HID: cp2112: fix sleep-while-atomic

A recent commit fixing DMA-buffers on stack added a shared transfer
buffer protected by a spinlock. This is broken as the USB HID request
callbacks can sleep. Fix this up by replacing the spinlock with a mutex.

Fixes: 1ffb3c40ffb5 ("HID: cp2112: make transfer buffers DMA capable")
Cc: stable <stable@vger.kernel.org>	# 4.9
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index f31a778..3e0b6ba 100644 (file)
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -168,7 +168,7 @@ struct cp2112_device {
        atomic_t xfer_avail;
        struct gpio_chip gc;
        u8 *in_out_buffer;
-       spinlock_t lock;
+       struct mutex lock;
 
        struct gpio_desc *desc[8];
        bool gpio_poll;
@@ -186,10 +186,9 @@ static int cp2112_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
        struct cp2112_device *dev = gpiochip_get_data(chip);
        struct hid_device *hdev = dev->hdev;
        u8 *buf = dev->in_out_buffer;
-       unsigned long flags;
        int ret;
 
-       spin_lock_irqsave(&dev->lock, flags);
+       mutex_lock(&dev->lock);
 
        ret = hid_hw_raw_request(hdev, CP2112_GPIO_CONFIG, buf,
                                 CP2112_GPIO_CONFIG_LENGTH, HID_FEATURE_REPORT,
@@ -213,7 +212,7 @@ static int cp2112_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
        ret = 0;
 
 exit:
-       spin_unlock_irqrestore(&dev->lock, flags);
+       mutex_unlock(&dev->lock);
        return ret <= 0 ? ret : -EIO;
 }
 
@@ -222,10 +221,9 @@ static void cp2112_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
        struct cp2112_device *dev = gpiochip_get_data(chip);
        struct hid_device *hdev = dev->hdev;
        u8 *buf = dev->in_out_buffer;
-       unsigned long flags;
        int ret;
 
-       spin_lock_irqsave(&dev->lock, flags);
+       mutex_lock(&dev->lock);
 
        buf[0] = CP2112_GPIO_SET;
        buf[1] = value ? 0xff : 0;
@@ -237,7 +235,7 @@ static void cp2112_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
        if (ret < 0)
                hid_err(hdev, "error setting GPIO values: %d\n", ret);
 
-       spin_unlock_irqrestore(&dev->lock, flags);
+       mutex_unlock(&dev->lock);
 }
 
 static int cp2112_gpio_get_all(struct gpio_chip *chip)
@@ -245,10 +243,9 @@ static int cp2112_gpio_get_all(struct gpio_chip *chip)
        struct cp2112_device *dev = gpiochip_get_data(chip);
        struct hid_device *hdev = dev->hdev;
        u8 *buf = dev->in_out_buffer;
-       unsigned long flags;
        int ret;
 
-       spin_lock_irqsave(&dev->lock, flags);
+       mutex_lock(&dev->lock);
 
        ret = hid_hw_raw_request(hdev, CP2112_GPIO_GET, buf,
                                 CP2112_GPIO_GET_LENGTH, HID_FEATURE_REPORT,
@@ -262,7 +259,7 @@ static int cp2112_gpio_get_all(struct gpio_chip *chip)
        ret = buf[1];
 
 exit:
-       spin_unlock_irqrestore(&dev->lock, flags);
+       mutex_unlock(&dev->lock);
 
        return ret;
 }
@@ -284,10 +281,9 @@ static int cp2112_gpio_direction_output(struct gpio_chip *chip,
        struct cp2112_device *dev = gpiochip_get_data(chip);
        struct hid_device *hdev = dev->hdev;
        u8 *buf = dev->in_out_buffer;
-       unsigned long flags;
        int ret;
 
-       spin_lock_irqsave(&dev->lock, flags);
+       mutex_lock(&dev->lock);
 
        ret = hid_hw_raw_request(hdev, CP2112_GPIO_CONFIG, buf,
                                 CP2112_GPIO_CONFIG_LENGTH, HID_FEATURE_REPORT,
@@ -308,7 +304,7 @@ static int cp2112_gpio_direction_output(struct gpio_chip *chip,
                goto fail;
        }
 
-       spin_unlock_irqrestore(&dev->lock, flags);
+       mutex_unlock(&dev->lock);
 
        /*
         * Set gpio value when output direction is already set,
@@ -319,7 +315,7 @@ static int cp2112_gpio_direction_output(struct gpio_chip *chip,
        return 0;
 
 fail:
-       spin_unlock_irqrestore(&dev->lock, flags);
+       mutex_unlock(&dev->lock);
        return ret < 0 ? ret : -EIO;
 }
 
@@ -1235,7 +1231,7 @@ static int cp2112_probe(struct hid_device *hdev, const struct hid_device_id *id)
        if (!dev->in_out_buffer)
                return -ENOMEM;
 
-       spin_lock_init(&dev->lock);
+       mutex_init(&dev->lock);
 
        ret = hid_parse(hdev);
        if (ret) {