From: Pan Xinhui <xinhuix....@intel.com>
It's more reasonable to unlock memtype_lock right after
rbt_memtype_check_insert. All pat_rbtree operations need to be performed
while holding the memtype_lock. But codes like kfree, pr_info, etc have
nothing to do with this lock. So move spin_unlock a little ahead.
If *new* succeed to be stored into the rb-tree, we might hit panic.
Because we access *new* in dprintk "cattr_name(new->type)". Data stored
in the rb-tree might be freed at any possbile time. It's abviously wrong
to access such data without lock held.
We use actual_type instead of new->type in dprintk. Two benefits, 1) We
don't touch *new* here now so panic can be avoided. 2) As new->type is
same with *new_type, We needn't to print it again, what's more, this
actual_type's output can help dubug. When new_type is NULL, actual_type
is equal to new->type, So no key information is lost.
Do a minor codes style improvement.
Signed-off-by: Pan Xinhui <xinhuix....@intel.com>
---
change from v4:
codes style improvement by removing {}.
@sorry for that, make reviewing a patch so much complex, this should be
done in V4.
change from v3:
output actual_type instead of new->type.
codes style improvement.
update comments.
change from v2:
update comments.
change from V1:
fix an access of *new* without memtype_lock held.
---
arch/x86/mm/pat.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 188e3e0..268b2c8 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -520,14 +520,10 @@ int reserve_memtype(u64 start, u64 end, enum
page_cache_mode req_type,
*new_type = actual_type;
is_range_ram = pat_pagerange_is_ram(start, end);
- if (is_range_ram == 1) {
-
- err = reserve_ram_pages_type(start, end, req_type, new_type);
-
- return err;
- } else if (is_range_ram < 0) {
+ if (is_range_ram == 1)
+ return reserve_ram_pages_type(start, end, req_type, new_type);
+ else if (is_range_ram < 0)
return -EINVAL;
- }
new = kzalloc(sizeof(struct memtype), GFP_KERNEL);
if (!new)
@@ -538,22 +534,19 @@ int reserve_memtype(u64 start, u64 end, enum
page_cache_mode req_type,
new->type = actual_type;
spin_lock(&memtype_lock);
-
err = rbt_memtype_check_insert(new, new_type);
+ spin_unlock(&memtype_lock);
+
if (err) {
pr_info("x86/PAT: reserve_memtype failed [mem %#010Lx-%#010Lx],
track %s, req %s\n",
start, end - 1,
cattr_name(new->type), cattr_name(req_type));
kfree(new);
- spin_unlock(&memtype_lock);
-
return err;
}
- spin_unlock(&memtype_lock);
-
dprintk("reserve_memtype added [mem %#010Lx-%#010Lx], track %s, req %s,
ret %s\n",
- start, end - 1, cattr_name(new->type), cattr_name(req_type),
+ start, end - 1, cattr_name(actual_type), cattr_name(req_type),
new_type ? cattr_name(*new_type) : "-");
return err;
--
1.9.1
--
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