On Mon, Mar 18, 2019 at 05:49:06PM +0000, Marc Zyngier wrote:
> Running a kernel with the fusb302 driver and lockdep enabled
> leads to an unpleasant warning:
>
> [ 4.617477] INFO: trying to register non-static key.
> [ 4.617930] the code is fine but needs lockdep annotation.
> [ 4.618418] turning off the locking correctness validator.
> [ 4.618913] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.1.0-rc1-00007-g3542533f3fc9 #13
> [ 4.619620] Hardware name: rockchip evb_rk3399/evb_rk3399, BIOS 2019.04-rc3-00124-g2feec69fb1 03/15/2019
> [ 4.620454] Call trace:
> [ 4.620693] dump_backtrace+0x0/0x138
> [ 4.621028] show_stack+0x24/0x30
> [ 4.621336] dump_stack+0xbc/0x104
> [ 4.621649] register_lock_class+0x594/0x598
> [ 4.622036] __lock_acquire+0x80/0x11b8
> [ 4.622384] lock_acquire+0xdc/0x260
> [ 4.622711] __mutex_lock+0x90/0x8a0
> [ 4.623037] mutex_lock_nested+0x3c/0x50
> [ 4.623394] _fusb302_log+0x88/0x1f0
> [ 4.623721] fusb302_log+0x7c/0xa0
> [ 4.624033] tcpm_init+0x5c/0x190
> [ 4.624336] tcpm_init+0x3c/0x130
> [ 4.624640] tcpm_register_port+0x574/0x878
> [ 4.625019] fusb302_probe+0x2c8/0x590
>
> Despite what the message says, the code isn't fine, as it tries to
> make use of the fusb302_log facility pretty early. This requires the
> logbuffer_lock mutex to be initialised, but that only happens much
> later. Boo.
>
> Hoist the fusb302_debugfs_init call before tcpm_register_port so that
> we can enjoy a working mutex. At Guenter's request, also add teardown
> of the debugfs facility on the error path.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> drivers/usb/typec/tcpm/fusb302.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index e9344997329c..76cb8be6f3eb 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -1790,12 +1790,13 @@ static int fusb302_probe(struct i2c_client *client,
> goto destroy_workqueue;
> }
>
> + fusb302_debugfs_init(chip);
> chip->tcpm_port = tcpm_register_port(&client->dev, &chip->tcpc_dev);
> if (IS_ERR(chip->tcpm_port)) {
> ret = PTR_ERR(chip->tcpm_port);
> if (ret != -EPROBE_DEFER)
> dev_err(dev, "cannot register tcpm port, ret=%d", ret);
> - goto destroy_workqueue;
> + goto unregister_debugfs;
> }
>
> ret = devm_request_threaded_irq(chip->dev, chip->gpio_int_n_irq,
> @@ -1807,13 +1808,14 @@ static int fusb302_probe(struct i2c_client *client,
> goto tcpm_unregister_port;
> }
> enable_irq_wake(chip->gpio_int_n_irq);
> - fusb302_debugfs_init(chip);
> i2c_set_clientdata(client, chip);
>
> return ret;
>
> tcpm_unregister_port:
> tcpm_unregister_port(chip->tcpm_port);
> +unregister_debugfs:
> + fusb302_debugfs_exit(chip);
> destroy_workqueue:
> destroy_workqueue(chip->wq);
>
> --
> 2.20.1
>
