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resources: when allocate_resource() fails, leave resource untouched 

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.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Bjorn Helgaas 2009-11-02 10:45:36 -07:00 committed by Jesse Barnes
parent 03db42adfe
commit 1e5ad96790
1 changed files with 14 additions and 12 deletions
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26
kernel/resource.c
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@ -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;