ACPI: thinkpad-acpi: protect fan and hotkey data structures

Add proper mutex locking to some data structures access subject to races
due to concurrent access of driver functions on the hotkey and fan
subdrivers.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/misc/thinkpad_acpi.c

@@ -704,6 +704,7 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
 	vdbg_printk(TPACPI_DBG_INIT, "initializing hotkey subdriver\n");
 
 	IBM_ACPIHANDLE_INIT(hkey);
+	mutex_init(&hotkey_mutex);
 
 	/* hotkey not supported on 570 */
 	tp_features.hotkey = hkey_handle != NULL;
@@ -752,6 +753,9 @@ static void hotkey_notify(struct ibm_struct *ibm, u32 event)
 	}
 }
 
+/*
+ * Call with hotkey_mutex held
+ */
 static int hotkey_get(int *status, int *mask)
 {
 	if (!acpi_evalf(hkey_handle, status, "DHKC", "d"))
@@ -764,6 +768,9 @@ static int hotkey_get(int *status, int *mask)
 	return 0;
 }
 
+/*
+ * Call with hotkey_mutex held
+ */
 static int hotkey_set(int status, int mask)
 {
 	int i;
@@ -792,7 +799,11 @@ static int hotkey_read(char *p)
 		return len;
 	}
 
+	res = mutex_lock_interruptible(&hotkey_mutex);
+	if (res < 0)
+		return res;
 	res = hotkey_get(&status, &mask);
+	mutex_unlock(&hotkey_mutex);
 	if (res)
 		return res;
 
@@ -818,10 +829,15 @@ static int hotkey_write(char *buf)
 	if (!tp_features.hotkey)
 		return -ENODEV;
 
+	res = mutex_lock_interruptible(&hotkey_mutex);
+	if (res < 0)
+		return res;
+
 	res = hotkey_get(&status, &mask);
 	if (res)
-		return res;
+		goto errexit;
 
+	res = 0;
 	while ((cmd = next_cmd(&buf))) {
 		if (strlencmp(cmd, "enable") == 0) {
 			status = 1;
@@ -834,18 +850,19 @@ static int hotkey_write(char *buf)
 			/* mask set */
 		} else if (sscanf(cmd, "%x", &mask) == 1) {
 			/* mask set */
-		} else
-			return -EINVAL;
+		} else {
+			res = -EINVAL;
+			goto errexit;
+		}
 		do_cmd = 1;
 	}
 
-	if (do_cmd) {
+	if (do_cmd)
 		res = hotkey_set(status, mask);
-		if (res)
-			return res;
-	}
 
-	return 0;
+errexit:
+	mutex_unlock(&hotkey_mutex);
+	return res;
 }
 
 static struct tp_acpi_drv_struct ibm_hotkey_acpidriver = {
@@ -2575,6 +2592,7 @@ static int __init fan_init(struct ibm_init_struct *iibm)
 {
 	vdbg_printk(TPACPI_DBG_INIT, "initializing fan subdriver\n");
 
+	mutex_init(&fan_mutex);
 	fan_status_access_mode = TPACPI_FAN_NONE;
 	fan_control_access_mode = TPACPI_FAN_WR_NONE;
 	fan_control_commands = 0;
@@ -2764,10 +2782,17 @@ static void fan_watchdog_reset(void)
 
 static int fan_set_level(int level)
 {
+	int res;
+
 	switch (fan_control_access_mode) {
 	case TPACPI_FAN_WR_ACPI_SFAN:
 		if (level >= 0 && level <= 7) {
-			if (!acpi_evalf(sfan_handle, NULL, NULL, "vd", level))
+			res = mutex_lock_interruptible(&fan_mutex);
+			if (res < 0)
+				return res;
+			res = acpi_evalf(sfan_handle, NULL, NULL, "vd", level);
+			mutex_unlock(&fan_mutex);
+			if (!res)
 				return -EIO;
 		} else
 			return -EINVAL;
@@ -2780,7 +2805,12 @@ static int fan_set_level(int level)
 		    ((level < 0) || (level > 7)))
 			return -EINVAL;
 
-		if (!acpi_ec_write(fan_status_offset, level))
+		res = mutex_lock_interruptible(&fan_mutex);
+		if (res < 0)
+			return res;
+		res = acpi_ec_write(fan_status_offset, level);
+		mutex_unlock(&fan_mutex);
+		if (!res)
 			return -EIO;
 		else
 			tp_features.fan_ctrl_status_undef = 0;
@@ -2797,25 +2827,33 @@ static int fan_set_enable(void)
 	u8 s;
 	int rc;
 
+	rc = mutex_lock_interruptible(&fan_mutex);
+	if (rc < 0)
+		return rc;
+
 	switch (fan_control_access_mode) {
 	case TPACPI_FAN_WR_ACPI_FANS:
 	case TPACPI_FAN_WR_TPEC:
-		if ((rc = fan_get_status(&s)) < 0)
-			return rc;
+		rc = fan_get_status(&s);
+		if (rc < 0)
+			break;
 
 		/* Don't go out of emergency fan mode */
 		if (s != 7)
 			s = TP_EC_FAN_AUTO;
 
 		if (!acpi_ec_write(fan_status_offset, s))
-			return -EIO;
-		else
+			rc = -EIO;
+		else {
 			tp_features.fan_ctrl_status_undef = 0;
+			rc = 0;
+		}
 		break;
 
 	case TPACPI_FAN_WR_ACPI_SFAN:
-		if ((rc = fan_get_status(&s)) < 0)
-			return rc;
+		rc = fan_get_status(&s);
+		if (rc < 0)
+			break;
 
 		s &= 0x07;
 
@@ -2824,53 +2862,75 @@ static int fan_set_enable(void)
 			s = 4;
 
 		if (!acpi_evalf(sfan_handle, NULL, NULL, "vd", s))
-			return -EIO;
+			rc= -EIO;
+		else
+			rc = 0;
 		break;
 
 	default:
-		return -ENXIO;
+		rc = -ENXIO;
 	}
-	return 0;
+
+	mutex_unlock(&fan_mutex);
+	return rc;
 }
 
 static int fan_set_disable(void)
 {
+	int rc;
+
+	rc = mutex_lock_interruptible(&fan_mutex);
+	if (rc < 0)
+		return rc;
+
+	rc = 0;
 	switch (fan_control_access_mode) {
 	case TPACPI_FAN_WR_ACPI_FANS:
 	case TPACPI_FAN_WR_TPEC:
 		if (!acpi_ec_write(fan_status_offset, 0x00))
-			return -EIO;
+			rc = -EIO;
 		else
 			tp_features.fan_ctrl_status_undef = 0;
 		break;
 
 	case TPACPI_FAN_WR_ACPI_SFAN:
 		if (!acpi_evalf(sfan_handle, NULL, NULL, "vd", 0x00))
-			return -EIO;
+			rc = -EIO;
 		break;
 
 	default:
-		return -ENXIO;
+		rc = -ENXIO;
 	}
-	return 0;
+
+	mutex_unlock(&fan_mutex);
+	return rc;
 }
 
 static int fan_set_speed(int speed)
 {
+	int rc;
+
+	rc = mutex_lock_interruptible(&fan_mutex);
+	if (rc < 0)
+		return rc;
+
+	rc = 0;
 	switch (fan_control_access_mode) {
 	case TPACPI_FAN_WR_ACPI_FANS:
 		if (speed >= 0 && speed <= 65535) {
 			if (!acpi_evalf(fans_handle, NULL, NULL, "vddd",
 					speed, speed, speed))
-				return -EIO;
+				rc = -EIO;
 		} else
-			return -EINVAL;
+			rc = -EINVAL;
 		break;
 
 	default:
-		return -ENXIO;
+		rc = -ENXIO;
 	}
-	return 0;
+
+	mutex_unlock(&fan_mutex);
+	return rc;
 }
 
 static int fan_read(char *p)

drivers/misc/thinkpad_acpi.h

@@ -30,6 +30,7 @@
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/list.h>
+#include <linux/mutex.h>
 
 #include <linux/proc_fs.h>
 #include <linux/sysfs.h>
@@ -375,6 +376,8 @@ static enum fan_control_commands fan_control_commands;
 static u8 fan_control_initial_status;
 static int fan_watchdog_maxinterval;
 
+struct mutex fan_mutex;
+
 static acpi_handle fans_handle, gfan_handle, sfan_handle;
 
 static int fan_init(struct ibm_init_struct *iibm);
@@ -403,6 +406,8 @@ static int fan_write_cmd_watchdog(const char *cmd, int *rc);
 static int hotkey_orig_status;
 static int hotkey_orig_mask;
 
+static struct mutex hotkey_mutex;
+
 static int hotkey_init(struct ibm_init_struct *iibm);
 static void hotkey_exit(void);
 static int hotkey_get(int *status, int *mask);