On 9/12/22 19:44, Sathyanarayanan Kuppuswamy wrote: >> and include the header (<linux/string.h> ?) for memchr_inv()? > One of the previous headers includes linux/string.h (I am not sure which one). > So why include it explicitly? Because it's a best practice. What happens is that you ride along on the coat tails of another #include, someone sees that include is no longer used and removes it. Then, your code is busted on some weird .config. *OR*, the header itself changes and doesn't #include the dependency you need. I guess you can go add this advice to Documentation/ if it's not there already somewhere.