Messages in this thread | | | Date | Wed, 23 Nov 2011 19:22:15 +0900 | From | Simon Horman <> | Subject | Re: [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size |
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On Wed, Nov 23, 2011 at 11:11:08AM +0100, Michael Holzheu wrote: > From: Michael Holzheu <holzheu@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@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@verge.net.au>
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