Messages in this thread | | | Date | Thu, 30 Apr 2009 14:45:26 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Detect and warn on atomic_inc/atomic_dec wrapping around |
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On Thu, 30 Apr 2009 19:39:50 +0530 Nikanth Karthikesan <knikanth@novell.com> wrote:
>
If I had a dollar for each wordwrapped patch I get sent...
> Detect and warn on atomic_inc/atomic_dec overflow. > > Add a debug option to detect and warn when the 32-bit atomic_t overflows > during atomic_inc and atomic_dec. >
OK.
I'll beef the changelog up a bit - this one is wimpy.
The question is: do we put this in mainline? I guess we might as well give it a shot. It may well find bugs and it might also trigger false positives. We can then fix the bugs and decide whether the false positives warrant reverting it again, all very easy.
> +#include <asm/bug.h>
checkpatch says
WARNING: Use #include <linux/bug.h> instead of <asm/bug.h> #215: FILE: include/asm-generic/atomic.h:11: +#include <asm/bug.h>
Was this an oversight, or did you try using linux/bug.h and discovered some problem?
> index 812c282..773c1a4 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -17,6 +17,17 @@ config ENABLE_WARN_DEPRECATED > Disable this to suppress the "warning: 'foo' is deprecated > (declared at kernel/power/somefile.c:1234)" messages. > > +config HAVE_ARCH_DEBUG_ATOMIC > + bool > + > +config ENABLE_WARN_ATOMIC_INC_WRAP > + bool "Enable warning on atomic_inc()/atomic_dec() wrap" > + depends on HAVE_ARCH_DEBUG_ATOMIC > + default y > + help > + Enable printing a warning when atomic_inc() or atomic_dec() > + operation wraps around the 32-bit value. > +
Yes, I agree with `default y' for now. But we might want to turn it off again later. Adding that WARN to every atomic_inc/atomic_dec site must do terrible things to the kernel text footprint.
Of course, if we make if `default y' for a while and then switch it to `default n', the `y' state will linger for a very long time in all the kernel developers' .configs. Good! Very sneaky.
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