On 10/19/20 12:42 PM, Nick Desaulniers wrote: > On Sat, Oct 17, 2020 at 10:43 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: >> On Sat, Oct 17, 2020 at 09:09:28AM -0700, trix@xxxxxxxxxx wrote: >>> From: Tom Rix <trix@xxxxxxxxxx> >>> >>> This is a upcoming change to clean up a new warning treewide. >>> I am wondering if the change could be one mega patch (see below) or >>> normal patch per file about 100 patches or somewhere half way by collecting >>> early acks. >> Please break it up into one-patch-per-subsystem, like normal, and get it >> merged that way. >> >> Sending us a patch, without even a diffstat to review, isn't going to >> get you very far... > Tom, > If you're able to automate this cleanup, I suggest checking in a > script that can be run on a directory. Then for each subsystem you > can say in your commit "I ran scripts/fix_whatever.py on this subdir." > Then others can help you drive the tree wide cleanup. Then we can > enable -Wunreachable-code-break either by default, or W=2 right now > might be a good idea. I should have waited for Joe Perches's fixer addition to checkpatch :) The easy fixes I did only cover about 1/2 of the problems. Remaining are mostly nested switches, which from a complexity standpoint is bad. > > Ah, George (gbiv@, cc'ed), did an analysis recently of > `-Wunreachable-code-loop-increment`, `-Wunreachable-code-break`, and > `-Wunreachable-code-return` for Android userspace. From the review: > ``` > Spoilers: of these, it seems useful to turn on > -Wunreachable-code-loop-increment and -Wunreachable-code-return by > default for Android In my simple add-a-cflag bot, i see there are about 250 issues for -Wunreachable-code-return. I'll see about doing this one next. > ... > While these conventions about always having break arguably became > obsolete when we enabled -Wfallthrough, my sample turned up zero > potential bugs caught by this warning, and we'd need to put a lot of > effort into getting a clean tree. So this warning doesn't seem to be > worth it. > ``` > Looks like there's an order of magnitude of `-Wunreachable-code-break` > than the other two. > > We probably should add all 3 to W=2 builds (wrapped in cc-option). > I've filed https://github.com/ClangBuiltLinux/linux/issues/1180 to > follow up on. Yes, i think think these should be added. Tom
