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kexec: improve the readability of crash_shrink_memory() 

The major adjustments are:
1. end = start + new_size.
   The 'end' here is not an accurate representation, because it is not the
   new end of crashk_res, but the start of ram_res, difference 1. So
   eliminate it and replace it with ram_res->start.
2. Use 'ram_res->start' and 'ram_res->end' as arguments to
   crash_free_reserved_phys_range() to indicate that the memory covered by
   'ram_res' is released from the crashk. And keep it close to
   insert_resource().
3. Replace 'if (start == end)' with 'if (!new_size)', clear indication that
   all crashk memory will be shrunken.

No functional change.

Link: https://lkml.kernel.org/r/20230527123439.772-5-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Cong Wang <amwang@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Zhen Lei 2023-05-27 20:34:37 +08:00 committed by Andrew Morton
parent f7f567b95b
commit 8a7db7790a
1 changed files with 5 additions and 10 deletions
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15
kernel/kexec_core.c
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@ -1108,7 +1108,6 @@ ssize_t crash_get_memory_size(void)
int crash_shrink_memory(unsigned long new_size)
{
int ret = 0;
unsigned long start, end;
unsigned long old_size;
struct resource *ram_res;
@ -1119,9 +1118,7 @@ int crash_shrink_memory(unsigned long new_size)
ret = -ENOENT;
goto unlock;
}
start = crashk_res.start;
end = crashk_res.end;
old_size = (end == 0) ? 0 : end - start + 1;
old_size = !crashk_res.end ? 0 : resource_size(&crashk_res);
new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN);
if (new_size >= old_size) {
ret = (new_size == old_size) ? 0 : -EINVAL;
@ -1134,22 +1131,20 @@ int crash_shrink_memory(unsigned long new_size)
goto unlock;
}
end = start + new_size;
crash_free_reserved_phys_range(end, crashk_res.end);
ram_res->start = end;
ram_res->start = crashk_res.start + new_size;
ram_res->end = crashk_res.end;
ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
ram_res->name = "System RAM";
if (start == end) {
if (!new_size) {
release_resource(&crashk_res);
crashk_res.start = 0;
crashk_res.end = 0;
} else {
crashk_res.end = end - 1;
crashk_res.end = ram_res->start - 1;
}
crash_free_reserved_phys_range(ram_res->start, ram_res->end);
insert_resource(&iomem_resource, ram_res);
unlock: