Re: [PATCH v24 01/10] drivers/base: refactor cpu.c to use .is_visible()

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I still need to convert the ifdefs within the functions to IS_ENABLED(), my apologies.
eric

On 6/28/23 13:52, Eric DeVolder wrote:
Greg Kroah-Hartman requested that this file use the .is_visible()
method instead of #ifdefs for the attributes in cpu.c.

  static struct attribute *cpu_root_attrs[] = {
  #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
     &dev_attr_probe.attr,
     &dev_attr_release.attr,
  #endif
     &cpu_attrs[0].attr.attr,
     &cpu_attrs[1].attr.attr,
     &cpu_attrs[2].attr.attr,
     &dev_attr_kernel_max.attr,
     &dev_attr_offline.attr,
     &dev_attr_isolated.attr,
  #ifdef CONFIG_NO_HZ_FULL
     &dev_attr_nohz_full.attr,
  #endif
  #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
     &dev_attr_modalias.attr,
  #endif
     NULL
  };

To that end:
  - the .is_visible() method is implemented, and IS_ENABLED(), rather
    than #ifdef, is used to determine the visibility of the attribute.
  - the DEVICE_ATTR() attributes are moved outside of #ifdefs, so that
    those structs are always present for the cpu_root_attrs[].
  - the #ifdefs guarding the attributes in the cpu_root_attrs[] are moved
    to the corresponding callback function; as the callback function must
    exist now that the attribute is always compiled-in (though not
    necessarily visible).

No functionality change intended.

Signed-off-by: Eric DeVolder <eric.devolder@xxxxxxxxxx>
---
  drivers/base/cpu.c | 67 ++++++++++++++++++++++++++++++++++++----------
  1 file changed, 53 insertions(+), 14 deletions(-)

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index c1815b9dae68..75fa46a567a1 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -82,13 +82,14 @@ void unregister_cpu(struct cpu *cpu)
  	per_cpu(cpu_sys_devices, logical_cpu) = NULL;
  	return;
  }
+#endif /* CONFIG_HOTPLUG_CPU */
-#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  static ssize_t cpu_probe_store(struct device *dev,
  			       struct device_attribute *attr,
  			       const char *buf,
  			       size_t count)
  {
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  	ssize_t cnt;
  	int ret;
@@ -100,6 +101,9 @@ static ssize_t cpu_probe_store(struct device *dev, unlock_device_hotplug();
  	return cnt;
+#else
+	return 0;
+#endif
  }
static ssize_t cpu_release_store(struct device *dev,
@@ -107,6 +111,7 @@ static ssize_t cpu_release_store(struct device *dev,
  				 const char *buf,
  				 size_t count)
  {
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  	ssize_t cnt;
  	int ret;
@@ -118,12 +123,13 @@ static ssize_t cpu_release_store(struct device *dev, unlock_device_hotplug();
  	return cnt;
+#else
+	return 0;
+#endif
  }
static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
  static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
-#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
-#endif /* CONFIG_HOTPLUG_CPU */
#ifdef CONFIG_KEXEC
  #include <linux/kexec.h>
@@ -273,14 +279,16 @@ static ssize_t print_cpus_isolated(struct device *dev,
  }
  static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
-#ifdef CONFIG_NO_HZ_FULL
  static ssize_t print_cpus_nohz_full(struct device *dev,
  				    struct device_attribute *attr, char *buf)
  {
+#ifdef CONFIG_NO_HZ_FULL
  	return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));
+#else
+	return 0;
+#endif
  }
  static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
-#endif
static void cpu_device_release(struct device *dev)
  {
@@ -301,12 +309,12 @@ static void cpu_device_release(struct device *dev)
  	 */
  }
-#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
  static ssize_t print_cpu_modalias(struct device *dev,
  				  struct device_attribute *attr,
  				  char *buf)
  {
  	int len = 0;
+#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
  	u32 i;
len += sysfs_emit_at(buf, len,
@@ -322,9 +330,11 @@ static ssize_t print_cpu_modalias(struct device *dev,
  			len += sysfs_emit_at(buf, len, ",%04X", i);
  		}
  	len += sysfs_emit_at(buf, len, "\n");
+#endif
  	return len;
  }
+#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
  static int cpu_uevent(const struct device *dev, struct kobj_uevent_env *env)
  {
  	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
@@ -451,32 +461,61 @@ struct device *cpu_device_create(struct device *parent, void *drvdata,
  }
  EXPORT_SYMBOL_GPL(cpu_device_create);
-#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
  static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
-#endif
static struct attribute *cpu_root_attrs[] = {
-#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  	&dev_attr_probe.attr,
  	&dev_attr_release.attr,
-#endif
  	&cpu_attrs[0].attr.attr,
  	&cpu_attrs[1].attr.attr,
  	&cpu_attrs[2].attr.attr,
  	&dev_attr_kernel_max.attr,
  	&dev_attr_offline.attr,
  	&dev_attr_isolated.attr,
-#ifdef CONFIG_NO_HZ_FULL
  	&dev_attr_nohz_full.attr,
-#endif
-#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
  	&dev_attr_modalias.attr,
-#endif
  	NULL
  };
+static umode_t
+cpu_root_attr_is_visible(struct kobject *kobj,
+			       struct attribute *attr, int unused)
+{
+	umode_t mode = attr->mode;
+
+	if (IS_ENABLED(CONFIG_ARCH_CPU_PROBE_RELEASE)) {
+		if (attr == &dev_attr_probe.attr)
+			return mode;
+		if (attr == &dev_attr_release.attr)
+			return mode;
+	}
+	if (attr == &cpu_attrs[0].attr.attr)
+		return mode;
+	if (attr == &cpu_attrs[1].attr.attr)
+		return mode;
+	if (attr == &cpu_attrs[2].attr.attr)
+		return mode;
+	if (attr == &dev_attr_kernel_max.attr)
+		return mode;
+	if (attr == &dev_attr_offline.attr)
+		return mode;
+	if (attr == &dev_attr_isolated.attr)
+		return mode;
+	if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
+		if (attr == &dev_attr_nohz_full.attr)
+			return mode;
+	}
+	if (IS_ENABLED(CONFIG_GENERIC_CPU_AUTOPROBE)) {
+		if (attr == &dev_attr_modalias.attr)
+			return mode;
+	}
+
+	return 0;
+}
+
  static const struct attribute_group cpu_root_attr_group = {
  	.attrs = cpu_root_attrs,
+	.is_visible = cpu_root_attr_is_visible,
  };
static const struct attribute_group *cpu_root_attr_groups[] = {




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