Sorry. My mistake. In this case it seems that sleep functions can
be called from apds990x_irq, since interrupt line is disabled globally
(because of IRQF_ONESHOT). And nothing bad will happen if
you know that device can be blocked for relatively long time.

2012/7/31 Denis Yefremov [off-list ref]:

Interrupt handler apds990x_irq in APDS990x sensor driver
invokes mutex_lock  that is might sleep operation.

Found by Linux Driver Verification project (linuxtesting.org)
within my participation in the GSoC 2012 program.


static irqreturn_t apds990x_irq(int irq, void *data)
{
        struct apds990x_chip *chip = data;
        u8 status;

        apds990x_read_byte(chip, APDS990X_STATUS, &status);
        apds990x_ack_int(chip, status);

        mutex_lock(&chip->mutex);
...
}

static int __devinit apds990x_probe(struct i2c_client *client,
                                const struct i2c_device_id *id)
{
...
        err = request_threaded_irq(client->irq, NULL,
                                apds990x_irq,
                                IRQF_TRIGGER_FALLING | IRQF_TRIGGER_LOW |
                                IRQF_ONESHOT,
                                "apds990x", chip);
...
}