On 2016年05月30日 22:33, Joe Perches wrote: > On Mon, 2016-05-30 at 22:21 +0800, Chen Gang wrote: >> No, they are not necessary. But for me, it will be more clearer, since >> in our kernel (at least in include/linux/), almost all Boolean functions >> use Boolean value or expression for return (and "!!" are often used). > > Opinions vary. > > There seem to be fewer than 20 !! uses in bool return > functions in include/linux/ >
ide.h:854 mlx4/driver.h:76 mlx5/device.h:744 mmzone.h:793 mtd/mtd.h:412 nilfs2_fs.h:568 nilfs2_fs.h:602 nilfs2_fs.h:667 nilfs2_fs.h:771 page-flags.h:711 pagemap.h:54 For me, we can change the related functions to Boolean functions directly. > Finding the quantity of bool conversions in include/linux > from something other than 0, 1, true, or false to 0 or 1 > is not trivial, but it is non-zero and seems rather more > than 20. > [root@localhost linux]# grep -rn "\<return\>" * | grep ' & ' | grep -v "==" | grep -v '||' | grep -v 'struct' | grep -v '!=' | grep -v ',' | grep -v '?' | grep -v '!' | grep -v '&&' | wc -l 259 After give a glance, more than 60% are not for bool functions (so I guess about 100 area hint). But I guess, quite a few of none Boolean functions above can be changed to Boolean functions, too (but have to read more code). So I guess, about 200+ matches the hint (not use "!!" for & operation in Boolean functions) in the 1000+ Boolean functions in include/linux. All together, for me: The return statement is much special than normal statements: - It is related with function's type (non-return function, Boolean function, or normal function), not only related with type cast within the statement itself. - Even for normal function, the type cast in return statement is also better: when reading source code, return statements have much more chances to be read than the function return type. - For finding Boolean function in existing normal functions, we often read the return value to know about whether it is a Boolean function or not. So, I still suggest to add type cast explicitly in return statement. Welcome any ideas, suggestions, and completions. Thanks. -- Chen Gang (陈刚) Managing Natural Environments is the Duty of Human Beings.
