On Thu, 2019-03-07 at 17:25 +0000, Russell King - ARM Linux admin wrote: > On Thu, Mar 07, 2019 at 09:19:04AM -0800, Joe Perches wrote: > > On Thu, 2019-03-07 at 10:14 +0100, Arnd Bergmann wrote: > > > On 32-bit ARM, I got a link failure in futex_init() when building > > > with clang in some random configurations: > > > > > > kernel/futex.o:(.text.fixup+0x5c): relocation truncated to fit: > > > R_ARM_JUMP24 against `.init.text' > > > > > > As far as I can tell, the problem is that a branch is over 16MB > > > apart in those configurations, but only if it branches back to > > > the init text. > > > > > > Marking the futex_detect_cmpxchg() function as noinline and > > > not __init avoids the problem for me. > > > > Perhaps the __init and __exit #defines should be noinline > > to allow discarding of the code. > > How does that help this case?
It doesn't particularly. It does help any other case that might arise. > It seems to me to be completely sane to have: > > static void __init foo(...) > { > } > > static int __init foo_init(...) > { > foo(); > } > > and have the expectation that the compiler _can_, if it desires, inline > foo() into foo_init(). True, but init function performance requirements are generally trivial and isolating the possibility of defects like this seems a reasonable trade-off to me.