> On Wed, May 15, 2024 at 03:17:25PM +0000, Jiasheng Jiang wrote: >> Return 0 to indicate failure and return "len" to indicate success. >> It was hard to distinguish success or failure if "len" equals the error >> code after the implicit cast. >> Moreover, eliminating implicit cast is a better practice. > > According to whom? > Programmers can easily overlook implicit casts, leading to unknown behavior (e.g., this bug). Converting implicit casts to explicit casts can help prevent future errors. > Merits of your ex cathedra claims aside, you do realize that functions > have calling conventions because they are, well, called, right? > And changing the value returned in such and such case should be > accompanied with the corresponding change in the _callers_. > > Al, wondering if somebody had decided to play with LLM... As the comment shows that "ret = len; /* on success, claim we got the whole input */", the return value should be checked to determine whether it equals "len". Moreover, if "len" is 0, the previous copy_from_user() will fail and return an error. Therefore, 0 is an illegal value for "len". Besides, in the linux kernel, all the callers of simple_attr_write_xsigned() return the return value of simple_attr_write_xsigned(). -Jiasheng
