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From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 1/3] radix_tree: clean away saw_unset_tag leftovers
Date: Tue, 19 Jul 2011 15:52:52 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LSU.2.00.1107191551340.1593@sister.anvils> (raw)
In-Reply-To: <alpine.LSU.2.00.1107191549540.1593@sister.anvils>

radix_tree_tag_get()'s BUG (when it sees a tag after saw_unset_tag) was
unsafe and removed in 2.6.34, but the pointless saw_unset_tag left behind.

Remove it now, and return 0 as soon as we see unset tag - we already rely
upon the root tag to be correct, returning 0 immediately if it's not set.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
 lib/radix-tree.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- mmotm.orig/lib/radix-tree.c	2011-07-08 18:57:14.810702665 -0700
+++ mmotm/lib/radix-tree.c	2011-07-19 11:11:21.285234139 -0700
@@ -576,7 +576,6 @@ int radix_tree_tag_get(struct radix_tree
 {
 	unsigned int height, shift;
 	struct radix_tree_node *node;
-	int saw_unset_tag = 0;
 
 	/* check the root's tag bit */
 	if (!root_tag_get(root, tag))
@@ -603,15 +602,10 @@ int radix_tree_tag_get(struct radix_tree
 			return 0;
 
 		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
-
-		/*
-		 * This is just a debug check.  Later, we can bale as soon as
-		 * we see an unset tag.
-		 */
 		if (!tag_get(node, tag, offset))
-			saw_unset_tag = 1;
+			return 0;
 		if (height == 1)
-			return !!tag_get(node, tag, offset);
+			return 1;
 		node = rcu_dereference_raw(node->slots[offset]);
 		shift -= RADIX_TREE_MAP_SHIFT;
 		height--;

WARNING: multiple messages have this Message-ID (diff)
From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 1/3] radix_tree: clean away saw_unset_tag leftovers
Date: Tue, 19 Jul 2011 15:52:52 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LSU.2.00.1107191551340.1593@sister.anvils> (raw)
In-Reply-To: <alpine.LSU.2.00.1107191549540.1593@sister.anvils>

radix_tree_tag_get()'s BUG (when it sees a tag after saw_unset_tag) was
unsafe and removed in 2.6.34, but the pointless saw_unset_tag left behind.

Remove it now, and return 0 as soon as we see unset tag - we already rely
upon the root tag to be correct, returning 0 immediately if it's not set.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
 lib/radix-tree.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- mmotm.orig/lib/radix-tree.c	2011-07-08 18:57:14.810702665 -0700
+++ mmotm/lib/radix-tree.c	2011-07-19 11:11:21.285234139 -0700
@@ -576,7 +576,6 @@ int radix_tree_tag_get(struct radix_tree
 {
 	unsigned int height, shift;
 	struct radix_tree_node *node;
-	int saw_unset_tag = 0;
 
 	/* check the root's tag bit */
 	if (!root_tag_get(root, tag))
@@ -603,15 +602,10 @@ int radix_tree_tag_get(struct radix_tree
 			return 0;
 
 		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
-
-		/*
-		 * This is just a debug check.  Later, we can bale as soon as
-		 * we see an unset tag.
-		 */
 		if (!tag_get(node, tag, offset))
-			saw_unset_tag = 1;
+			return 0;
 		if (height == 1)
-			return !!tag_get(node, tag, offset);
+			return 1;
 		node = rcu_dereference_raw(node->slots[offset]);
 		shift -= RADIX_TREE_MAP_SHIFT;
 		height--;

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  reply	other threads:[~2011-07-19 22:53 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-19 22:51 [PATCH 0/3] mm: tmpfs radix_tree swap leftovers Hugh Dickins
2011-07-19 22:51 ` Hugh Dickins
2011-07-19 22:52 ` Hugh Dickins [this message]
2011-07-19 22:52   ` [PATCH 1/3] radix_tree: clean away saw_unset_tag leftovers Hugh Dickins
2011-07-19 22:54 ` [PATCH 2/3] tmpfs radix_tree: locate_item to speed up swapoff Hugh Dickins
2011-07-19 22:54   ` Hugh Dickins
2011-07-27 23:28   ` Andrew Morton
2011-07-27 23:28     ` Andrew Morton
2011-07-28  1:54     ` Hugh Dickins
2011-07-28  1:54       ` Hugh Dickins
2011-07-28  9:26       ` Hugh Dickins
2011-07-28  9:26         ` Hugh Dickins
2011-07-19 22:56 ` [PATCH 3/3] mm: clarify the radix_tree exceptional cases Hugh Dickins
2011-07-19 22:56   ` Hugh Dickins

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