[PATCH] serial: 8250_platform: Fix structure initialization warning

[PATCH] serial: 8250_platform: Fix structure initialization warning

[Sunil V L]

Use memset to initialize the uart structure instead of universal zero
initializer to fix the below warning.

drivers/tty/serial/8250/8250_platform.c: In function 'serial8250_platform_probe':
drivers/tty/serial/8250/8250_platform.c:111:40: warning: excess elements in struct initializer
  111 |         struct uart_8250_port uart = { 0 };
      |                                        ^
drivers/tty/serial/8250/8250_platform.c:111:40: note: (near initialization for 'uart.port.lock.<anonymous>.rlock.raw_lock')

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407310023.h0JgJG1C-lkp@intel.com/
Fixes: d9e5a0ce2f16 ("serial: 8250_platform: Enable generic 16550A platform devices")
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 drivers/tty/serial/8250/8250_platform.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c
index bdfb16bed4f2..d8c3c169a620 100644
--- a/drivers/tty/serial/8250/8250_platform.c
+++ b/drivers/tty/serial/8250/8250_platform.c
@@ -108,11 +108,12 @@ void __init serial8250_isa_init_ports(void)
 static int serial8250_platform_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
-	struct uart_8250_port uart = { 0 };
+	struct uart_8250_port uart;
 	struct resource *regs;
 	unsigned char iotype;
 	int ret, line;
 
+	memset(&uart, 0, sizeof(uart));
 	regs = platform_get_resource(pdev, IORESOURCE_IO, 0);
 	if (regs) {
 		uart.port.iobase = regs->start;
-- 
2.43.0

Re: [PATCH] serial: 8250_platform: Fix structure initialization warning

[Stephen Rothwell]

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Hi Sunil,

On Wed,  7 Aug 2024 09:52:10 +0530 Sunil V L <sunilvl@ventanamicro.com> wrote:
>

> diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c
> index bdfb16bed4f2..d8c3c169a620 100644
> --- a/drivers/tty/serial/8250/8250_platform.c
> +++ b/drivers/tty/serial/8250/8250_platform.c
> @@ -108,11 +108,12 @@ void __init serial8250_isa_init_ports(void)
>  static int serial8250_platform_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> -	struct uart_8250_port uart = { 0 };
> +	struct uart_8250_port uart;

Does just using "{ }" as an initialiser work without warning?

-- 
Cheers,
Stephen Rothwell

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Re: [PATCH] serial: 8250_platform: Fix structure initialization warning

[Sunil V L]

Hi Stephen,

On Wed, Aug 07, 2024 at 03:13:52PM +1000, Stephen Rothwell wrote:
> Hi Sunil,
> 
> On Wed,  7 Aug 2024 09:52:10 +0530 Sunil V L <sunilvl@ventanamicro.com> wrote:
> >
> 
> > diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c
> > index bdfb16bed4f2..d8c3c169a620 100644
> > --- a/drivers/tty/serial/8250/8250_platform.c
> > +++ b/drivers/tty/serial/8250/8250_platform.c
> > @@ -108,11 +108,12 @@ void __init serial8250_isa_init_ports(void)
> >  static int serial8250_platform_probe(struct platform_device *pdev)
> >  {
> >  	struct device *dev = &pdev->dev;
> > -	struct uart_8250_port uart = { 0 };
> > +	struct uart_8250_port uart;
> 
> Does just using "{ }" as an initialiser work without warning?
> 
I tried that and at least on this architecture/compiler combination, the
warning is gone. However, I was not sure about it since gcc man page
indicates such initialization is valid for C++.

Quoting gcc manpage:

-Wmissing-field-initializers

In C this option does not warn about the universal zero initializer ‘{ 0 }’:
struct s { int f, g, h; };
struct s x = { 0 };

Likewise, in C++ this option does not warn about the empty { } initializer, for
example:
struct s { int f, g, h; };
s x = { };

So, I thought doing memset is probably safer which should work across
architectures/compiler combinations.

Thanks,
Sunil

Re: [PATCH] serial: 8250_platform: Fix structure initialization warning

[Greg Kroah-Hartman]

On Wed, Aug 07, 2024 at 09:52:10AM +0530, Sunil V L wrote:
> Use memset to initialize the uart structure instead of universal zero
> initializer to fix the below warning.
> 
> drivers/tty/serial/8250/8250_platform.c: In function 'serial8250_platform_probe':
> drivers/tty/serial/8250/8250_platform.c:111:40: warning: excess elements in struct initializer
>   111 |         struct uart_8250_port uart = { 0 };
>       |                                        ^
> drivers/tty/serial/8250/8250_platform.c:111:40: note: (near initialization for 'uart.port.lock.<anonymous>.rlock.raw_lock')
> 
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202407310023.h0JgJG1C-lkp@intel.com/
> Fixes: d9e5a0ce2f16 ("serial: 8250_platform: Enable generic 16550A platform devices")
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  drivers/tty/serial/8250/8250_platform.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_platform.c b/drivers/tty/serial/8250/8250_platform.c
> index bdfb16bed4f2..d8c3c169a620 100644
> --- a/drivers/tty/serial/8250/8250_platform.c
> +++ b/drivers/tty/serial/8250/8250_platform.c
> @@ -108,11 +108,12 @@ void __init serial8250_isa_init_ports(void)
>  static int serial8250_platform_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> -	struct uart_8250_port uart = { 0 };
> +	struct uart_8250_port uart;

{ } should be correct instead.

thanks,

greg k-h