diff mbox series

usb: typec: fusb302: Fix debugfs mutex initialisation

Message ID 20190318150600.23417-1-marc.zyngier@arm.com (mailing list archive)
State Superseded
Headers show
Series usb: typec: fusb302: Fix debugfs mutex initialisation | expand

Commit Message

Marc Zyngier March 18, 2019, 3:06 p.m. UTC
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.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 drivers/usb/typec/tcpm/fusb302.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Guenter Roeck March 18, 2019, 3:39 p.m. UTC | #1
On Mon, Mar 18, 2019 at 03:06:00PM +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.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  drivers/usb/typec/tcpm/fusb302.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index e9344997329c..7e3f8901daf6 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -1790,6 +1790,7 @@ static int fusb302_probe(struct i2c_client *client,
>  			goto destroy_workqueue;
>  	}
>  
> +	fusb302_debugfs_init(chip);

This needs another error exit label right after destroy_workqueue,
and an added call to fusb302_debugfs_exit() after that label.

>  	chip->tcpm_port = tcpm_register_port(&client->dev, &chip->tcpc_dev);
>  	if (IS_ERR(chip->tcpm_port)) {
>  		ret = PTR_ERR(chip->tcpm_port);
> @@ -1807,7 +1808,6 @@ 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;
> -- 
> 2.20.1
>
Marc Zyngier March 18, 2019, 5:32 p.m. UTC | #2
On Mon, 18 Mar 2019 08:39:22 -0700
Guenter Roeck <linux@roeck-us.net> wrote:

> On Mon, Mar 18, 2019 at 03:06:00PM +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.
> > 
> > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> > ---
> >  drivers/usb/typec/tcpm/fusb302.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> > index e9344997329c..7e3f8901daf6 100644
> > --- a/drivers/usb/typec/tcpm/fusb302.c
> > +++ b/drivers/usb/typec/tcpm/fusb302.c
> > @@ -1790,6 +1790,7 @@ static int fusb302_probe(struct i2c_client *client,
> >  			goto destroy_workqueue;
> >  	}
> >  
> > +	fusb302_debugfs_init(chip);  
> 
> This needs another error exit label right after destroy_workqueue,
> and an added call to fusb302_debugfs_exit() after that label.

You do mean before destroy_workqueue, right? Otherwise, the error
handling doesn't nest properly... Something like this:

diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
index 7e3f8901daf6..76cb8be6f3eb 100644
--- a/drivers/usb/typec/tcpm/fusb302.c
+++ b/drivers/usb/typec/tcpm/fusb302.c
@@ -1796,7 +1796,7 @@ static int fusb302_probe(struct i2c_client *client,
 		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,
@@ -1814,6 +1814,8 @@ static int fusb302_probe(struct i2c_client *client,
 
 tcpm_unregister_port:
 	tcpm_unregister_port(chip->tcpm_port);
+unregister_debugfs:
+	fusb302_debugfs_exit(chip);
 destroy_workqueue:
 	destroy_workqueue(chip->wq);
 
Thanks,

	M.
Guenter Roeck March 18, 2019, 5:40 p.m. UTC | #3
On Mon, Mar 18, 2019 at 05:32:56PM +0000, Marc Zyngier wrote:
> On Mon, 18 Mar 2019 08:39:22 -0700
> Guenter Roeck <linux@roeck-us.net> wrote:
> 
> > On Mon, Mar 18, 2019 at 03:06:00PM +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.
> > > 
> > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> > > ---
> > >  drivers/usb/typec/tcpm/fusb302.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> > > index e9344997329c..7e3f8901daf6 100644
> > > --- a/drivers/usb/typec/tcpm/fusb302.c
> > > +++ b/drivers/usb/typec/tcpm/fusb302.c
> > > @@ -1790,6 +1790,7 @@ static int fusb302_probe(struct i2c_client *client,
> > >  			goto destroy_workqueue;
> > >  	}
> > >  
> > > +	fusb302_debugfs_init(chip);  
> > 
> > This needs another error exit label right after destroy_workqueue,
> > and an added call to fusb302_debugfs_exit() after that label.
> 
> You do mean before destroy_workqueue, right? Otherwise, the error
> handling doesn't nest properly... Something like this:
> 
Yes, you are correct. Sorry for the confusion.

Guenter

> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index 7e3f8901daf6..76cb8be6f3eb 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -1796,7 +1796,7 @@ static int fusb302_probe(struct i2c_client *client,
>  		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,
> @@ -1814,6 +1814,8 @@ static int fusb302_probe(struct i2c_client *client,
>  
>  tcpm_unregister_port:
>  	tcpm_unregister_port(chip->tcpm_port);
> +unregister_debugfs:
> +	fusb302_debugfs_exit(chip);
>  destroy_workqueue:
>  	destroy_workqueue(chip->wq);
>  
> Thanks,
> 
> 	M.
> -- 
> Without deviation from the norm, progress is not possible.
diff mbox series

Patch

diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
index e9344997329c..7e3f8901daf6 100644
--- a/drivers/usb/typec/tcpm/fusb302.c
+++ b/drivers/usb/typec/tcpm/fusb302.c
@@ -1790,6 +1790,7 @@  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);
@@ -1807,7 +1808,6 @@  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;