serial: 8250_platform: Reduce stack usage in serial8250_probe_acpi()

The function serial8250_probe_acpi() in 8250_platform.c triggered a
    frame size warning:
drivers/tty/serial/8250/8250_platform.c: In function ‘serial8250_probe_acpi’:
drivers/tty/serial/8250/8250_platform.c:152:1: warning: the frame size of 1160 bytes is larger than 1024 bytes [-Wframe-larger-than=]

This patch reduces the stack usage by dynamically allocating the
`uart` structure using kzalloc(), rather than placing it on
the stack. This eliminates the overflow warning and improves kernel
robustness.

Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20250806215134.4921-2-abinashsinghlalotra@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c
index c0343bfb80647d1308f7a635be1eb08792beac65..9938aeb917d8538c512ce47624fae318b2d2911e 100644 (file)
--- a/drivers/tty/serial/8250/8250_platform.c
+++ b/drivers/tty/serial/8250/8250_platform.c
@@ -10,6 +10,7 @@
  */
 #include <linux/acpi.h>
 #include <linux/array_size.h>
+#include <linux/cleanup.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
@@ -110,41 +111,44 @@ void __init serial8250_isa_init_ports(void)
 static int serial8250_probe_acpi(struct platform_device *pdev)
 {
        struct device *dev = &pdev->dev;
-       struct uart_8250_port uart = { };
        struct resource *regs;
        int ret, line;
 
+       struct uart_8250_port *uart __free(kfree) = kzalloc(sizeof(*uart), GFP_KERNEL);
+       if (!uart)
+               return -ENOMEM;
+
        regs = platform_get_mem_or_io(pdev, 0);
        if (!regs)
                return dev_err_probe(dev, -EINVAL, "no registers defined\n");
 
        switch (resource_type(regs)) {
        case IORESOURCE_IO:
-               uart.port.iobase = regs->start;
+               uart->port.iobase = regs->start;
                break;
        case IORESOURCE_MEM:
-               uart.port.mapbase = regs->start;
-               uart.port.mapsize = resource_size(regs);
-               uart.port.flags = UPF_IOREMAP;
+               uart->port.mapbase = regs->start;
+               uart->port.mapsize = resource_size(regs);
+               uart->port.flags = UPF_IOREMAP;
                break;
        default:
                return -EINVAL;
        }
 
        /* default clock frequency */
-       uart.port.uartclk = 1843200;
-       uart.port.type = PORT_16550A;
-       uart.port.dev = &pdev->dev;
-       uart.port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
+       uart->port.uartclk = 1843200;
+       uart->port.type = PORT_16550A;
+       uart->port.dev = &pdev->dev;
+       uart->port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF;
 
-       ret = uart_read_and_validate_port_properties(&uart.port);
+       ret = uart_read_and_validate_port_properties(&uart->port);
        /* no interrupt -> fall back to polling */
        if (ret == -ENXIO)
                ret = 0;
        if (ret)
                return ret;
 
-       line = serial8250_register_8250_port(&uart);
+       line = serial8250_register_8250_port(uart);
        if (line < 0)
                return line;