rt-patches/0073-radix-tree-Make-RT-aware.patch

From 84a7d00ceec75535412e1a1311802fa686246fc7 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 17 Jul 2011 21:33:18 +0200
Subject: [PATCH 073/366] radix-tree: Make RT aware

Disable radix_tree_preload() on -RT. This functions returns with
preemption disabled which may cause high latencies and breaks if the
user tries to grab any locks after invoking it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/radix-tree.h | 7 ++++++-
 lib/radix-tree.c           | 5 ++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 5d5174b..8ddbd6e 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -277,8 +277,13 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
 unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root,
 			void ***results, unsigned long *indices,
 			unsigned long first_index, unsigned int max_items);
+#ifndef CONFIG_PREEMPT_RT_FULL
 int radix_tree_preload(gfp_t gfp_mask);
 int radix_tree_maybe_preload(gfp_t gfp_mask);
+#else
+static inline int radix_tree_preload(gfp_t gm) { return 0; }
+static inline int radix_tree_maybe_preload(gfp_t gfp_mask) { return 0; }
+#endif
 void radix_tree_init(void);
 void *radix_tree_tag_set(struct radix_tree_root *root,
 			unsigned long index, unsigned int tag);
@@ -303,7 +308,7 @@ unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item);
 
 static inline void radix_tree_preload_end(void)
 {
-	preempt_enable();
+	preempt_enable_nort();
 }
 
 /**
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 6b79e90..f27e0bc 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -196,13 +196,14 @@ radix_tree_node_alloc(struct radix_tree_root *root)
 		 * succeed in getting a node here (and never reach
 		 * kmem_cache_alloc)
 		 */
-		rtp = this_cpu_ptr(&radix_tree_preloads);
+		rtp = &get_cpu_var(radix_tree_preloads);
 		if (rtp->nr) {
 			ret = rtp->nodes;
 			rtp->nodes = ret->private_data;
 			ret->private_data = NULL;
 			rtp->nr--;
 		}
+		put_cpu_var(radix_tree_preloads);
 		/*
 		 * Update the allocation stack trace as this is more useful
 		 * for debugging.
@@ -242,6 +243,7 @@ radix_tree_node_free(struct radix_tree_node *node)
 	call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
 }
 
+#ifndef CONFIG_PREEMPT_RT_FULL
 /*
  * Load up this CPU's radix_tree_node buffer with sufficient objects to
  * ensure that the addition of a single element in the tree cannot fail.  On
@@ -310,6 +312,7 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
 	return 0;
 }
 EXPORT_SYMBOL(radix_tree_maybe_preload);
+#endif
 
 /*
  *	Return the maximum key which can be store into a
-- 
1.9.1