On Sat, Dec 22, 2018 at 11:31 PM Eric Dumazet <eric.duma...@gmail.com> wrote: > > > > On 12/21/2018 12:27 PM, Deepa Dinamani wrote: > > Al Viro mentioned that there is probably a race condition > > lurking in accesses of sk_tstamp on 32-bit machines. > > > > sock->sk_tstamp is of type ktime_t which is always an s64. > > On a 32 bit architecture, we might run into situations of > > unsafe access as the access to the field becomes non atomic. > > > > Use seqlocks for synchronization. > > This allows us to avoid using spinlocks for readers as > > readers do not need mutual exclusion. > > > > Hi Deepa > > Please come up with something that has zero added costs for 64bit kernels. > > Most of us do not really care about 32bit kernels anymore, so we do not want > to slow > down 64bits kernels for such things. > > Look at include/linux/u64_stats_sync.h for initial thoughts.
This is similar to what I did here. But, I can add a few ifdef's to make this code a noop on 64 bit arches. I will include this in my next update. I'm assuming there is no contention on whether writers need exclusive access and hence requiring a lock here. Let me know otherwise. Thanks, Deepa
