[10/30] alpha: Clean-up the panic notifier code

The alpha panic notifier has some code issues, not following
the conventions of other notifiers. Also, it might halt the
machine but still it is set to run as early as possible, which
doesn't seem to be a good idea.

This patch cleans the code, and set the notifier to run as the
latest, following the same approach other architectures are doing.
Also, we remove the unnecessary include of a header already
included indirectly.

Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
---
 arch/alpha/kernel/setup.c | 36 +++++++++++++++---------------------
 1 file changed, 15 insertions(+), 21 deletions(-)

On 27/04/2022 19:49, Guilherme G. Piccoli wrote:
> The alpha panic notifier has some code issues, not following
> the conventions of other notifiers. Also, it might halt the
> machine but still it is set to run as early as possible, which
> doesn't seem to be a good idea.
> 
> This patch cleans the code, and set the notifier to run as the
> latest, following the same approach other architectures are doing.
> Also, we remove the unnecessary include of a header already
> included indirectly.
> 
> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
> Cc: Matt Turner <mattst88@gmail.com>
> Cc: Richard Henderson <rth@twiddle.net>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
> ---
>  arch/alpha/kernel/setup.c | 36 +++++++++++++++---------------------
>  1 file changed, 15 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
> index b4fbbba30aa2..d88bdf852753 100644
> --- a/arch/alpha/kernel/setup.c
> +++ b/arch/alpha/kernel/setup.c
> @@ -41,19 +41,11 @@
>  #include <linux/sysrq.h>
>  #include <linux/reboot.h>
>  #endif
> -#include <linux/notifier.h>
>  #include <asm/setup.h>
>  #include <asm/io.h>
>  #include <linux/log2.h>
>  #include <linux/export.h>
>  
> -static int alpha_panic_event(struct notifier_block *, unsigned long, void *);
> -static struct notifier_block alpha_panic_block = {
> -	alpha_panic_event,
> -        NULL,
> -        INT_MAX /* try to do it first */
> -};
> -
>  #include <linux/uaccess.h>
>  #include <asm/hwrpb.h>
>  #include <asm/dma.h>
> @@ -435,6 +427,21 @@ static const struct sysrq_key_op srm_sysrq_reboot_op = {
>  };
>  #endif
>  
> +static int alpha_panic_event(struct notifier_block *this,
> +			     unsigned long event, void *ptr)
> +{
> +	/* If we are using SRM and serial console, just hard halt here. */
> +	if (alpha_using_srm && srmcons_output)
> +		__halt();
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block alpha_panic_block = {
> +	.notifier_call = alpha_panic_event,
> +	.priority = INT_MIN, /* may not return, do it last */
> +};
> +
>  void __init
>  setup_arch(char **cmdline_p)
>  {
> @@ -1427,19 +1434,6 @@ const struct seq_operations cpuinfo_op = {
>  	.show	= show_cpuinfo,
>  };
>  
> -
> -static int
> -alpha_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
> -{
> -#if 1
> -	/* FIXME FIXME FIXME */
> -	/* If we are using SRM and serial console, just hard halt here. */
> -	if (alpha_using_srm && srmcons_output)
> -		__halt();
> -#endif
> -        return NOTIFY_DONE;
> -}
> -
>  static __init int add_pcspkr(void)
>  {
>  	struct platform_device *pd;


Hi folks, I'm updating Richard's email and re-sending the V1, any
reviews are greatly appreciated!

Cheers,


Guilherme

On Mon 2022-05-09 11:13:17, Guilherme G. Piccoli wrote:
> On 27/04/2022 19:49, Guilherme G. Piccoli wrote:
> > The alpha panic notifier has some code issues, not following
> > the conventions of other notifiers. Also, it might halt the
> > machine but still it is set to run as early as possible, which
> > doesn't seem to be a good idea.

Yeah, it is pretty strange behavior.

I looked into the history. This notifier was added into the alpha code
in 2.4.0-test2pre2. In this historic code, the default panic() code
either rebooted after a timeout or ended in a infinite loop. There
was not crasdump at that times.

The notifier allowed to change the behavior. There were 3 notifiers:

   + mips and mips64 ended with blinking in panic()
   + alpha did __halt() in this srm case

They both still do this. I guess that it is some historic behavior
that people using these architectures are used to.

Anyway, it makes sense to do this as the last notifier after
dumping other information.

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

On 10/05/2022 11:16, Petr Mladek wrote:
> [...]
> Yeah, it is pretty strange behavior.
> 
> I looked into the history. This notifier was added into the alpha code
> in 2.4.0-test2pre2. In this historic code, the default panic() code
> either rebooted after a timeout or ended in a infinite loop. There
> was not crasdump at that times.
> 
> The notifier allowed to change the behavior. There were 3 notifiers:
> 
>    + mips and mips64 ended with blinking in panic()
>    + alpha did __halt() in this srm case
> 
> They both still do this. I guess that it is some historic behavior
> that people using these architectures are used to.
> 
> Anyway, it makes sense to do this as the last notifier after
> dumping other information.
> 
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> 
> Best Regards,
> Petr

Thanks a bunch for the review - added your tag for V2 =)