From: MAEDA Naoaki <maeda.naoaki@jp.fujitsu.com>
I am testing PCI hot-plug in 2.6.2 kernel, but sometimes a struct resource
tree in kernel/resource.c was broken if multiple hot-plug requests are
issued at the same time.
The reason is lots of drivers call release_region() on hot removal, and
__release_region(), which is invoked by release_region() macro, changes the
tree without holding a writer lock for resource_lock.
I think __release_region() must hold a writer lock as well as
__request_region() does.
A following patch fixes the issue in my environment.
---
kernel/resource.c | 6 ++++++
1 files changed, 6 insertions(+)
diff -puN kernel/resource.c~release_region-race-fix kernel/resource.c
--- 25/kernel/resource.c~release_region-race-fix 2004-02-11 20:57:20.000000000 -0800
+++ 25-akpm/kernel/resource.c 2004-02-11 20:57:20.000000000 -0800
@@ -475,6 +475,8 @@ void __release_region(struct resource *p
p = &parent->child;
end = start + n - 1;
+ write_lock(&resource_lock);
+
for (;;) {
struct resource *res = *p;
@@ -488,11 +490,15 @@ void __release_region(struct resource *p
if (res->start != start || res->end != end)
break;
*p = res->sibling;
+ write_unlock(&resource_lock);
kfree(res);
return;
}
p = &res->sibling;
}
+
+ write_unlock(&resource_lock);
+
printk(KERN_WARNING "Trying to free nonexistent resource <%08lx-%08lx>\n", start, end);
}
_