2 files changed, 53 insertions, 2 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ccb0c1fdf1b5..8bab0102ac73 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -188,14 +188,22 @@ config FRAME_POINTER
 
 config UNWIND_INFO
         bool "Compile the kernel with frame unwind information"
-        depends on !IA64
-        depends on !MODULES || !(MIPS || PARISC || PPC || SUPERH || V850)
+        depends on !IA64 && !PARISC
+        depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
         help
           If you say Y here the resulting kernel image will be slightly larger
           but not slower, and it will give very useful debugging information.
           If you don't debug the kernel, you can say N, but we may not be able
           to solve problems without frame unwind information or frame pointers.
 
+config STACK_UNWIND
+        bool "Stack unwind support"
+        depends on UNWIND_INFO
+        depends on X86
+        help
+          This enables more precise stack traces, omitting all unrelated
+          occurrences of pointers into kernel code from the dump.
+
 config FORCED_INLINING
         bool "Force gcc to inline functions marked 'inline'"
         depends on DEBUG_KERNEL
diff --git a/lib/idr.c b/lib/idr.c
index de19030a999b..4d096819511a 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -29,6 +29,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #endif
+#include <linux/err.h>
 #include <linux/string.h>
 #include <linux/idr.h>
 
@@ -398,6 +399,48 @@ void *idr_find(struct idr *idp, int id)
 }
 EXPORT_SYMBOL(idr_find);
 
+/**
+ * idr_replace - replace pointer for given id
+ * @idp: idr handle
+ * @ptr: pointer you want associated with the id
+ * @id: lookup key
+ *
+ * Replace the pointer registered with an id and return the old value.
+ * A -ENOENT return indicates that @id was not found.
+ * A -EINVAL return indicates that @id was not within valid constraints.
+ *
+ * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove().
+ */
+void *idr_replace(struct idr *idp, void *ptr, int id)
+{
+        int n;
+        struct idr_layer *p, *old_p;
+
+        n = idp->layers * IDR_BITS;
+        p = idp->top;
+
+        id &= MAX_ID_MASK;
+
+        if (id >= (1 << n))
+                return ERR_PTR(-EINVAL);
+
+        n -= IDR_BITS;
+        while ((n > 0) && p) {
+                p = p->ary[(id >> n) & IDR_MASK];
+                n -= IDR_BITS;
+        }
+
+        n = id & IDR_MASK;
+        if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
+                return ERR_PTR(-ENOENT);
+
+        old_p = p->ary[n];
+        p->ary[n] = ptr;
+
+        return old_p;
+}
+EXPORT_SYMBOL(idr_replace);
+
 static void idr_cache_ctor(void * idr_layer, kmem_cache_t *idr_layer_cache,
                 unsigned long flags)
 {