> I would normally try to build a few hundred randconfig builds to be fairly sure
> of a change like this, or use __maybe_unused like most other drivers do here.
> 
>        Arnd

I do see a lot of drivers using __maybe_unused, but IMO conditional
compilation is slightly better. In case conditional compilation still has some
unexpected issue, we can always make a further fix. :-)

Thanks,
-- Dexuan