167 lines
5.4 KiB
Diff
167 lines
5.4 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Wed, 25 Jan 2017 16:34:27 +0100
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Subject: [PATCH] radix-tree: use local locks
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.7-rt5.tar.xz
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The preload functionality uses per-CPU variables and preempt-disable to
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ensure that it does not switch CPUs during its usage. This patch adds
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local_locks() instead preempt_disable() for the same purpose and to
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remain preemptible on -RT.
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Cc: stable-rt@vger.kernel.org
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Reported-and-debugged-by: Mike Galbraith <efault@gmx.de>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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include/linux/idr.h | 5 +----
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include/linux/radix-tree.h | 7 ++-----
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lib/radix-tree.c | 32 +++++++++++++++++++++++---------
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3 files changed, 26 insertions(+), 18 deletions(-)
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--- a/include/linux/idr.h
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+++ b/include/linux/idr.h
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@@ -158,10 +158,7 @@ static inline bool idr_is_empty(const st
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* Each idr_preload() should be matched with an invocation of this
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* function. See idr_preload() for details.
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*/
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-static inline void idr_preload_end(void)
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-{
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- preempt_enable();
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-}
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+void idr_preload_end(void);
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/**
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* idr_for_each_entry() - Iterate over an IDR's elements of a given type.
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--- a/include/linux/radix-tree.h
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+++ b/include/linux/radix-tree.h
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@@ -330,6 +330,8 @@ unsigned int radix_tree_gang_lookup_slot
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int radix_tree_preload(gfp_t gfp_mask);
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int radix_tree_maybe_preload(gfp_t gfp_mask);
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int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order);
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+void radix_tree_preload_end(void);
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+
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void radix_tree_init(void);
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void *radix_tree_tag_set(struct radix_tree_root *,
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unsigned long index, unsigned int tag);
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@@ -349,11 +351,6 @@ unsigned int radix_tree_gang_lookup_tag_
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unsigned int max_items, unsigned int tag);
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int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag);
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-static inline void radix_tree_preload_end(void)
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-{
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- preempt_enable();
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-}
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-
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int radix_tree_split_preload(unsigned old_order, unsigned new_order, gfp_t);
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int radix_tree_split(struct radix_tree_root *, unsigned long index,
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unsigned new_order);
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--- a/lib/radix-tree.c
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+++ b/lib/radix-tree.c
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@@ -38,7 +38,7 @@
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#include <linux/rcupdate.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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-
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+#include <linux/locallock.h>
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/* Number of nodes in fully populated tree of given height */
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static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
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@@ -87,6 +87,7 @@ struct radix_tree_preload {
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struct radix_tree_node *nodes;
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};
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static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
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+static DEFINE_LOCAL_IRQ_LOCK(radix_tree_preloads_lock);
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static inline struct radix_tree_node *entry_to_node(void *ptr)
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{
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@@ -405,12 +406,13 @@ radix_tree_node_alloc(gfp_t gfp_mask, st
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* succeed in getting a node here (and never reach
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* kmem_cache_alloc)
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*/
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- rtp = this_cpu_ptr(&radix_tree_preloads);
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+ rtp = &get_locked_var(radix_tree_preloads_lock, radix_tree_preloads);
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if (rtp->nr) {
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ret = rtp->nodes;
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rtp->nodes = ret->parent;
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rtp->nr--;
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}
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+ put_locked_var(radix_tree_preloads_lock, radix_tree_preloads);
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/*
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* Update the allocation stack trace as this is more useful
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* for debugging.
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@@ -476,14 +478,14 @@ static __must_check int __radix_tree_pre
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*/
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gfp_mask &= ~__GFP_ACCOUNT;
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- preempt_disable();
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+ local_lock(radix_tree_preloads_lock);
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rtp = this_cpu_ptr(&radix_tree_preloads);
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while (rtp->nr < nr) {
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- preempt_enable();
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+ local_unlock(radix_tree_preloads_lock);
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node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
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if (node == NULL)
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goto out;
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- preempt_disable();
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+ local_lock(radix_tree_preloads_lock);
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rtp = this_cpu_ptr(&radix_tree_preloads);
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if (rtp->nr < nr) {
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node->parent = rtp->nodes;
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@@ -525,7 +527,7 @@ int radix_tree_maybe_preload(gfp_t gfp_m
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if (gfpflags_allow_blocking(gfp_mask))
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return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
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/* Preloading doesn't help anything with this gfp mask, skip it */
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- preempt_disable();
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+ local_lock(radix_tree_preloads_lock);
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return 0;
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}
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EXPORT_SYMBOL(radix_tree_maybe_preload);
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@@ -563,7 +565,7 @@ int radix_tree_maybe_preload_order(gfp_t
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/* Preloading doesn't help anything with this gfp mask, skip it */
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if (!gfpflags_allow_blocking(gfp_mask)) {
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- preempt_disable();
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+ local_lock(radix_tree_preloads_lock);
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return 0;
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}
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@@ -597,6 +599,12 @@ int radix_tree_maybe_preload_order(gfp_t
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return __radix_tree_preload(gfp_mask, nr_nodes);
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}
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+void radix_tree_preload_end(void)
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+{
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+ local_unlock(radix_tree_preloads_lock);
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+}
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+EXPORT_SYMBOL(radix_tree_preload_end);
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+
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static unsigned radix_tree_load_root(const struct radix_tree_root *root,
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struct radix_tree_node **nodep, unsigned long *maxindex)
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{
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@@ -2102,10 +2110,16 @@ EXPORT_SYMBOL(radix_tree_tagged);
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void idr_preload(gfp_t gfp_mask)
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{
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if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE))
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- preempt_disable();
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+ local_lock(radix_tree_preloads_lock);
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}
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EXPORT_SYMBOL(idr_preload);
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+void idr_preload_end(void)
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+{
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+ local_unlock(radix_tree_preloads_lock);
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+}
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+EXPORT_SYMBOL(idr_preload_end);
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+
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/**
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* ida_pre_get - reserve resources for ida allocation
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* @ida: ida handle
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@@ -2122,7 +2136,7 @@ int ida_pre_get(struct ida *ida, gfp_t g
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* to return to the ida_pre_get() step.
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*/
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if (!__radix_tree_preload(gfp, IDA_PRELOAD_SIZE))
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- preempt_enable();
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+ local_unlock(radix_tree_preloads_lock);
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if (!this_cpu_read(ida_bitmap)) {
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struct ida_bitmap *bitmap = kzalloc(sizeof(*bitmap), gfp);
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