Commit 43630c2c authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] Fix __release_region() race

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.
parent b75add94
No related merge requests found
......@@ -475,6 +475,8 @@ void __release_region(struct resource *parent, unsigned long start, unsigned lon
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 *parent, unsigned long start, unsigned lon
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);
}
......
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