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From:   "Uladzislau Rezki (Sony)" <urezki@gmail.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Michel Lespinasse <walken@google.com>
Cc:     linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Roman Gushchin <guro@fb.com>,
        Uladzislau Rezki <urezki@gmail.com>,
        Hillf Danton <hdanton@sina.com>,
        Michal Hocko <mhocko@suse.com>,
        Matthew Wilcox <willy@infradead.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 1/2] augmented rbtree: use max3() in the *_compute_max() function
Date:   Sun, 11 Aug 2019 20:46:12 +0200
Message-Id: <20190811184613.20463-2-urezki@gmail.com>
In-Reply-To: <20190811184613.20463-1-urezki@gmail.com>
References: <20190811184613.20463-1-urezki@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Recently there was introduced RB_DECLARE_CALLBACKS_MAX template.
One of the callback, to be more specific *_compute_max(), calculates
a maximum scalar value of node against its left/right sub-tree.

To simplify the code and improve readability we can switch and
make use of max3() macro that makes the code more transparent.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
 include/linux/rbtree_augmented.h       | 40 +++++++++++++++++-----------------
 tools/include/linux/rbtree_augmented.h | 40 +++++++++++++++++-----------------
 2 files changed, 40 insertions(+), 40 deletions(-)

diff --git a/include/linux/rbtree_augmented.h b/include/linux/rbtree_augmented.h
index fdd421b8d9ae..fb29d6627646 100644
--- a/include/linux/rbtree_augmented.h
+++ b/include/linux/rbtree_augmented.h
@@ -119,26 +119,26 @@ RBSTATIC const struct rb_augment_callbacks RBNAME = {			\
 
 #define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD,	      \
 				 RBTYPE, RBAUGMENTED, RBCOMPUTE)	      \
-static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit)	      \
-{									      \
-	RBSTRUCT *child;						      \
-	RBTYPE max = RBCOMPUTE(node);					      \
-	if (node->RBFIELD.rb_left) {					      \
-		child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD);   \
-		if (child->RBAUGMENTED > max)				      \
-			max = child->RBAUGMENTED;			      \
-	}								      \
-	if (node->RBFIELD.rb_right) {					      \
-		child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD);  \
-		if (child->RBAUGMENTED > max)				      \
-			max = child->RBAUGMENTED;			      \
-	}								      \
-	if (exit && node->RBAUGMENTED == max)				      \
-		return true;						      \
-	node->RBAUGMENTED = max;					      \
-	return false;							      \
-}									      \
-RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,					      \
+static inline RBTYPE RBNAME ## _get_max(struct rb_node *node)		    \
+{									    \
+	RBSTRUCT *tmp;							    \
+									    \
+	tmp = rb_entry_safe(node, RBSTRUCT, RBFIELD);			    \
+	return tmp ? tmp->RBAUGMENTED : 0;				    \
+}									    \
+									    \
+static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit)	    \
+{									    \
+	RBTYPE max = max3(RBCOMPUTE(node),				    \
+		RBNAME ## _get_max(node->RBFIELD.rb_left),		    \
+		RBNAME ## _get_max(node->RBFIELD.rb_right));		    \
+									    \
+	if (exit && node->RBAUGMENTED == max)				    \
+		return true;						    \
+	node->RBAUGMENTED = max;					    \
+	return false;							    \
+}									    \
+RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,					    \
 		     RBSTRUCT, RBFIELD, RBAUGMENTED, RBNAME ## _compute_max)
 
 
diff --git a/tools/include/linux/rbtree_augmented.h b/tools/include/linux/rbtree_augmented.h
index 381aa948610d..3b8284479e98 100644
--- a/tools/include/linux/rbtree_augmented.h
+++ b/tools/include/linux/rbtree_augmented.h
@@ -121,26 +121,26 @@ RBSTATIC const struct rb_augment_callbacks RBNAME = {			\
 
 #define RB_DECLARE_CALLBACKS_MAX(RBSTATIC, RBNAME, RBSTRUCT, RBFIELD,	      \
 				 RBTYPE, RBAUGMENTED, RBCOMPUTE)	      \
-static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit)	      \
-{									      \
-	RBSTRUCT *child;						      \
-	RBTYPE max = RBCOMPUTE(node);					      \
-	if (node->RBFIELD.rb_left) {					      \
-		child = rb_entry(node->RBFIELD.rb_left, RBSTRUCT, RBFIELD);   \
-		if (child->RBAUGMENTED > max)				      \
-			max = child->RBAUGMENTED;			      \
-	}								      \
-	if (node->RBFIELD.rb_right) {					      \
-		child = rb_entry(node->RBFIELD.rb_right, RBSTRUCT, RBFIELD);  \
-		if (child->RBAUGMENTED > max)				      \
-			max = child->RBAUGMENTED;			      \
-	}								      \
-	if (exit && node->RBAUGMENTED == max)				      \
-		return true;						      \
-	node->RBAUGMENTED = max;					      \
-	return false;							      \
-}									      \
-RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,					      \
+static inline RBTYPE RBNAME ## _get_max(struct rb_node *node)		    \
+{									    \
+	RBSTRUCT *tmp;							    \
+									    \
+	tmp = rb_entry_safe(node, RBSTRUCT, RBFIELD);			    \
+	return tmp ? tmp->RBAUGMENTED : 0;				    \
+}									    \
+									    \
+static inline bool RBNAME ## _compute_max(RBSTRUCT *node, bool exit)	    \
+{									    \
+	RBTYPE max = max3(RBCOMPUTE(node),				    \
+		RBNAME ## _get_max(node->RBFIELD.rb_left),		    \
+		RBNAME ## _get_max(node->RBFIELD.rb_right));		    \
+									    \
+	if (exit && node->RBAUGMENTED == max)				    \
+		return true;						    \
+	node->RBAUGMENTED = max;					    \
+	return false;							    \
+}									    \
+RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,					    \
 		     RBSTRUCT, RBFIELD, RBAUGMENTED, RBNAME ## _compute_max)
 
 
-- 
2.11.0