On Sun, Sep 11, 2011 at 12:49:59PM +1200, Michal Ludvig wrote:
> On 09/09/2011 11:34 PM, Ram Pai wrote:
> >My patch assumed that the resource-range returned by __find_resource() will
> >always return a range that when allocated through request_resource() will not
> >lead to conflicts. However your platform somehow breaks that assumption.
> >
> >I have rearranged the code to ensure that request_resource() returns
> >without conflicting overlaps; before returning success.
>
> Hi Ram,
>
> applied your patch on top of 3.1.0-rc5 and unfortunately it's not
> much better than it was. Log attached.
>
> BTW Kernel bugzilla seems to be down, will update it later.
>
> Michal
Hi Michal,
Attaching yet another patch. Please revert the earlier patch
and apply this. I dont know if this will solve your problem.
if it does not, then I will have to send you a patch with lots
of printk to understand the root cause. I suppose we can continue
our discussion on bugzilla. Thanks for your help.
diff --git a/kernel/resource.c b/kernel/resource.c
index 3ff4017..4fcba8f 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -156,11 +156,7 @@ static struct resource * __request_resource(struct resource *root, struct resour
resource_size_t end = new->end;
struct resource *tmp, **p;
- if (end < start)
- return root;
- if (start < root->start)
- return root;
- if (end > root->end)
+ if (end < start || start < root->start || end > root->end)
return root;
p = &root->child;
for (;;) {
@@ -172,9 +168,70 @@ static struct resource * __request_resource(struct resource *root, struct resour
return NULL;
}
p = &tmp->sibling;
- if (tmp->end < start)
- continue;
- return tmp;
+ if (tmp->end >= start)
+ return tmp;
+ }
+}
+
+static inline int check_overlap(struct resource *tmp,
+ resource_size_t start, resource_size_t end)
+{
+ return (tmp->start <= end && tmp->end >= start);
+}
+
+/*
+ * relocate the old resource, to the new position. Return error and do nothing
+ * if the new location conflicts with any other resource.
+ */
+static int re_request_resource(struct resource *root,
+ struct resource *new, struct resource *old)
+{
+ resource_size_t start = new->start;
+ resource_size_t end = new->end;
+ struct resource *tmp = NULL, *prev, **p, **p_old = NULL;
+
+ if (end < start || start < root->start || end > root->end)
+ return -EBUSY;
+ p = &root->child;
+ for (;;) {
+ if ( *p == old ) p_old = p;
+ prev = tmp;
+ tmp = *p;
+
+ /* check for overlaps */
+ if (tmp && check_overlap(tmp, start, end)) {
+ if (tmp != old)
+ return -EBUSY;
+ if (tmp->sibling && check_overlap(tmp->sibling, start, end))
+ return -EBUSY;
+ old->start = start;
+ old->end = end;
+ return 0;
+ }
+
+ if (!tmp || tmp->start > end ) {
+ if (prev == old || tmp == old) {
+ old->start = start;
+ old->end = end;
+ return 0;
+ }
+
+ if (!p_old) {
+ p_old = p;
+ while ( *p_old && old != (*p_old)->sibling )
+ p_old = &(*p_old)->sibling;
+ BUG_ON(!*p_old);
+ }
+
+ /* relocate old */
+ old->start = start;
+ old->end = end;
+ *p_old = old->sibling;
+ old->sibling = tmp;
+ *p = old;
+ return 0;
+ }
+ p = &tmp->sibling;
}
}
@@ -471,7 +528,6 @@ int reallocate_resource(struct resource *root, struct resource *old,
{
int err=0;
struct resource new = *old;
- struct resource *conflict;
write_lock(&resource_lock);
@@ -493,10 +549,7 @@ int reallocate_resource(struct resource *root, struct resource *old,
old->start = new.start;
old->end = new.end;
} else {
- __release_resource(old);
- *old = new;
- conflict = __request_resource(root, old);
- BUG_ON(conflict);
+ err = re_request_resource(root, &new, old);
}
out:
write_unlock(&resource_lock);
--
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