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SubjectRe: [PATCH] efi: cper: avoid using get_seconds()
On 18 June 2018 at 17:49, Arnd Bergmann <arnd@arndb.de> wrote:
> On Mon, Jun 18, 2018 at 5:47 PM, Ard Biesheuvel
> <ard.biesheuvel@linaro.org> wrote:
>> On 18 June 2018 at 16:17, Arnd Bergmann <arnd@arndb.de> wrote:
>
>>> - atomic64_set(&seq, ((u64)get_seconds()) << 32);
>>> + if (!atomic64_read(&seq)) {
>>> + time64_t time = ktime_get_real_seconds();
>>> +
>>> + /*
>>> + * This code is unlikely to still be needed in year 2106,
>>> + * but just in case, let's use a few more bits for timestamps
>>> + * after y2038 to be sure they keep increasing monotonically
>>> + * for the next few hundred years...
>>> + */
>>> + if (time < 0x80000000)
>>> + atomic64_set(&seq, (ktime_get_real_seconds()) << 32);
>>> + else
>>> + atomic64_set(&seq, 0x8000000000000000ull |
>>> + ktime_get_real_seconds() << 24);
>>> + }
>>
>> Given that these values are never decoded and interpreted as
>> timestamps, can't we simply switch to the second flavour immediately?
>
> I considered that, but the downside would be that all future filenames would
> come before all past file names.

Won't we have that same problem in 2038?

> I don't know if the order is important at
> all, but the current implementation at least looks like it's intended to keep
> all file names strictly sorted across boots.
>
> Arnd

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