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Mon, 18 Mar 2019 11:18:43 -0700 (PDT) Date: Mon, 18 Mar 2019 11:18:41 -0700 From: Guenter Roeck To: Marc Zyngier Cc: Heikki Krogerus , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] usb: typec: fusb302: Fix debugfs mutex initialisation Message-ID: <20190318181841.GA25132@roeck-us.net> References: <20190318174906.10429-1-marc.zyngier@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190318174906.10429-1-marc.zyngier@arm.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Reviewed-by: Guenter Roeck > --- > 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 >