On Thu, Jan 10, 2019 at 11:48:13PM +0000, Jason Gunthorpe wrote: > +The Linux kernel bool type is an alias for the C99 _Bool type. bool values can > +only evaluate to 0 or 1, and implicit or explicit conversion to bool > +automatically converts the value to true or false. When using bool types the > +!! construction is not needed, which eliminates a class of bugs. > + > +When working with bool values the true and false definitions should be used > +instead of 0 and 1. > + > +bool function return types and stack variables are always fine to use whenever > +appropriate. Use of bool is encouraged to improve readability and is often a > +better option than 'int' for storing boolean values. It's awkward to start a sentence with a lower case letter. How about rephrasing this paragraph and the following one as: Using bool as the return type of a function or as a variable is always fine when appropriate. It often improves readability and is a better option than int for storing boolean values. Using bool in data structures is more debatable; its size and alignment can vary between architectures. > +Do not use bool if cache line layout or size of the value matters, its size > +and alignment varies based on the compiled architecture. Structures that are > +optimized for alignment and size should not use bool. > + > +If a structure has many true/false values, consider consolidating them into a > +bitfield with 1 bit members, or using an appropriate fixed width type, such as > +u8.
