4.1.38-rt46-rc1 stable review patch. If you have any objection to the inclusion of this patch, let me know.
--- 8< --- 8< --- 8< --- From: Sebastian Andrzej Siewior <[email protected]> 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: [email protected] Reported-and-debugged-by: Mike Galbraith <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> (cherry picked from commit 682d58995008862febd37bbab89e33e38da84cc4) Signed-off-by: Julia Cartwright <[email protected]> --- include/linux/radix-tree.h | 12 ++---------- lib/radix-tree.c | 22 ++++++++++++++-------- 2 files changed, 16 insertions(+), 18 deletions(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 9a80663a1574..e46b414e9e39 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -277,13 +277,10 @@ 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); @@ -306,11 +303,6 @@ 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 19713243e698..e91567dc635f 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -34,6 +34,7 @@ #include <linux/bitops.h> #include <linux/rcupdate.h> #include <linux/preempt_mask.h> /* in_interrupt() */ +#include <linux/locallock.h> /* @@ -68,6 +69,7 @@ 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) { @@ -195,13 +197,13 @@ 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); /* * Update the allocation stack trace as this is more useful * for debugging. @@ -241,7 +243,6 @@ 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 @@ -257,14 +258,14 @@ 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 = this_cpu_ptr(&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 = this_cpu_ptr(&radix_tree_preloads); if (rtp->nr < ARRAY_SIZE(rtp->nodes)) rtp->nodes[rtp->nr++] = node; @@ -303,11 +304,16 @@ 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 -- 2.11.1
