ACPI fixes for 5.13-rc1

- Revent recent commit related to the handling of ACPI power
    resources during initialization, because it turned out to cause
    problems to occur on some systems (Rafael Wysocki).
 
  - Fix potential use-after-free and potential memory leak in the
    ACPI "custom method" debugfs interface (Mark Langsdorf).
 
  - Update ACPI GPIO properties documentation to cover assumptions
    regarding GPIO polarity (Andy Shevchenko).
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Merge tag 'acpi-5.13-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI fixes from Rafael Wysocki:
 "These revert one recent commit that turned out to be problematic,
  address two issues in the ACPI "custom method" interface and update
  GPIO properties documentation.

  Specifics:

   - Revent recent commit related to the handling of ACPI power
     resources during initialization, because it turned out to cause
     problems to occur on some systems (Rafael Wysocki).

   - Fix potential use-after-free and potential memory leak in the ACPI
     "custom method" debugfs interface (Mark Langsdorf).

   - Update ACPI GPIO properties documentation to cover assumptions
     regarding GPIO polarity (Andy Shevchenko)"

* tag 'acpi-5.13-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Revert "ACPI: scan: Turn off unused power resources during initialization"
  ACPI: custom_method: fix a possible memory leak
  ACPI: custom_method: fix potential use-after-free issue
  Documentation: firmware-guide: gpio-properties: Add note to SPI CS case

Documentation/firmware-guide/acpi/gpio-properties.rst

@@ -99,6 +99,12 @@ native::
       }
   }
 
+Note, that historically ACPI has no means of the GPIO polarity and thus
+the SPISerialBus() resource defines it on the per-chip basis. In order
+to avoid a chain of negations, the GPIO polarity is considered being
+Active High. Even for the cases when _DSD() is involved (see the example
+above) the GPIO CS polarity must be defined Active High to avoid ambiguity.
+
 Other supported properties
 ==========================
 

drivers/acpi/custom_method.c

@@ -42,6 +42,8 @@ static ssize_t cm_write(struct file *file, const char __user *user_buf,
 				   sizeof(struct acpi_table_header)))
 			return -EFAULT;
 		uncopied_bytes = max_size = table.length;
+		/* make sure the buf is not allocated */
+		kfree(buf);
 		buf = kzalloc(max_size, GFP_KERNEL);
 		if (!buf)
 			return -ENOMEM;
@@ -55,6 +57,7 @@ static ssize_t cm_write(struct file *file, const char __user *user_buf,
 	    (*ppos + count < count) ||
 	    (count > uncopied_bytes)) {
 		kfree(buf);
+		buf = NULL;
 		return -EINVAL;
 	}
 
@@ -76,7 +79,6 @@ static ssize_t cm_write(struct file *file, const char __user *user_buf,
 		add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
 	}
 
-	kfree(buf);
 	return count;
 }
 

drivers/acpi/internal.h

@@ -142,7 +142,6 @@ int acpi_device_sleep_wake(struct acpi_device *dev,
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state);
 int acpi_power_on_resources(struct acpi_device *device, int state);
 int acpi_power_transition(struct acpi_device *device, int state);
-void acpi_turn_off_unused_power_resources(void);
 
 /* --------------------------------------------------------------------------
                               Device Power Management

drivers/acpi/power.c

@@ -995,7 +995,6 @@ void acpi_resume_power_resources(void)
 
 	mutex_unlock(&power_resource_list_lock);
 }
-#endif
 
 void acpi_turn_off_unused_power_resources(void)
 {
@@ -1016,3 +1015,4 @@ void acpi_turn_off_unused_power_resources(void)
 
 	mutex_unlock(&power_resource_list_lock);
 }
+#endif

drivers/acpi/scan.c

@@ -2359,8 +2359,6 @@ int __init acpi_scan_init(void)
 		}
 	}
 
-	acpi_turn_off_unused_power_resources();
-
 	acpi_scan_initialized = true;
 
  out:

drivers/acpi/sleep.h

@@ -8,6 +8,7 @@ extern struct list_head acpi_wakeup_device_list;
 extern struct mutex acpi_device_lock;
 
 extern void acpi_resume_power_resources(void);
+extern void acpi_turn_off_unused_power_resources(void);
 
 static inline acpi_status acpi_set_waking_vector(u32 wakeup_address)
 {