serial: 8250_platform: Reduce stack usage in serial8250_probe_platform()

 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 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/20250806215134.4921-3-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 9938aeb917d8538c512ce47624fae318b2d2911e..b27981340e769aeb9e38714c856d61cd743b230b 100644 (file)
--- a/drivers/tty/serial/8250/8250_platform.c
+++ b/drivers/tty/serial/8250/8250_platform.c
@@ -157,43 +157,44 @@ 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;
        int ret, i, irqflag = 0;
 
-       memset(&uart, 0, sizeof(uart));
+       struct uart_8250_port *uart __free(kfree) = kzalloc(sizeof(*uart), GFP_KERNEL);
+       if (!uart)
+               return -ENOMEM;
 
        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,