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Tue, 05 Aug 2025 12:51:56 -0700 (PDT) From: Abinash Singh To: gregkh@linuxfoundation.org Cc: jirislaby@kernel.org, andriy.shevchenko@linux.intel.com, sunilvl@ventanamicro.com, arnd@arndb.de, u.kleine-koenig@baylibre.com, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, abinashsinghlalotra@gmail.com Subject: [RFC PATCH 2/2] tty: serial/8250: Fix build warning in serial8250_probe_platform() Date: Wed, 6 Aug 2025 01:21:55 +0530 Message-ID: <20250805195155.742004-2-abinashsinghlalotra@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250805195155.742004-1-abinashsinghlalotra@gmail.com> References: <20250805195155.742004-1-abinashsinghlalotra@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=UTF-8 Content-Transfer-Encoding: 8bit The function serial8250_probe_platform() in 8250_platform.c triggered a frame size warning: drivers/tty/serial/8250/8250_platform.c: In function ‘serial8250_probe_platform.isra’: drivers/tty/serial/8250/8250_platform.c:201:1: warning: the frame size of 1184 bytes is larger than 1024 bytes [-Wframe-larger-than=] This patch reduces the stack usage by dynamically allocating the `uart` structure using kmalloc(), rather than placing it on the stack. This eliminates the overflow warning and improves kernel robustness. Signed-off-by: Abinash Singh --- The stack usage was further confirmed by using -fstack-usage flag. it was usiing 1248 bytes: .............................. drivers/tty/serial/8250/8250_platform.c:154:12:serial8250_probe_platform.isra 1248 dynamic,bounded drivers/tty/serial/8250/8250_platform.c:208:12:serial8250_probe 16 static ...................................... After applying the patch it becomes : ......... It doesn't show up in stack usage and warning is fixed. ....... This function is used for probing . So dynamic allocation will not create any issues. Thank You --- drivers/tty/serial/8250/8250_platform.c | 63 +++++++++++++------------ 1 file changed, 33 insertions(+), 30 deletions(-) diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c index f7f9c5036d39..86816d9b32ce 100644 --- a/drivers/tty/serial/8250/8250_platform.c +++ b/drivers/tty/serial/8250/8250_platform.c @@ -158,43 +158,46 @@ static int serial8250_probe_acpi(struct platform_device *pdev) static int serial8250_probe_platform(struct platform_device *dev, struct plat_serial8250_port *p) { - struct uart_8250_port uart; + struct uart_8250_port *uart __free(kfree) = NULL; int ret, i, irqflag = 0; - memset(&uart, 0, sizeof(uart)); + uart = kmalloc(sizeof(*uart), GFP_KERNEL); + if (!uart) + return -ENOMEM; + memset(uart, 0, sizeof(*uart)); if (share_irqs) irqflag = IRQF_SHARED; for (i = 0; p && p->flags != 0; p++, i++) { - uart.port.iobase = p->iobase; - uart.port.membase = p->membase; - uart.port.irq = p->irq; - uart.port.irqflags = p->irqflags; - uart.port.uartclk = p->uartclk; - uart.port.regshift = p->regshift; - uart.port.iotype = p->iotype; - uart.port.flags = p->flags; - uart.port.mapbase = p->mapbase; - uart.port.mapsize = p->mapsize; - uart.port.hub6 = p->hub6; - uart.port.has_sysrq = p->has_sysrq; - uart.port.private_data = p->private_data; - uart.port.type = p->type; - uart.bugs = p->bugs; - uart.port.serial_in = p->serial_in; - uart.port.serial_out = p->serial_out; - uart.dl_read = p->dl_read; - uart.dl_write = p->dl_write; - uart.port.handle_irq = p->handle_irq; - uart.port.handle_break = p->handle_break; - uart.port.set_termios = p->set_termios; - uart.port.set_ldisc = p->set_ldisc; - uart.port.get_mctrl = p->get_mctrl; - uart.port.pm = p->pm; - uart.port.dev = &dev->dev; - uart.port.irqflags |= irqflag; - ret = serial8250_register_8250_port(&uart); + uart->port.iobase = p->iobase; + uart->port.membase = p->membase; + uart->port.irq = p->irq; + uart->port.irqflags = p->irqflags; + uart->port.uartclk = p->uartclk; + uart->port.regshift = p->regshift; + uart->port.iotype = p->iotype; + uart->port.flags = p->flags; + uart->port.mapbase = p->mapbase; + uart->port.mapsize = p->mapsize; + uart->port.hub6 = p->hub6; + uart->port.has_sysrq = p->has_sysrq; + uart->port.private_data = p->private_data; + uart->port.type = p->type; + uart->bugs = p->bugs; + uart->port.serial_in = p->serial_in; + uart->port.serial_out = p->serial_out; + uart->dl_read = p->dl_read; + uart->dl_write = p->dl_write; + uart->port.handle_irq = p->handle_irq; + uart->port.handle_break = p->handle_break; + uart->port.set_termios = p->set_termios; + uart->port.set_ldisc = p->set_ldisc; + uart->port.get_mctrl = p->get_mctrl; + uart->port.pm = p->pm; + uart->port.dev = &dev->dev; + uart->port.irqflags |= irqflag; + ret = serial8250_register_8250_port(uart); if (ret < 0) { dev_err(&dev->dev, "unable to register port at index %d " "(IO%lx MEM%llx IRQ%d): %d\n", i, -- 2.50.1