[PATCH v2 10/15] HID: hid-lg4ff: Protect concurrent access to output HID report with a spinlock

["Michal Malý" <madcatxster@devoid-pointer.net>]

Protect concurrent access to output HID report with a spinlock. The HID report
structure used to submit commands to wheels is shared amongst all functions that
need to do so and some of these functions can be executed in parallel.
Additionally, lg4ff_play() can be called from interrupt context by ff-memless
module. Locking is necessary to prevent sending bogus data to the wheels.

Signed-off-by: Michal Malý <madcatxster@devoid-pointer.net>
---
 drivers/hid/hid-lg4ff.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

diff --git a/drivers/hid/hid-lg4ff.c b/drivers/hid/hid-lg4ff.c
index 031b8ab..f7f4eb6 100644
--- a/drivers/hid/hid-lg4ff.c
+++ b/drivers/hid/hid-lg4ff.c
@@ -89,6 +89,7 @@ struct lg4ff_wheel_data {
 };
 
 struct lg4ff_device_entry {
+	spinlock_t report_lock; /* Protect output HID report */
 	struct lg4ff_wheel_data wdata;
 };
 
@@ -303,9 +304,24 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec
 	struct hid_device *hid = input_get_drvdata(dev);
 	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	struct lg4ff_device_entry *entry;
+	struct lg_drv_data *drv_data;
+	unsigned long flags;
 	s32 *value = report->field[0]->value;
 	int x;
 
+	drv_data = hid_get_drvdata(hid);
+	if (!drv_data) {
+		hid_err(hid, "Private driver data not found!\n");
+		return -EINVAL;
+	}
+
+	entry = drv_data->device_props;
+	if (!entry) {
+		hid_err(hid, "Device properties not found!\n");
+		return -EINVAL;
+	}
+
 #define CLAMP(x) do { if (x < 0) x = 0; else if (x > 0xff) x = 0xff; } while (0)
 
 	switch (effect->type) {
@@ -313,6 +329,7 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec
 		x = effect->u.ramp.start_level + 0x80;	/* 0x80 is no force */
 		CLAMP(x);
 
+		spin_lock_irqsave(&entry->report_lock, flags);
 		if (x == 0x80) {
 			/* De-activate force in slot-1*/
 			value[0] = 0x13;
@@ -324,6 +341,7 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec
 			value[6] = 0x00;
 
 			hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+			spin_unlock_irqrestore(&entry->report_lock, flags);
 			return 0;
 		}
 
@@ -336,6 +354,7 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec
 		value[6] = 0x00;
 
 		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		spin_unlock_irqrestore(&entry->report_lock, flags);
 		break;
 	}
 	return 0;
@@ -352,6 +371,7 @@ static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
 	u32 expand_a, expand_b;
 	struct lg4ff_device_entry *entry;
 	struct lg_drv_data *drv_data;
+	unsigned long flags;
 
 	drv_data = hid_get_drvdata(hid);
 	if (!drv_data) {
@@ -366,6 +386,7 @@ static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
 	}
 
 	/* De-activate Auto-Center */
+	spin_lock_irqsave(&entry->report_lock, flags);
 	if (magnitude == 0) {
 		value[0] = 0xf5;
 		value[1] = 0x00;
@@ -376,6 +397,7 @@ static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
 		value[6] = 0x00;
 
 		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		spin_unlock_irqrestore(&entry->report_lock, flags);
 		return;
 	}
 
@@ -417,6 +439,7 @@ static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude)
 	value[6] = 0x00;
 
 	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+	spin_unlock_irqrestore(&entry->report_lock, flags);
 }
 
 /* Sends autocentering command compatible with Formula Force EX */
@@ -425,9 +448,25 @@ static void lg4ff_set_autocenter_ffex(struct input_dev *dev, u16 magnitude)
 	struct hid_device *hid = input_get_drvdata(dev);
 	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	struct lg4ff_device_entry *entry;
+	struct lg_drv_data *drv_data;
+	unsigned long flags;
 	s32 *value = report->field[0]->value;
 	magnitude = magnitude * 90 / 65535;
 
+	drv_data = hid_get_drvdata(hid);
+	if (!drv_data) {
+		hid_err(hid, "Private driver data not found!\n");
+		return;
+	}
+
+	entry = drv_data->device_props;
+	if (!entry) {
+		hid_err(hid, "Device properties not found!\n");
+		return;
+	}
+
+	spin_lock_irqsave(&entry->report_lock, flags);
 	value[0] = 0xfe;
 	value[1] = 0x03;
 	value[2] = magnitude >> 14;
@@ -437,6 +476,7 @@ static void lg4ff_set_autocenter_ffex(struct input_dev *dev, u16 magnitude)
 	value[6] = 0x00;
 
 	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+	spin_unlock_irqrestore(&entry->report_lock, flags);
 }
 
 /* Sends command to set range compatible with G25/G27/Driving Force GT */
@@ -444,10 +484,26 @@ static void lg4ff_set_range_g25(struct hid_device *hid, u16 range)
 {
 	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	struct lg4ff_device_entry *entry;
+	struct lg_drv_data *drv_data;
+	unsigned long flags;
 	s32 *value = report->field[0]->value;
 
+	drv_data = hid_get_drvdata(hid);
+	if (!drv_data) {
+		hid_err(hid, "Private driver data not found!\n");
+		return;
+	}
+
+	entry = drv_data->device_props;
+	if (!entry) {
+		hid_err(hid, "Device properties not found!\n");
+		return;
+	}
+
 	dbg_hid("G25/G27/DFGT: setting range to %u\n", range);
 
+	spin_lock_irqsave(&entry->report_lock, flags);
 	value[0] = 0xf8;
 	value[1] = 0x81;
 	value[2] = range & 0x00ff;
@@ -457,6 +513,7 @@ static void lg4ff_set_range_g25(struct hid_device *hid, u16 range)
 	value[6] = 0x00;
 
 	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+	spin_unlock_irqrestore(&entry->report_lock, flags);
 }
 
 /* Sends commands to set range compatible with Driving Force Pro wheel */
@@ -465,11 +522,27 @@ static void lg4ff_set_range_dfp(struct hid_device *hid, u16 range)
 	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
 	int start_left, start_right, full_range;
+	struct lg4ff_device_entry *entry;
+	struct lg_drv_data *drv_data;
+	unsigned long flags;
 	s32 *value = report->field[0]->value;
 
+	drv_data = hid_get_drvdata(hid);
+	if (!drv_data) {
+		hid_err(hid, "Private driver data not found!\n");
+		return;
+	}
+
+	entry = drv_data->device_props;
+	if (!entry) {
+		hid_err(hid, "Device properties not found!\n");
+		return;
+	}
+
 	dbg_hid("Driving Force Pro: setting range to %u\n", range);
 
 	/* Prepare "coarse" limit command */
+	spin_lock_irqsave(&entry->report_lock, flags);
 	value[0] = 0xf8;
 	value[1] = 0x00;	/* Set later */
 	value[2] = 0x00;
@@ -498,6 +571,7 @@ static void lg4ff_set_range_dfp(struct hid_device *hid, u16 range)
 
 	if (range == 200 || range == 900) {	/* Do not apply any fine limit */
 		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		spin_unlock_irqrestore(&entry->report_lock, flags);
 		return;
 	}
 
@@ -512,6 +586,7 @@ static void lg4ff_set_range_dfp(struct hid_device *hid, u16 range)
 	value[6] = 0xff;
 
 	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+	spin_unlock_irqrestore(&entry->report_lock, flags);
 }
 
 static const struct lg4ff_compat_mode_switch *lg4ff_get_mode_switch_command(const u16 real_product_id, const u16 target_product_id)
@@ -575,9 +650,25 @@ static int lg4ff_switch_compatibility_mode(struct hid_device *hid, const struct
 {
 	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	struct lg4ff_device_entry *entry;
+	struct lg_drv_data *drv_data;
+	unsigned long flags;
 	s32 *value = report->field[0]->value;
 	u8 i;
 
+	drv_data = hid_get_drvdata(hid);
+	if (!drv_data) {
+		hid_err(hid, "Private driver data not found!\n");
+		return -EINVAL;
+	}
+
+	entry = drv_data->device_props;
+	if (!entry) {
+		hid_err(hid, "Device properties not found!\n");
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&entry->report_lock, flags);
 	for (i = 0; i < s->cmd_count; i++) {
 		u8 j;
 
@@ -586,6 +677,7 @@ static int lg4ff_switch_compatibility_mode(struct hid_device *hid, const struct
 
 		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
 	}
+	spin_unlock_irqrestore(&entry->report_lock, flags);
 	hid_hw_wait(hid);
 	return 0;
 }
@@ -826,8 +918,24 @@ static void lg4ff_set_leds(struct hid_device *hid, u8 leds)
 {
 	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
 	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	struct lg_drv_data *drv_data;
+	struct lg4ff_device_entry *entry;
+	unsigned long flags;
 	s32 *value = report->field[0]->value;
 
+	drv_data = hid_get_drvdata(hid);
+	if (!drv_data) {
+		hid_err(hid, "Private driver data not found!\n");
+		return;
+	}
+
+	entry = drv_data->device_props;
+	if (!entry) {
+		hid_err(hid, "Device properties not found!\n");
+		return;
+	}
+
+	spin_lock_irqsave(&entry->report_lock, flags);
 	value[0] = 0xf8;
 	value[1] = 0x12;
 	value[2] = leds;
@@ -836,6 +944,7 @@ static void lg4ff_set_leds(struct hid_device *hid, u8 leds)
 	value[5] = 0x00;
 	value[6] = 0x00;
 	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+	spin_unlock_irqrestore(&entry->report_lock, flags);
 }
 
 static void lg4ff_led_set_brightness(struct led_classdev *led_cdev,
@@ -1015,6 +1124,7 @@ int lg4ff_init(struct hid_device *hid)
 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry)
 		return -ENOMEM;
+	spin_lock_init(&entry->report_lock);
 	drv_data->device_props = entry;
 
 	/* Check if a multimode wheel has been connected and
-- 
2.3.5

--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html