3.12.70-rt95-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
The preload functionality uses per-CPU variables and preempt-disable to
ensure that it does not switch CPUs during its usage. This patch adds
local_locks() instead preempt_disable() for the same purpose and to
remain preemptible on -RT.
Cc: stable-rt@xxxxxxxxxxxxxxx
Reported-and-debugged-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/linux/radix-tree.h | 12 ++----------
lib/radix-tree.c | 23 ++++++++++++++---------
2 files changed, 16 insertions(+), 19 deletions(-)
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 148ae0fb87ad..c0df4bc0d297 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -227,13 +227,10 @@ 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_preload_end(void);
+
void radix_tree_init(void);
void *radix_tree_tag_set(struct radix_tree_root *root,
unsigned long index, unsigned int tag);
@@ -256,11 +253,6 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag);
unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item);
-static inline void radix_tree_preload_end(void)
-{
- preempt_enable_nort();
-}
-
/**
* struct radix_tree_iter - radix tree iterator state
*
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 980e869e19a8..1236857dfa1f 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -33,7 +33,7 @@
#include <linux/bitops.h>
#include <linux/rcupdate.h>
#include <linux/hardirq.h> /* in_interrupt() */
-
+#include <linux/locallock.h>
#ifdef __KERNEL__
#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
@@ -94,6 +94,7 @@ struct radix_tree_preload {
struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE];
};
static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
+static DEFINE_LOCAL_IRQ_LOCK(radix_tree_preloads_lock);
static inline void *ptr_to_indirect(void *ptr)
{
@@ -221,13 +222,13 @@ radix_tree_node_alloc(struct radix_tree_root *root)
* succeed in getting a node here (and never reach
* kmem_cache_alloc)
*/
- rtp = &get_cpu_var(radix_tree_preloads);
+ rtp = &get_locked_var(radix_tree_preloads_lock, radix_tree_preloads);
if (rtp->nr) {
ret = rtp->nodes[rtp->nr - 1];
rtp->nodes[rtp->nr - 1] = NULL;
rtp->nr--;
}
- put_cpu_var(radix_tree_preloads);
+ put_locked_var(radix_tree_preloads_lock, radix_tree_preloads);
}
if (ret == NULL)
ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
@@ -262,7 +263,6 @@ 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
@@ -278,14 +278,14 @@ static int __radix_tree_preload(gfp_t gfp_mask)
struct radix_tree_node *node;
int ret = -ENOMEM;
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
rtp = &__get_cpu_var(radix_tree_preloads);
while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
- preempt_enable();
+ local_unlock(radix_tree_preloads_lock);
node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
if (node == NULL)
goto out;
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
rtp = &__get_cpu_var(radix_tree_preloads);
if (rtp->nr < ARRAY_SIZE(rtp->nodes))
rtp->nodes[rtp->nr++] = node;
@@ -324,11 +324,16 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
if (gfp_mask & __GFP_WAIT)
return __radix_tree_preload(gfp_mask);
/* Preloading doesn't help anything with this gfp mask, skip it */
- preempt_disable();
+ local_lock(radix_tree_preloads_lock);
return 0;
}
EXPORT_SYMBOL(radix_tree_maybe_preload);
-#endif
+
+void radix_tree_preload_end(void)
+{
+ local_unlock(radix_tree_preloads_lock);
+}
+EXPORT_SYMBOL(radix_tree_preload_end);
/*
* Return the maximum key which can be store into a
--
2.10.2
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