[PATCH 02/36] ACPI: LPIT: move to use bus_get_dev_root()

[PATCH 02/36] ACPI: LPIT: move to use bus_get_dev_root()

[Greg Kroah-Hartman]

Direct access to the struct bus_type dev_root pointer is going away soon
so replace that with a call to bus_get_dev_root() instead, which is what
it is there for.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Note, this is a patch that is a prepatory cleanup as part of a larger
series of patches that is working on resolving some old driver core
design mistakes.  It will build and apply cleanly on top of 6.3-rc2 on
its own, but I'd prefer if I could take it through my driver-core tree
so that the driver core changes can be taken through there for 6.4-rc1.

 drivers/acpi/acpi_lpit.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/acpi_lpit.c b/drivers/acpi/acpi_lpit.c
index 3843d2576d3f..73b5c4800150 100644
--- a/drivers/acpi/acpi_lpit.c
+++ b/drivers/acpi/acpi_lpit.c
@@ -98,6 +98,8 @@ EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
 static void lpit_update_residency(struct lpit_residency_info *info,
 				 struct acpi_lpit_native *lpit_native)
 {
+	struct device *dev_root = bus_get_dev_root(&cpu_subsys);
+
 	info->frequency = lpit_native->counter_frequency ?
 				lpit_native->counter_frequency : tsc_khz * 1000;
 	if (!info->frequency)
@@ -111,15 +113,18 @@ static void lpit_update_residency(struct lpit_residency_info *info,
 			return;
 
 		/* Silently fail, if cpuidle attribute group is not present */
-		sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
-					&dev_attr_low_power_idle_system_residency_us.attr,
-					"cpuidle");
+		if (dev_root)
+			sysfs_add_file_to_group(&dev_root->kobj,
+						&dev_attr_low_power_idle_system_residency_us.attr,
+						"cpuidle");
 	} else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
 		/* Silently fail, if cpuidle attribute group is not present */
-		sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
-					&dev_attr_low_power_idle_cpu_residency_us.attr,
-					"cpuidle");
+		if (dev_root)
+			sysfs_add_file_to_group(&dev_root->kobj,
+						&dev_attr_low_power_idle_cpu_residency_us.attr,
+						"cpuidle");
 	}
+	put_device(dev_root);
 }
 
 static void lpit_process(u64 begin, u64 end)
-- 
2.39.2

Re: [PATCH 02/36] ACPI: LPIT: move to use bus_get_dev_root()

[Rafael J. Wysocki]

On Mon, Mar 13, 2023 at 7:29 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> Direct access to the struct bus_type dev_root pointer is going away soon
> so replace that with a call to bus_get_dev_root() instead, which is what
> it is there for.
>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Len Brown <lenb@kernel.org>
> Cc: linux-acpi@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> Note, this is a patch that is a prepatory cleanup as part of a larger
> series of patches that is working on resolving some old driver core
> design mistakes.  It will build and apply cleanly on top of 6.3-rc2 on
> its own, but I'd prefer if I could take it through my driver-core tree
> so that the driver core changes can be taken through there for 6.4-rc1.
>
>  drivers/acpi/acpi_lpit.c | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/acpi_lpit.c b/drivers/acpi/acpi_lpit.c
> index 3843d2576d3f..73b5c4800150 100644
> --- a/drivers/acpi/acpi_lpit.c
> +++ b/drivers/acpi/acpi_lpit.c
> @@ -98,6 +98,8 @@ EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
>  static void lpit_update_residency(struct lpit_residency_info *info,
>                                  struct acpi_lpit_native *lpit_native)
>  {
> +       struct device *dev_root = bus_get_dev_root(&cpu_subsys);
> +

This can return here right away if dev_root is NULL, because it will
not do anything useful in that case anyway.

>         info->frequency = lpit_native->counter_frequency ?
>                                 lpit_native->counter_frequency : tsc_khz * 1000;
>         if (!info->frequency)
> @@ -111,15 +113,18 @@ static void lpit_update_residency(struct lpit_residency_info *info,
>                         return;
>
>                 /* Silently fail, if cpuidle attribute group is not present */
> -               sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
> -                                       &dev_attr_low_power_idle_system_residency_us.attr,
> -                                       "cpuidle");
> +               if (dev_root)
> +                       sysfs_add_file_to_group(&dev_root->kobj,
> +                                               &dev_attr_low_power_idle_system_residency_us.attr,
> +                                               "cpuidle");
>         } else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
>                 /* Silently fail, if cpuidle attribute group is not present */
> -               sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
> -                                       &dev_attr_low_power_idle_cpu_residency_us.attr,
> -                                       "cpuidle");
> +               if (dev_root)
> +                       sysfs_add_file_to_group(&dev_root->kobj,
> +                                               &dev_attr_low_power_idle_cpu_residency_us.attr,
> +                                               "cpuidle");
>         }
> +       put_device(dev_root);
>  }
>
>  static void lpit_process(u64 begin, u64 end)
> --
> 2.39.2
>

Re: [PATCH 02/36] ACPI: LPIT: move to use bus_get_dev_root()

[Greg Kroah-Hartman]

On Mon, Mar 13, 2023 at 07:43:22PM +0100, Rafael J. Wysocki wrote:
> On Mon, Mar 13, 2023 at 7:29 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > Direct access to the struct bus_type dev_root pointer is going away soon
> > so replace that with a call to bus_get_dev_root() instead, which is what
> > it is there for.
> >
> > Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> > Cc: Len Brown <lenb@kernel.org>
> > Cc: linux-acpi@vger.kernel.org
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > ---
> > Note, this is a patch that is a prepatory cleanup as part of a larger
> > series of patches that is working on resolving some old driver core
> > design mistakes.  It will build and apply cleanly on top of 6.3-rc2 on
> > its own, but I'd prefer if I could take it through my driver-core tree
> > so that the driver core changes can be taken through there for 6.4-rc1.
> >
> >  drivers/acpi/acpi_lpit.c | 17 +++++++++++------
> >  1 file changed, 11 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/acpi/acpi_lpit.c b/drivers/acpi/acpi_lpit.c
> > index 3843d2576d3f..73b5c4800150 100644
> > --- a/drivers/acpi/acpi_lpit.c
> > +++ b/drivers/acpi/acpi_lpit.c
> > @@ -98,6 +98,8 @@ EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
> >  static void lpit_update_residency(struct lpit_residency_info *info,
> >                                  struct acpi_lpit_native *lpit_native)
> >  {
> > +       struct device *dev_root = bus_get_dev_root(&cpu_subsys);
> > +
> 
> This can return here right away if dev_root is NULL, because it will
> not do anything useful in that case anyway.

Thanks for the review of these, I'll redo some of them and send out a
v2 of them next week.

greg k-h

[PATCH v2 02/19] ACPI: LPIT: move to use bus_get_dev_root()

[Greg Kroah-Hartman]

Direct access to the struct bus_type dev_root pointer is going away soon
so replace that with a call to bus_get_dev_root() instead, which is what
it is there for.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
v2: - change logic to test for dev_root at the beginning of the function
      and error out then based on review comments from Rafael.
    - fix error handling for ioremap() call to properly drop the
      reference on dev_root if it failed.

 drivers/acpi/acpi_lpit.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/acpi_lpit.c b/drivers/acpi/acpi_lpit.c
index 3843d2576d3f..c5598b6d5db8 100644
--- a/drivers/acpi/acpi_lpit.c
+++ b/drivers/acpi/acpi_lpit.c
@@ -98,6 +98,12 @@ EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
 static void lpit_update_residency(struct lpit_residency_info *info,
 				 struct acpi_lpit_native *lpit_native)
 {
+	struct device *dev_root = bus_get_dev_root(&cpu_subsys);
+
+	/* Silently fail, if cpuidle attribute group is not present */
+	if (!dev_root)
+		return;
+
 	info->frequency = lpit_native->counter_frequency ?
 				lpit_native->counter_frequency : tsc_khz * 1000;
 	if (!info->frequency)
@@ -108,18 +114,18 @@ static void lpit_update_residency(struct lpit_residency_info *info,
 		info->iomem_addr = ioremap(info->gaddr.address,
 						   info->gaddr.bit_width / 8);
 		if (!info->iomem_addr)
-			return;
+			goto exit;
 
-		/* Silently fail, if cpuidle attribute group is not present */
-		sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
+		sysfs_add_file_to_group(&dev_root->kobj,
 					&dev_attr_low_power_idle_system_residency_us.attr,
 					"cpuidle");
 	} else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
-		/* Silently fail, if cpuidle attribute group is not present */
-		sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
+		sysfs_add_file_to_group(&dev_root->kobj,
 					&dev_attr_low_power_idle_cpu_residency_us.attr,
 					"cpuidle");
 	}
+exit:
+	put_device(dev_root);
 }
 
 static void lpit_process(u64 begin, u64 end)
-- 
2.40.0

Re: [PATCH v2 02/19] ACPI: LPIT: move to use bus_get_dev_root()

[Rafael J. Wysocki]

On Wed, Mar 22, 2023 at 9:36 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> Direct access to the struct bus_type dev_root pointer is going away soon
> so replace that with a call to bus_get_dev_root() instead, which is what
> it is there for.
>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Len Brown <lenb@kernel.org>
> Cc: linux-acpi@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
> v2: - change logic to test for dev_root at the beginning of the function
>       and error out then based on review comments from Rafael.
>     - fix error handling for ioremap() call to properly drop the
>       reference on dev_root if it failed.
>
>  drivers/acpi/acpi_lpit.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/acpi_lpit.c b/drivers/acpi/acpi_lpit.c
> index 3843d2576d3f..c5598b6d5db8 100644
> --- a/drivers/acpi/acpi_lpit.c
> +++ b/drivers/acpi/acpi_lpit.c
> @@ -98,6 +98,12 @@ EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
>  static void lpit_update_residency(struct lpit_residency_info *info,
>                                  struct acpi_lpit_native *lpit_native)
>  {
> +       struct device *dev_root = bus_get_dev_root(&cpu_subsys);
> +
> +       /* Silently fail, if cpuidle attribute group is not present */
> +       if (!dev_root)
> +               return;
> +
>         info->frequency = lpit_native->counter_frequency ?
>                                 lpit_native->counter_frequency : tsc_khz * 1000;
>         if (!info->frequency)
> @@ -108,18 +114,18 @@ static void lpit_update_residency(struct lpit_residency_info *info,
>                 info->iomem_addr = ioremap(info->gaddr.address,
>                                                    info->gaddr.bit_width / 8);
>                 if (!info->iomem_addr)
> -                       return;
> +                       goto exit;
>
> -               /* Silently fail, if cpuidle attribute group is not present */
> -               sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
> +               sysfs_add_file_to_group(&dev_root->kobj,
>                                         &dev_attr_low_power_idle_system_residency_us.attr,
>                                         "cpuidle");
>         } else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
> -               /* Silently fail, if cpuidle attribute group is not present */
> -               sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
> +               sysfs_add_file_to_group(&dev_root->kobj,
>                                         &dev_attr_low_power_idle_cpu_residency_us.attr,
>                                         "cpuidle");
>         }
> +exit:
> +       put_device(dev_root);
>  }
>
>  static void lpit_process(u64 begin, u64 end)
> --
> 2.40.0
>