lkml.org 
[lkml]   [2011]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
    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>



    \
     
     \ /
      Last update: 2011-11-23 11:25    [W:3.250 / U:0.200 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site