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Subject[PATCH] resources: when allocate_resource() fails, leave resource untouched
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When "allocate_resource(root, new, size, ...)" fails, we currently
clobber "new". This is inconvenient for the caller, who might care
about the original contents of the resource.

For example, when pci_bus_alloc_resource() fails, the "can't allocate
mem resource %pR" message from pci_assign_resources() currently contains
junk for the resource start/end.

This patch delays the "new" update until we're about to return success.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
---
kernel/resource.c | 26 ++++++++++++++------------
1 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/kernel/resource.c b/kernel/resource.c
index fb11a58..dc15686 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -308,35 +308,37 @@ static int find_resource(struct resource *root, struct resource *new,
void *alignf_data)
{
struct resource *this = root->child;
+ resource_size_t start, end;

- new->start = root->start;
+ start = root->start;
/*
* Skip past an allocated resource that starts at 0, since the assignment
* of this->start - 1 to new->end below would cause an underflow.
*/
if (this && this->start == 0) {
- new->start = this->end + 1;
+ start = this->end + 1;
this = this->sibling;
}
for(;;) {
if (this)
- new->end = this->start - 1;
+ end = this->start - 1;
else
- new->end = root->end;
- if (new->start < min)
- new->start = min;
- if (new->end > max)
- new->end = max;
- new->start = ALIGN(new->start, align);
+ end = root->end;
+ if (start < min)
+ start = min;
+ if (end > max)
+ end = max;
+ start = ALIGN(start, align);
if (alignf)
alignf(alignf_data, new, size, align);
- if (new->start < new->end && new->end - new->start >= size - 1) {
- new->end = new->start + size - 1;
+ if (start < end && end - start >= size - 1) {
+ new->start = start;
+ new->end = start + size - 1;
return 0;
}
if (!this)
break;
- new->start = this->end + 1;
+ start = this->end + 1;
this = this->sibling;
}
return -EBUSY;


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