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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=A/8AVUJdvOiynNLDMUmFl6p6jEKrS4pLsMpfZjizUzo=; b=XwCS+M3InNsrf7miZ2mu2JrjQg6L/+zWSVqCkKsl5OmL5qKbYO5EQP3ilnoqQ9z6wA Wbuc9s0WkWceXVGVAN/1cA7OdEoI2rC6/ZdYgdycao6y+1TkXFN2O6KcrjTV7XR/rHNB 0TTaPmibR6BhBeQnqhLHGXggBtFOz3ODBuXxL8n43JKw5b5hrOgBXCloTD/Joe8JxJ0X Vl4Wa47EB3cs99kBKDSh0TgXTadC32YBkGzY50Z6xLWfopo99qBSBstly0ZK1Dp7W551 yVww5aXVTIn7rHuWy5WQQrxFiqdrHrcmSC14Q6x6Tsv9yD62tv5jwtso0q1xbqVyym/s 8zRA== X-Gm-Message-State: AOAM533W7H0pzpxuzUnvgDkuGiGuF9u6IANbrnIgqKhQitS02x0JTf4+ 8iMNVMIaiDjfos8v8RQjwhI+uzAUGbiBYutRdTQ= X-Google-Smtp-Source: ABdhPJzYg1wP5drwVOQXE/AqhepEFdY0IS9y17Jl1ma8d1oEIchfTEfggGDsztl/Yq0qVt+/oxT0++TDbK1cOrN36ao= X-Received: by 2002:a63:545a:: with SMTP id e26mr7770326pgm.4.1590752117594; Fri, 29 May 2020 04:35:17 -0700 (PDT) MIME-Version: 1.0 References: <89f6393934fc6d493f8b9e87c1a6e916642b6a18.1590749143.git.cristian.ciocaltea@gmail.com> In-Reply-To: <89f6393934fc6d493f8b9e87c1a6e916642b6a18.1590749143.git.cristian.ciocaltea@gmail.com> From: Andy Shevchenko Date: Fri, 29 May 2020 14:35:05 +0300 Message-ID: Subject: Re: [PATCH 1/1] tty: serial: owl: Initialize lock before registering port To: Cristian Ciocaltea Cc: =?UTF-8?Q?Andreas_F=C3=A4rber?= , Manivannan Sadhasivam , Greg Kroah-Hartman , Jiri Slaby , Andy Shevchenko , "open list:SERIAL DRIVERS" , linux-arm Mailing List , Linux Kernel Mailing List , linux-actions@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Fri, May 29, 2020 at 2:09 PM Cristian Ciocaltea wrote: > > Running a lockdep-enabled kernel leads to the following splat when > probing the owl-uart driver: > > [ 1.271784] b0124000.serial: ttyOWL2 at MMIO 0xb0124000 (irq = 22, base_baud = 1500000) is a owl-uart > [ 1.281226] INFO: trying to register non-static key. > [ 1.286179] the code is fine but needs lockdep annotation. > [ 1.291648] turning off the locking correctness validator. > [ 1.297125] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc7+ #70 > [ 1.303462] Hardware name: Generic DT based system > [ 1.308268] [<80111d3c>] (unwind_backtrace) from [<8010c9b8>] (show_stack+0x10/0x14) > [ 1.316003] [<8010c9b8>] (show_stack) from [<805016b4>] (dump_stack+0xb4/0xe0) > [ 1.323218] [<805016b4>] (dump_stack) from [<80182dec>] (register_lock_class+0x25c/0x8f4) > [ 1.331391] [<80182dec>] (register_lock_class) from [<8017ee34>] (__lock_acquire+0xb4/0x2ee4) > [ 1.339901] [<8017ee34>] (__lock_acquire) from [<8018291c>] (lock_acquire+0x424/0x4c8) > [ 1.347813] [<8018291c>] (lock_acquire) from [<808597b0>] (_raw_spin_lock_irqsave+0x54/0x68) > [ 1.356242] [<808597b0>] (_raw_spin_lock_irqsave) from [<80582e94>] (uart_add_one_port+0x384/0x510) > [ 1.365276] [<80582e94>] (uart_add_one_port) from [<8058b4d0>] (owl_uart_probe+0x1bc/0x248) > [ 1.373621] [<8058b4d0>] (owl_uart_probe) from [<8059c0e4>] (platform_drv_probe+0x48/0x94) > [ 1.381874] [<8059c0e4>] (platform_drv_probe) from [<805997c4>] (really_probe+0x200/0x470) > [ 1.390123] [<805997c4>] (really_probe) from [<80599c80>] (driver_probe_device+0x16c/0x1bc) > [ 1.398461] [<80599c80>] (driver_probe_device) from [<80599f18>] (device_driver_attach+0x44/0x60) > [ 1.407317] [<80599f18>] (device_driver_attach) from [<8059a078>] (__driver_attach+0x144/0x14c) > [ 1.416000] [<8059a078>] (__driver_attach) from [<805978ac>] (bus_for_each_dev+0x5c/0xb4) > [ 1.424162] [<805978ac>] (bus_for_each_dev) from [<8059896c>] (bus_add_driver+0x118/0x204) > [ 1.432410] [<8059896c>] (bus_add_driver) from [<8059ae6c>] (driver_register+0xbc/0xf8) > [ 1.440405] [<8059ae6c>] (driver_register) from [<80c1fd24>] (owl_uart_init+0x20/0x40) > [ 1.448313] [<80c1fd24>] (owl_uart_init) from [<801021d8>] (do_one_initcall+0x184/0x3a4) > [ 1.456399] [<801021d8>] (do_one_initcall) from [<80c01100>] (kernel_init_freeable+0x264/0x2e4) > [ 1.465085] [<80c01100>] (kernel_init_freeable) from [<80850a88>] (kernel_init+0x8/0x110) > [ 1.473249] [<80850a88>] (kernel_init) from [<80100114>] (ret_from_fork+0x14/0x20) > [ 1.480800] Exception stack(0xee8bdfb0 to 0xee8bdff8) > [ 1.485841] dfa0: 00000000 00000000 00000000 00000000 > [ 1.494002] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > [ 1.502162] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000 > [ 1.508914] printk: console [ttyOWL2] enabled > > The locking issue occurs in uart_configure_port() when trying to > guard the call to set_mctrl(). > > uart_add_one_port() should normally initialize the spinlock via > uart_port_spin_lock_init(), but it never happens because the port is > detected as a console and, as a consequence, the spinlock is expected > to be already initialized. > > The commit a3cb39d258ef > ("serial: core: Allow detach and attach serial device for console") > changed the lock initialization logic to assume the spinlock is > initialized even if the console is not enabled. > > Therefore, initialize the lock explicitly in owl_uart_probe(), before > attempting to invoke uart_add_one_port(). Reviewed-by: Andy Shevchenko You are faster than me, thanks! > Fixes: a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") > Signed-off-by: Cristian Ciocaltea > --- > drivers/tty/serial/owl-uart.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/tty/serial/owl-uart.c b/drivers/tty/serial/owl-uart.c > index c149f8c30007..c2fa2f15d50a 100644 > --- a/drivers/tty/serial/owl-uart.c > +++ b/drivers/tty/serial/owl-uart.c > @@ -705,6 +705,8 @@ static int owl_uart_probe(struct platform_device *pdev) > owl_uart_ports[pdev->id] = owl_port; > platform_set_drvdata(pdev, owl_port); > > + spin_lock_init(&owl_port->port.lock); > + > ret = uart_add_one_port(&owl_uart_driver, &owl_port->port); > if (ret) > owl_uart_ports[pdev->id] = NULL; > -- > 2.26.2 > -- With Best Regards, Andy Shevchenko