Il 18/11/2011 00:05, Andrew Morton ha scritto:
On Wed, 16 Nov 2011 14:56:06 -0500 Andrei Warkentin<andreiw@vmware.com> wrote:
1 is a power of two, therefore rounddown_pow_of_two(1) should return 1. It does in case the argument is a variable but in case it's a constant it behaves wrong and returns 0. Probably nobody ever did it so this was never noticed, however net/drivers/vmxnet3 with latest GCC does and breaks on unicpu systems.
This is similar to Rolf's patch to roundup_pow_of_two(1).
Cc: Rolf Eike Beer<eike-kernel@sf-tec.de> Cc: opensuse-kernel@opensuse.org Reviewed-by: Jesper Juhl<jj@chaosbits.net> Signed-off-by: Andrei Warkentin<andreiw@vmware.com> --- include/linux/log2.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/include/linux/log2.h b/include/linux/log2.h index 25b8086..ccda848 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -185,7 +185,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n) #define rounddown_pow_of_two(n) \ ( \ __builtin_constant_p(n) ? ( \ - (n == 1) ? 0 : \ + (n == 1) ? 1 : \ (1UL<< ilog2(n))) : \ __rounddown_pow_of_two(n) \ )
I assume that nobody has gone off and checked whether all current callers will survive this change. If they had, they'd have looked in drivers/char/ramoops.c and seen:
rounddown_pow_of_two(pdata->mem_size); rounddown_pow_of_two(pdata->record_size);
These operations are no-ops. It should be
pdata->mem_size = rounddown_pow_of_two(pdata->mem_size); pdata->record_size = rounddown_pow_of_two(pdata->record_size);
Marco or Sergio: please fix, test and send it over sometime?
Ok, I'll look at it. Marco -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org