On Mon, May 16, 2022 at 06:10:23AM -0700, Guenter Roeck wrote: > On Mon, Feb 28, 2022 at 11:27:43AM +0100, Arnd Bergmann wrote: > > From: Arnd Bergmann <arnd@xxxxxxxx> > > > > During a patch discussion, Linus brought up the option of changing > > the C standard version from gnu89 to gnu99, which allows using variable > > declaration inside of a for() loop. While the C99, C11 and later standards > > introduce many other features, most of these are already available in > > gnu89 as GNU extensions as well. > > The downside is that backporting affected patches to older kernel branches > now fails with error messages such as > > mm/kfence/core.c: In function ‘kfence_init_pool’: > mm/kfence/core.c:595:2: error: ‘for’ loop initial declarations are only allowed in C99 or C11 mode > > Just something to keep in mind when writing patches. I just ran across this very issue on this commit. It's an easy fixup for 5.17.y to make this work, so I did that in my tree. If this gets to be too much, we might need to reconsider adding c11 to older stable kernels. thanks, greg k-h
