Re: [PATCH v4 3/7] powerpc/fadump: un-register fadump on kexec path.

[Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>]

On 04/22/2018 07:28 AM, Nicholas Piggin wrote:
> On Fri, 20 Apr 2018 10:34:35 +0530
> Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com> wrote:
> 
>> From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
>>
>> otherwise the fadump registration in new kexec-ed kernel complains that
>> fadump is already registered. This makes new kernel to continue using
>> fadump registered by previous kernel which may lead to invalid vmcore
>> generation. Hence this patch fixes this issue by un-registering fadump
>> in fadump_cleanup() which is called during kexec path so that new kernel
>> can register fadump with new valid values.
> 
> Is this a bug fix that should go to previous kernels as well?

Yes.

> 
>>
>> Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
>> ---
>>  arch/powerpc/kernel/fadump.c |    3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>> index 43bfa535d0ea..16b3e8c5cae0 100644
>> --- a/arch/powerpc/kernel/fadump.c
>> +++ b/arch/powerpc/kernel/fadump.c
>> @@ -1276,6 +1276,9 @@ void fadump_cleanup(void)
>>  	/* Invalidate the registration only if dump is active. */
>>  	if (fw_dump.dump_active) {
>>  		fadump_invalidate_dump(fdm_active);
>> +	} else if (fw_dump.dump_registered) {
>> +		/* Un-register Firmware-assisted dump if it was registered. */
>> +		fadump_unregister_dump(&fdm);
>>  	}
>>  }
>>  
>>
>