hi Kees Cook,
On 2020/5/12 PM 1:15, Kees Cook wrote:
> On Tue, May 12, 2020 at 11:55:20AM +0800, WeiXiong Liao wrote:
>> On 2020/5/12 AM 7:32, Kees Cook wrote:
>>> [...]
>>> +struct psz_context {
>>> + struct pstore_zone **kpszs;
>>> + unsigned int kmsg_max_cnt;
>>> + unsigned int kmsg_read_cnt;
>>> + unsigned int kmsg_write_cnt;
>>> + /*
>>> + * These counters should be calculated during recovery.
>>> + * It records the oops/panic times after crashes rather than boots.
>>> + */
>>> + unsigned int oops_counter;
>>> + unsigned int panic_counter;
>>
>> oops/panic_counter is designed to count the crash times since the
>> linux kernel was installed. pstore/zone lookup the max counter from all
>> valid kmsg zones when recovery and saves them to oops/panic_counter.
>> However, they are unable to get real number if we remove files. It's
>> not serious, we can fix it after this series.
>
> Since the kernel was installed? I don't see a kernel version check in
> here? Or do you mean "since ever", in that it's a rolling count?
>
Yes, "since ever".
>> And since pstore supports "max_reason", should pstore/zone count for
>> other reason?
>
> For now, no. I opted to try to keep this as simple as possible a port
> from dump_oops to max_reason for now.
>
OK.
>>> +static inline int psz_kmsg_erase(struct psz_context *cxt,
>>> + struct pstore_zone *zone, struct pstore_record *record)
>>> +{
>>> + struct psz_buffer *buffer = zone->buffer;
>>> + struct psz_kmsg_header *hdr =
>>> + (struct psz_kmsg_header *)buffer->data;
>>> +
>>> + if (unlikely(!psz_ok(zone)))
>>> + return 0;
>>> + /* this zone is already updated, no need to erase */
>>> + if (record->count != hdr->counter)
>>> + return 0;
>>
>> These codes is to fix bug that user remove files on pstore filesystem
>> but kmsg zone is already updated and pstore/zone should not erase
>> zone. It work for oops and panic because the count number is increasing.
>> However, it's useless for other reason of kmsg. We can fix it after this
>> series.
>
> Okay, sounds good.
>
--
WeiXiong Liao
