[PATCH 1/2] HID: cp2112: fix sleep-while-atomic

Johan Hovold
2017-01-30T10:30:06Z

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>
---
drivers/hid/hid-cp2112.c | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index f31a778b0851..3e0b6bad29f2 100644
--- 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) {
--
2.10.2