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* [PATCH 1/3] perfcounter: create new chain_for_each_child() iterator
@ 2009-07-02 15:58 Frederic Weisbecker
  2009-07-02 15:58 ` [PATCH 2/3] perfcounter: bring new OPT_CALLBACK_DEFAULT option Frederic Weisbecker
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Frederic Weisbecker @ 2009-07-02 15:58 UTC (permalink / raw)
  To: Ingo Molnar
  Cc: LKML, Peter Zijlstra, Mike Galbraith, Paul Mackerras,
	Anton Blanchard, Arnaldo Carvalho de Melo, Frederic Weisbecker

Iterating through children of a node in the callchain tree shows
something that may be quite confusing at a first glance. The head
is the children field of the parent and the list nodes are in the
brothers field of the children.

This is because the childs are linked to the parent as a list of
"brothers" using the "children" list of the parent as a head:

 ---------------
| Parent (head) |-------------------------------------
 ---------------                                      |
    |                                                 |
 children                                             |
    |                                                 |
 -----------               -----------                |
| 1st child |---brother---| 2nd child |---brother-----
 -----------               -----------

This makes the following strange pattern often occuring:

list_for_each_entry(child, &parent->children, brothers) {
       // do something with children
}

Abstract it to chain_for_each_child() to factorize and simplify
this pattern.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 tools/perf/util/callchain.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 3dceabd..3c4a91f 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -16,6 +16,9 @@
 
 #include "callchain.h"
 
+#define chain_for_each_child(child, parent)	\
+	list_for_each_entry(child, &parent->children, brothers)
+
 
 static void
 rb_insert_callchain(struct rb_root *root, struct callchain_node *chain)
@@ -46,7 +49,7 @@ void sort_chain_to_rbtree(struct rb_root *rb_root, struct callchain_node *node)
 {
 	struct callchain_node *child;
 
-	list_for_each_entry(child, &node->children, brothers)
+	chain_for_each_child(child, node)
 		sort_chain_to_rbtree(rb_root, child);
 
 	if (node->hit)
@@ -77,7 +80,7 @@ create_child(struct callchain_node *parent, bool inherit_children)
 		list_splice(&parent->children, &new->children);
 		INIT_LIST_HEAD(&parent->children);
 
-		list_for_each_entry(next, &new->children, brothers)
+		chain_for_each_child(next, new)
 			next->parent = new;
 	}
 	list_add_tail(&new->brothers, &parent->children);
@@ -173,7 +176,7 @@ __append_chain_children(struct callchain_node *root, struct ip_callchain *chain,
 	struct callchain_node *rnode;
 
 	/* lookup in childrens */
-	list_for_each_entry(rnode, &root->children, brothers) {
+	chain_for_each_child(rnode, root) {
 		unsigned int ret = __append_chain(rnode, chain, start, syms);
 
 		if (!ret)
-- 
1.6.2.3


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2009-07-02 15:58 [PATCH 1/3] perfcounter: create new chain_for_each_child() iterator Frederic Weisbecker
2009-07-02 15:58 ` [PATCH 2/3] perfcounter: bring new OPT_CALLBACK_DEFAULT option Frederic Weisbecker
2009-07-02 18:58   ` [tip:perfcounters/urgent] perf_counter tools: Add " tip-bot for Frederic Weisbecker
2009-07-02 15:58 ` [PATCH 3/3] perfcounter: Add support for callchain graph output Frederic Weisbecker
2009-07-02 18:58   ` [tip:perfcounters/urgent] perf report: " tip-bot for Frederic Weisbecker
2009-07-02 18:57 ` [tip:perfcounters/urgent] perf_counter tools: Create new chain_for_each_child() iterator tip-bot for Frederic Weisbecker

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