---

yaml
---
r: 141933
b: refs/heads/master
c: a4d5eff
h: refs/heads/master
i:
  141931: 9510154
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2586d5663d0a17d69383acf6110f16a979a07c4e
+refs/heads/master: a4d5effcc73749ee3ebbf578d162905e6fa4e07d

trunk/Documentation/laptops/thinkpad-acpi.txt

@@ -901,6 +901,17 @@ some older ThinkPad models, it is possible to query the status of the
 LED indicators as well.  Newer ThinkPads cannot query the real status
 of the LED indicators.
 
+Because misuse of the LEDs could induce an unaware user to perform
+dangerous actions (like undocking or ejecting a bay device while the
+buses are still active), or mask an important alarm (such as a nearly
+empty battery, or a broken battery), access to most LEDs is
+restricted.
+
+Unrestricted access to all LEDs requires that thinkpad-acpi be
+compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
+Distributions must never enable this option.  Individual users that
+are aware of the consequences are welcome to enabling it.
+
 procfs notes:
 
 The available commands are:

trunk/drivers/platform/x86/Kconfig

@@ -226,6 +226,30 @@ config THINKPAD_ACPI_DEBUG
 
 	  If you are not sure, say N here.
 
+config THINKPAD_ACPI_UNSAFE_LEDS
+	bool "Allow control of important LEDs (unsafe)"
+	depends on THINKPAD_ACPI
+	default n
+	---help---
+	  Overriding LED state on ThinkPads can mask important
+	  firmware alerts (like critical battery condition), or misled
+	  the user into damaging the hardware (undocking or ejecting
+	  the bay while buses are still active), etc.
+
+	  LED control on the ThinkPad is write-only (with very few
+	  exceptions on very ancient models), which makes it
+	  impossible to know beforehand if important information will
+	  be lost when one changes LED state.
+
+	  Users that know what they are doing can enable this option
+	  and the driver will allow control of every LED, including
+	  the ones on the dock stations.
+
+	  Never enable this option on a distribution kernel.
+
+	  Say N here, unless you are building a kernel for your own
+	  use, and need to control the important firmware LEDs.
+
 config THINKPAD_ACPI_DOCK
 	bool "Legacy Docking Station Support"
 	depends on THINKPAD_ACPI

trunk/drivers/platform/x86/thinkpad_acpi.c

@@ -4657,6 +4657,16 @@ static const char * const tpacpi_led_names[TPACPI_LED_NUMLEDS] = {
 	"tpacpi::unknown_led",
 	"tpacpi::standby",
 };
+#define TPACPI_SAFE_LEDS	0x0081U
+
+static inline bool tpacpi_is_led_restricted(const unsigned int led)
+{
+#ifdef CONFIG_THINKPAD_ACPI_UNSAFE_LEDS
+	return false;
+#else
+	return (TPACPI_SAFE_LEDS & (1 << led)) == 0;
+#endif
+}
 
 static int led_get_status(const unsigned int led)
 {
@@ -4694,16 +4704,20 @@ static int led_set_status(const unsigned int led,
 	switch (led_supported) {
 	case TPACPI_LED_570:
 		/* 570 */
-		if (led > 7)
+		if (unlikely(led > 7))
 			return -EINVAL;
+		if (unlikely(tpacpi_is_led_restricted(led)))
+			return -EPERM;
 		if (!acpi_evalf(led_handle, NULL, NULL, "vdd",
 				(1 << led), led_sled_arg1[ledstatus]))
 			rc = -EIO;
 		break;
 	case TPACPI_LED_OLD:
 		/* 600e/x, 770e, 770x, A21e, A2xm/p, T20-22, X20 */
-		if (led > 7)
+		if (unlikely(led > 7))
 			return -EINVAL;
+		if (unlikely(tpacpi_is_led_restricted(led)))
+			return -EPERM;
 		rc = ec_write(TPACPI_LED_EC_HLMS, (1 << led));
 		if (rc >= 0)
 			rc = ec_write(TPACPI_LED_EC_HLBL,
@@ -4714,6 +4728,10 @@ static int led_set_status(const unsigned int led,
 		break;
 	case TPACPI_LED_NEW:
 		/* all others */
+		if (unlikely(led >= TPACPI_LED_NUMLEDS))
+			return -EINVAL;
+		if (unlikely(tpacpi_is_led_restricted(led)))
+			return -EPERM;
 		if (!acpi_evalf(led_handle, NULL, NULL, "vdd",
 				led, led_led_arg1[ledstatus]))
 			rc = -EIO;
@@ -4806,6 +4824,30 @@ static void led_exit(void)
 	kfree(tpacpi_leds);
 }
 
+static int __init tpacpi_init_led(unsigned int led)
+{
+	int rc;
+
+	tpacpi_leds[led].led = led;
+
+	tpacpi_leds[led].led_classdev.brightness_set = &led_sysfs_set;
+	tpacpi_leds[led].led_classdev.blink_set = &led_sysfs_blink_set;
+	if (led_supported == TPACPI_LED_570)
+		tpacpi_leds[led].led_classdev.brightness_get =
+						&led_sysfs_get;
+
+	tpacpi_leds[led].led_classdev.name = tpacpi_led_names[led];
+
+	INIT_WORK(&tpacpi_leds[led].work, led_set_status_worker);
+
+	rc = led_classdev_register(&tpacpi_pdev->dev,
+				&tpacpi_leds[led].led_classdev);
+	if (rc < 0)
+		tpacpi_leds[led].led_classdev.name = NULL;
+
+	return rc;
+}
+
 static int __init led_init(struct ibm_init_struct *iibm)
 {
 	unsigned int i;
@@ -4839,27 +4881,21 @@ static int __init led_init(struct ibm_init_struct *iibm)
 	}
 
 	for (i = 0; i < TPACPI_LED_NUMLEDS; i++) {
-		tpacpi_leds[i].led = i;
-
-		tpacpi_leds[i].led_classdev.brightness_set = &led_sysfs_set;
-		tpacpi_leds[i].led_classdev.blink_set = &led_sysfs_blink_set;
-		if (led_supported == TPACPI_LED_570)
-			tpacpi_leds[i].led_classdev.brightness_get =
-							&led_sysfs_get;
-
-		tpacpi_leds[i].led_classdev.name = tpacpi_led_names[i];
-
-		INIT_WORK(&tpacpi_leds[i].work, led_set_status_worker);
-
-		rc = led_classdev_register(&tpacpi_pdev->dev,
-					   &tpacpi_leds[i].led_classdev);
-		if (rc < 0) {
-			tpacpi_leds[i].led_classdev.name = NULL;
-			led_exit();
-			return rc;
+		if (!tpacpi_is_led_restricted(i)) {
+			rc = tpacpi_init_led(i);
+			if (rc < 0) {
+				led_exit();
+				return rc;
+			}
 		}
 	}
 
+#ifdef CONFIG_THINKPAD_ACPI_UNSAFE_LEDS
+	if (led_supported != TPACPI_LED_NONE)
+		printk(TPACPI_NOTICE
+			"warning: userspace override of important "
+			"firmware LEDs is enabled\n");
+#endif
 	return (led_supported != TPACPI_LED_NONE)? 0 : 1;
 }