Hi,
I work on an omap platform running linux 3.0.21. The kernel image embeds two
built-in i2c drivers for two different proximity sensors.
The hardware platform embeds only one sensor, so there is a detection mechanism
of which chip is present in each driver (code below).
I recently changed the sensor on my board. Leading to kernel crash when
entering suspend.
Thanks to "no_console_suspend" cmdline argument, I found out that the suspend
function of the "absent" chip gets called. It tries to take a mutex which has
been freed in probe's "device not found" fallback code. Leading to kernel panic.
I naively tried to add "i2c_del_driver(&vcnl4010_driver);" in the driver's
probe function.
But it triggers a null ptr deref in i2c_do_del_adapter().
How can I gracefully unload this i2c driver if chip is not detected, while
keeping this driver built-in in the kernel?
What is the recommended method to do just that?
Thanks,
Emeric
---------
static struct i2c_driver vcnl4010_driver;
static int __devinit vcnl4010_driver_probe(struct i2c_client *client, const
struct i2c_device_id *id)
{
[...]
if(vcnl4010_read_transfer(data, VCNL4010_PROD_ID_VER, ®_val, 1) !=0 )
{
pr_err("vcnl4010: Device not found!");
goto nochip;
}
if(reg_val != 0x21)
{
pr_err("vcnl4010: Found device isn't a vcnl4010, is a vcnl4000
installed?");
goto badchip;
}
[...]
badchip:
nochip:
input_unregister_device(data->input_dev);
dev_register_error:
input_free_device(data->input_dev);
dev_allocate_error:
mutex_destroy(&data->lock);
kfree(data);
error:
/* i2c_del_driver(&vcnl4010_driver); triggers NULL ptr deref in
i2c_do_del_adapter() */
return ret;
}
static int vcnl4010_driver_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct vcnl4010_data *data = platform_get_drvdata(pdev);
mutex_lock(&data->lock); /* panic kernel if chip is not present */
vcnl4010_write(data, VCNL4010_CMD_REG, 0x00);
vcnl4010_write(data, VCNL4010_IR_LED_CURR, 0);
mutex_unlock(&data->lock);
return 0;
}
static struct i2c_driver vcnl4010_driver = {
.probe = vcnl4010_driver_probe,
.remove = vcnl4010_driver_remove,
.id_table = vcnl4010_idtable,
.driver = {
.name = DRIVER_NAME,
#ifdef CONFIG_PM
.pm = &vcnl4010_pm_ops,
#endif
},
};
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