linux-kernel - Re: [PATCH v3 1/5] crash: move crashkernel parsing and vmcore related code under CONFIG_CRASH

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Message-Id: <551a6147-98a2-8d08-8800-192d4d28fba0@linux.vnet.ibm.com>
Date:   Thu, 5 Jan 2017 23:12:41 +0530
From:   Hari Bathini <hbathini@...ux.vnet.ibm.com>
To:     Dave Young <dyoung@...hat.com>
Cc:     linux-kernel@...r.kernel.org, fenghua.yu@...el.com,
        tony.luck@...el.com, linux-ia64@...r.kernel.org,
        kexec@...ts.infradead.org,
        Mahesh J Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        ebiederm@...ssion.com, Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org, vgoyal@...hat.com
Subject: Re: [PATCH v3 1/5] crash: move crashkernel parsing and vmcore related
 code under CONFIG_CRASH_CORE

Hi Dave,


On Thursday 05 January 2017 11:47 AM, Dave Young wrote:
> Hi, Hari
>
> On 01/02/17 at 07:43pm, Hari Bathini wrote:
>> Traditionally, kdump is used to save vmcore in case of a crash. Some
>> architectures like powerpc can save vmcore using architecture specific
>> support instead of kexec/kdump mechanism. Such architecture specific
>> support also needs to reserve memory, to be used by dump capture kernel.
>> crashkernel parameter can be a reused, for memory reservation, by such
>> architecture specific infrastructure.
>>
>> But currently, code related to vmcoreinfo and parsing of crashkernel
>> parameter is built under CONFIG_KEXEC_CORE. This patch introduces
>> CONFIG_CRASH_CORE and moves the above mentioned code under this config,
>> allowing code reuse without dependency on CONFIG_KEXEC. There is no
>> functional change with this patch.
>>
>> Signed-off-by: Hari Bathini <hbathini@...ux.vnet.ibm.com>
>> ---
>>
>> Changes from v2:
>> * Used CONFIG_CRASH_CORE instead of CONFIG_KEXEC_CORE at
>>    appropriate places in printk and ksysfs.
>>
>>
>>   arch/Kconfig               |    4
>>   include/linux/crash_core.h |   65 ++++++
>>   include/linux/kexec.h      |   57 ------
>>   include/linux/printk.h     |    4
>>   kernel/Makefile            |    1
>>   kernel/crash_core.c        |  445 ++++++++++++++++++++++++++++++++++++++++++++
>>   kernel/kexec_core.c        |  404 ----------------------------------------
>>   kernel/ksysfs.c            |    8 +
>>   kernel/printk/printk.c     |    6 -
>>   9 files changed, 531 insertions(+), 463 deletions(-)
>>   create mode 100644 include/linux/crash_core.h
>>   create mode 100644 kernel/crash_core.c
>>
> [snip]
>
>>   #ifndef CONFIG_TINY_RCU
>> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
>> index 8b26964..d0dfebd 100644
>> --- a/kernel/printk/printk.c
>> +++ b/kernel/printk/printk.c
>> @@ -32,7 +32,7 @@
>>   #include <linux/bootmem.h>
>>   #include <linux/memblock.h>
>>   #include <linux/syscalls.h>
>> -#include <linux/kexec.h>
>> +#include <linux/crash_core.h>
>>   #include <linux/kdb.h>
>>   #include <linux/ratelimit.h>
>>   #include <linux/kmsg_dump.h>
>> @@ -951,7 +951,7 @@ const struct file_operations kmsg_fops = {
>>   	.release = devkmsg_release,
>>   };
>>   
>> -#ifdef CONFIG_KEXEC_CORE
>> +#ifdef CONFIG_CRASH_CORE
>>   /*
>>    * This appends the listed symbols to /proc/vmcore
>>    *
>> @@ -960,7 +960,7 @@ const struct file_operations kmsg_fops = {
>>    * symbols are specifically used so that utilities can access and extract the
>>    * dmesg log from a vmcore file after a crash.
>>    */
>> -void log_buf_kexec_setup(void)
>> +void log_buf_crash_setup(void)
> I can not think of any better name about the CONFIG_CRASH_CORE though I
> feel it is not excellent so personally I can live with it.
>
> But for this function name log_buf_crash_setup is too general, I can not get
> what it is doing from the name, how about change it to log_buf_vmcoreinfo_setup

log_buf_vmcoreinfo_setup is appropriate.  Also dropped hard-coded values
for DIV_ROUND_UP().
Posted v4 with these changes..

Thanks
Hari