From: Sebastian Andrzej Siewior Date: Wed, 25 Jan 2017 16:34:27 +0100 Subject: [PATCH 088/351] radix-tree: use local locks Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=005680192f8aae72026cff0eff54af2ae3cb0b49 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@vger.kernel.org Reported-and-debugged-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior --- include/linux/idr.h | 5 +---- include/linux/radix-tree.h | 7 ++----- lib/radix-tree.c | 32 +++++++++++++++++++++++--------- 3 files changed, 26 insertions(+), 18 deletions(-) diff --git a/include/linux/idr.h b/include/linux/idr.h index b6c6151c7446..81c9df5c04fa 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -169,10 +169,7 @@ static inline bool idr_is_empty(const struct idr *idr) * Each idr_preload() should be matched with an invocation of this * function. See idr_preload() for details. */ -static inline void idr_preload_end(void) -{ - preempt_enable(); -} +void idr_preload_end(void); /** * idr_for_each_entry() - Iterate over an IDR's elements of a given type. diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 34149e8b5f73..affb0fc4c5b6 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -330,6 +330,8 @@ unsigned int radix_tree_gang_lookup_slot(const struct radix_tree_root *, int radix_tree_preload(gfp_t gfp_mask); int radix_tree_maybe_preload(gfp_t gfp_mask); int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order); +void radix_tree_preload_end(void); + void radix_tree_init(void); void *radix_tree_tag_set(struct radix_tree_root *, unsigned long index, unsigned int tag); @@ -349,11 +351,6 @@ unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *, unsigned int max_items, unsigned int tag); int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag); -static inline void radix_tree_preload_end(void) -{ - preempt_enable(); -} - int radix_tree_split_preload(unsigned old_order, unsigned new_order, gfp_t); int radix_tree_split(struct radix_tree_root *, unsigned long index, unsigned new_order); diff --git a/lib/radix-tree.c b/lib/radix-tree.c index e5cab5c4e383..9309e813bc1f 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -38,7 +38,7 @@ #include #include #include - +#include /* Number of nodes in fully populated tree of given height */ static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly; @@ -87,6 +87,7 @@ struct radix_tree_preload { struct radix_tree_node *nodes; }; static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; +static DEFINE_LOCAL_IRQ_LOCK(radix_tree_preloads_lock); static inline struct radix_tree_node *entry_to_node(void *ptr) { @@ -405,12 +406,13 @@ radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent, * succeed in getting a node here (and never reach * kmem_cache_alloc) */ - rtp = this_cpu_ptr(&radix_tree_preloads); + rtp = &get_locked_var(radix_tree_preloads_lock, radix_tree_preloads); if (rtp->nr) { ret = rtp->nodes; rtp->nodes = ret->parent; rtp->nr--; } + put_locked_var(radix_tree_preloads_lock, radix_tree_preloads); /* * Update the allocation stack trace as this is more useful * for debugging. @@ -476,14 +478,14 @@ static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr) */ gfp_mask &= ~__GFP_ACCOUNT; - preempt_disable(); + local_lock(radix_tree_preloads_lock); rtp = this_cpu_ptr(&radix_tree_preloads); while (rtp->nr < nr) { - 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 = this_cpu_ptr(&radix_tree_preloads); if (rtp->nr < nr) { node->parent = rtp->nodes; @@ -525,7 +527,7 @@ int radix_tree_maybe_preload(gfp_t gfp_mask) if (gfpflags_allow_blocking(gfp_mask)) return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE); /* 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); @@ -563,7 +565,7 @@ int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order) /* Preloading doesn't help anything with this gfp mask, skip it */ if (!gfpflags_allow_blocking(gfp_mask)) { - preempt_disable(); + local_lock(radix_tree_preloads_lock); return 0; } @@ -597,6 +599,12 @@ int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order) return __radix_tree_preload(gfp_mask, nr_nodes); } +void radix_tree_preload_end(void) +{ + local_unlock(radix_tree_preloads_lock); +} +EXPORT_SYMBOL(radix_tree_preload_end); + static unsigned radix_tree_load_root(const struct radix_tree_root *root, struct radix_tree_node **nodep, unsigned long *maxindex) { @@ -2102,10 +2110,16 @@ EXPORT_SYMBOL(radix_tree_tagged); void idr_preload(gfp_t gfp_mask) { if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE)) - preempt_disable(); + local_lock(radix_tree_preloads_lock); } EXPORT_SYMBOL(idr_preload); +void idr_preload_end(void) +{ + local_unlock(radix_tree_preloads_lock); +} +EXPORT_SYMBOL(idr_preload_end); + int ida_pre_get(struct ida *ida, gfp_t gfp) { /* @@ -2114,7 +2128,7 @@ int ida_pre_get(struct ida *ida, gfp_t gfp) * to return to the ida_pre_get() step. */ if (!__radix_tree_preload(gfp, IDA_PRELOAD_SIZE)) - preempt_enable(); + local_unlock(radix_tree_preloads_lock); if (!this_cpu_read(ida_bitmap)) { struct ida_bitmap *bitmap = kzalloc(sizeof(*bitmap), gfp);