On Wed, Mar 16, 2016 at 09:14:44AM +0100, Ingo Molnar wrote: > Yeah, so in the perf tooling build we do have -Wshadow to catch such mishaps, > but not in the main kernel build. > > ... and yes, if I add it via the patch below the bug gets warned about: > > include/linux/atomic.h:561:15: note: shadowed declaration is here > typeof(ptr) __ptr = (ptr); \ > ^ > kernel/sched/core.c:332:11: note: in expansion of macro ‘xchg_or’ > return !(xchg_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLA > > ... but I also get a ton of other warnings, just when building a single > kernel/sched/core.o file: > > ./arch/x86/include/asm/bitops.h:396:28: warning: declaration of ‘ffs’ > shadows a built-in function [-Wshadow] > ./arch/x86/include/asm/bitops.h:396:28: warning: declaration of ‘ffs’ > shadows a built-in function [-Wshadow] > include/linux/jiffies.h:422:60: warning: declaration of ‘jiffies’ shadows a > global declaration [-Wshadow] > ./arch/x86/include/asm/io_apic.h:187:54: warning: declaration of ‘apic’ > shadows a global declaration [-Wshadow] > ./arch/x86/include/asm/bitops.h:396:28: warning: declaration of ‘ffs’ > shadows a built-in function [-Wshadow] > include/linux/jiffies.h:422:60: warning: declaration of ‘jiffies’ shadows a > global declaration [-Wshadow] > ./arch/x86/include/asm/io_apic.h:187:54: warning: declaration of ‘apic’ > shadows a global declaration [-Wshadow] > include/linux/kernel.h:750:12: warning: declaration of ‘_min1’ shadows a > previous local [-Wshadow] > include/linux/kernel.h:750:12: warning: declaration of ‘_min1’ shadows a > previous local [-Wshadow] > include/linux/kernel.h:751:12: warning: declaration of ‘_min2’ shadows a > previous local [-Wshadow] > kernel/sched/sched.h:308:43: warning: declaration of ‘down’ shadows a global > declaration [-Wshadow] > kernel/sched/sched.h:308:60: warning: declaration of ‘up’ shadows a global > declaration [-Wshadow] > kernel/sched/auto_group.h:44:55: warning: declaration of ‘init_task’ shadows > a global declaration [-Wshadow] > kernel/sched/core.c:635:20: warning: declaration of ‘down’ shadows a global > declaration [-Wshadow] > kernel/sched/core.c:635:37: warning: declaration of ‘up’ shadows a global > declaration [-Wshadow]
Heh, what else can we expect from global functions named up() and down() in a millions-lines C project :-) > > and yes, I'd say most of these are signatures of sloppy macros and sloppy > variable > names - but it would be a ton of work to eliminate these warnings. Yeah that's what I was afraid of. Thanks for trying it though!
