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Subject: Re: [PATCH v2 3/8] crash_core: change parse_crashkernel() to support
 crashkernel=,high|low parsing
To:     Baoquan He <bhe@redhat.com>, linux-kernel@vger.kernel.org
Cc:     akpm@linux-foundation.org, catalin.marinas@arm.com,
        thunder.leizhen@huawei.com, dyoung@redhat.com, prudo@redhat.com,
        samuel.holland@sifive.com, kexec@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, x86@kernel.org
References: <20230829121610.138107-1-bhe@redhat.com>
 <20230829121610.138107-4-bhe@redhat.com>
From:   "Leizhen (ThunderTown)" <thunder.leizhen@huaweicloud.com>
Message-ID: <c4a1f96e-2c8d-a496-61f3-0299d77c5c84@huaweicloud.com>
Date:   Thu, 31 Aug 2023 10:56:58 +0800
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On 2023/8/29 20:16, Baoquan He wrote:
> Now parse_crashkernel() is a real entry point for all kinds of
> crahskernel parsing on any architecture.
> 
> And wrap the crahskernel=,high|low handling inside
> CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/crash_core.h |  6 ++++++
>  kernel/crash_core.c        | 28 +++++++++++++++++++++++++++-
>  2 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 2e76289699ff..85260bf4a734 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -77,6 +77,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len);
>  void final_note(Elf_Word *buf);
>  
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
> +#endif
> +#endif
> +
>  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base,
>  		unsigned long long *low_size, bool *high);
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index f6a5c219e2e1..355b0ab5189c 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -276,6 +276,9 @@ static int __init __parse_crashkernel(char *cmdline,
>  /*
>   * That function is the entry point for command line parsing and should be
>   * called from the arch-specific code.
> + *
> + * If crashkernel=,high|low is supported on architecture, non-NULL values
> + * should be passed to parameters 'low_size' and 'high'.
>   */
>  int __init parse_crashkernel(char *cmdline,
>  			     unsigned long long system_ram,
> @@ -291,7 +294,30 @@ int __init parse_crashkernel(char *cmdline,
>  				crash_base, NULL);
>  	if (!high)
>  		return ret;
> -
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +	else if (ret == -ENOENT) {
> +		ret = __parse_crashkernel(cmdline, 0, crash_size,
> +				crash_base, suffix_tbl[SUFFIX_HIGH]);
> +		if (ret || !*crash_size)
> +			return -1;

Change -1 to -EINVAL?

> +
> +		/*
> +		 * crashkernel=Y,low can be specified or not, but invalid value
> +		 * is not allowed.
> +		 */
> +		ret = __parse_crashkernel(cmdline, 0, low_size,
> +				crash_base, suffix_tbl[SUFFIX_LOW]);
> +		if (ret == -ENOENT)
> +			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> +		else if (ret)
> +			return -1;

return ret;

> +
> +		*high = true;
> +	} else if (ret || !*crash_size) {

This check can be moved outside of #ifdef. Because even '!high', it's completely
applicable. The overall adjustment is as follows:

-  	if (!high)
-  		return ret;

#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
	if (high && ret == -ENOENT) {
		... ...
		if (ret || !*crash_size)	//parse HIGH
		... ...
	}

	//At this point, *crash_size is not 0 and ret is 0.
	//We can also delete if (!*crash_size) above because it will be checked later.
#endif

	if (!*crash_size)
		ret = -EINVAL;

	return ret;

-  	return 0;

> +		/* The specified value is invalid */
> +		return -1;
> +	}
> +#endif
>  	return 0;
>  }
>  
> 

-- 
Regards,
  Zhen Lei