On Wed, Nov 23, 2011 at 11:11:08AM +0100, Michael Holzheu wrote:
> From: Michael Holzheu <holzheu at linux.vnet.ibm.com>
>
> Currently it is possible to set the crash_size via the sysfs
> /sys/kernel/kexec_crash_size even if no crash kernel memory has
> been defined with the "crashkernel" parameter. In this case
> "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
> Unfortunately resource_size(&crashk_res) returns 1 in this case.
> This breaks the s390 implementation of crash_(un)map_reserved_pages().
>
> To fix the problem the correct "old_size" is now calculated in
> crash_shrink_memory(). "old_size is set to "0" if crashk_res is
> not initialized. With this change crash_shrink_memory() will do nothing,
> when "crashk_res" is not initialized. It will return "0" for
> "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
> "echo [not zero] > /sys/kernel/kexec_crash_size".
>
> Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
> ---
> kernel/kexec.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran
> int crash_shrink_memory(unsigned long new_size)
> {
> int ret = 0;
> - unsigned long start, end;
> + unsigned long start, end, old_size;
>
> mutex_lock(&kexec_mutex);
>
> @@ -1141,10 +1141,10 @@ int crash_shrink_memory(unsigned long ne
> }
> start = crashk_res.start;
> end = crashk_res.end;
> -
> - if (new_size >= end - start + 1) {
> + old_size = (end == 0) ? 0 : end - start + 1;
> + if (new_size >= old_size) {
> ret = -EINVAL;
> - if (new_size == end - start + 1)
> + if (new_size == old_size)
> ret = 0;
I wonder if while we are here we could clean up the logic above a little.
To my mind both
ret = new_size == old_size ? 0 : -EINVAL;
and
if (new_size == old_size)
ret = 0;
else
ret = -EINVAL;
are easier on the eyes than the current logic.
> goto unlock;
> }
But I am happy with the patch without my above suggestion.
Reviewed-by-by: Simon Horman <horms at verge.net.au>
