Re: [Y2038] [PATCH] efi: cper: avoid using get_seconds()

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. 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