From 9b5580359a844cc88bdfdbbb3a740817ba01526e Mon Sep 17 00:00:00 2001
From: Kieran Bingham <kieran.bingham@linaro.org>
Date: Mon, 23 May 2016 16:25:10 -0700
Subject: [PATCH] scripts/gdb: add documentation example for radix tree

Provide a worked example for utilising the lx_radix_tree_lookup function

Link: http://lkml.kernel.org/r/e786008ac5aec4b84198812805b326d718bdeb4b.1462865983.git.jan.kiszka@siemens.com
Signed-off-by: Kieran Bingham <kieran.bingham@linaro.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 Documentation/gdb-kernel-debugging.txt | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/gdb-kernel-debugging.txt b/Documentation/gdb-kernel-debugging.txt
index 7050ce8794b9..4ab7d43d0754 100644
--- a/Documentation/gdb-kernel-debugging.txt
+++ b/Documentation/gdb-kernel-debugging.txt
@@ -139,6 +139,27 @@ Examples of using the Linux-provided gdb helpers
       start_comm = "swapper/2\000\000\000\000\000\000"
     }
 
+ o Dig into a radix tree data structure, such as the IRQ descriptors:
+    (gdb) print (struct irq_desc)$lx_radix_tree_lookup(irq_desc_tree, 18)
+    $6 = {
+      irq_common_data = {
+        state_use_accessors = 67584,
+        handler_data = 0x0 <__vectors_start>,
+        msi_desc = 0x0 <__vectors_start>,
+        affinity = {{
+            bits = {65535}
+          }}
+      },
+      irq_data = {
+        mask = 0,
+        irq = 18,
+        hwirq = 27,
+        common = 0xee803d80,
+        chip = 0xc0eb0854 <gic_data>,
+        domain = 0xee808000,
+        parent_data = 0x0 <__vectors_start>,
+        chip_data = 0xc0eb0854 <gic_data>
+      } <... trimmed ...>
 
 List of commands and functions
 ------------------------------