From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 89D00485936; Wed, 23 Sep 2026 10:15:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790158548; cv=none; b=pZ+ENxf1KStKnBdUuhtBjkHhsuy4mEkhpSEyeOXxWEmOYiK7X9yenE0//K3M/4xymUby82d/qjgln/cIY1I8dizRWBsPtYJ0d/Xt2OD4HcBfLXCmpkX+QknHfhL7/0OGp9ClDkLZqx16PdSnKIu5NPhYNTGVY8wr6x37jGS3l9w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790158548; c=relaxed/simple; bh=IPqOfsGa0DArR4DFEj+yLFOa0Iyhls9HPZyVcFmiROo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=POp/9qmgSoRKwui1o83dcyUxGeL8BI0YSDZD8QMpv6EJzNXRMQzQCMD04wcM6X3nHBFKK6iawg8HSzfV49NxERdGcj4FZnCGYSJtPhM38FAg8tvEpxIgm4C13l4ZSaCHM21OvPQIjgSPPqZrGTeCMNMkzJX6/uP2HQvvRSE0MrE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1TUgeNDJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="1TUgeNDJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 579C51F000FF; Wed, 23 Sep 2026 10:15:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790158542; bh=cCkKiUkI5CBIxSOf3Rl7yoSbI+AcG0DMzQZmanndQ7Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=1TUgeNDJyGUoHMu/7rF9Ji1boADsBw1BJyz35sEUatTZhXYmj08V9bUcE1ybhn28W EdImQ5WA/1qzuUeX26KQCb/97MOuqzjtUCUVc1gddBnydJ1akeGHsEhBYWZM6uMsqb oshEVtAX94ty+yZr6i8IqJQpqD++YdebYHPlWl9g= Date: Wed, 23 Sep 2026 12:15:38 +0200 From: Greg Kroah-Hartman To: Myeonghun Pak Cc: Jiri Slaby , Neil Armstrong , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Dmitry Rokosov , linux-serial@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Ijae Kim Subject: Re: [PATCH] tty: serial: meson: fix UART driver lifetime Message-ID: <2026092344-unlawful-hurling-c87e@gregkh> References: <20260913034148.15068-1-mhun512@gmail.com> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260913034148.15068-1-mhun512@gmail.com> On Sat, Sep 12, 2026 at 11:41:48PM -0400, Myeonghun Pak wrote: > Moving Amlogic UART registration into probe left the first driver > registration behind if uart_add_one_port() failed. Adding the separate > ttyS driver later also exposed a global last-port test: removing the last > port of one driver kept it registered whenever the other had a port. > > Track whether probe registered the driver and undo it when port addition > fails. On remove, retain the current driver only if a remaining port maps > to that driver. Serialize the shared lifecycle decisions against parallel > probe and remove operations. > > This issue was identified during our ongoing static-analysis research while > reviewing kernel code. > > Fixes: bcb5645f99ef ("tty: serial: meson: redesign the module to platform_driver") > Fixes: e71aab9d6132 ("tty: serial: meson: apply ttyS devname instead of ttyAML for new SoCs") > Cc: stable@vger.kernel.org > Assisted-by: OpenAI:GPT-5.6 > Co-developed-by: Ijae Kim > Signed-off-by: Ijae Kim > Signed-off-by: Myeonghun Pak > --- > drivers/tty/serial/meson_uart.c | 52 +++++++++++++++++++++++++-------- > 1 file changed, 40 insertions(+), 12 deletions(-) > > diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c > index a6cb2a535..4bd9d9826 100644 > --- a/drivers/tty/serial/meson_uart.c > +++ b/drivers/tty/serial/meson_uart.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -80,6 +81,7 @@ static struct uart_driver meson_uart_driver_ttyAML; > static struct uart_driver meson_uart_driver_ttyS; > > static struct uart_port *meson_ports[AML_UART_PORT_NUM]; > +static DEFINE_MUTEX(meson_uart_mutex); > > struct meson_uart_data { > struct uart_driver *uart_driver; > @@ -692,6 +694,16 @@ static struct uart_driver *meson_uart_current(const struct meson_uart_data *pd) > pd->uart_driver : &meson_uart_driver_ttyAML; > } > > +static bool meson_uart_has_ports(struct uart_driver *uart_driver) As you require a lock to be held here, document it properly so the compiler will catch it when you get it wrong. > +{ > + for (int id = 0; id < AML_UART_PORT_NUM; id++) > + if (meson_ports[id] && > + meson_uart_current(meson_ports[id]->private_data) == uart_driver) > + return true; > + > + return false; > +} > + > static int meson_uart_probe(struct platform_device *pdev) > { > const struct meson_uart_data *priv_data; > @@ -702,6 +714,7 @@ static int meson_uart_probe(struct platform_device *pdev) > int ret = 0; > int irq; > bool has_rtscts; > + bool registered = false; > > if (pdev->dev.of_node) > pdev->id = of_alias_get_id(pdev->dev.of_node, "serial"); > @@ -731,11 +744,6 @@ static int meson_uart_probe(struct platform_device *pdev) > of_property_read_u32(pdev->dev.of_node, "fifo-size", &fifosize); > has_rtscts = of_property_read_bool(pdev->dev.of_node, "uart-has-rtscts"); > > - if (meson_ports[pdev->id]) { > - return dev_err_probe(&pdev->dev, -EBUSY, > - "port %d already allocated\n", pdev->id); > - } > - > port = devm_kzalloc(&pdev->dev, sizeof(struct uart_port), GFP_KERNEL); > if (!port) > return -ENOMEM; > @@ -748,11 +756,22 @@ static int meson_uart_probe(struct platform_device *pdev) > > uart_driver = meson_uart_current(priv_data); > > + mutex_lock(&meson_uart_mutex); guard? thanks, greg k-h