From cfa6705d89b6562f79c40c249f8d94073c4276e4 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 27 May 2020 22:11:14 +0200 Subject: radix-tree: Use local_lock for protection The radix-tree and idr preload mechanisms use preempt_disable() to protect the complete operation between xxx_preload() and xxx_preload_end(). As the code inside the preempt disabled section acquires regular spinlocks, which are converted to 'sleeping' spinlocks on a PREEMPT_RT kernel and eventually calls into a memory allocator, this conflicts with the RT semantics. Convert it to a local_lock which allows RT kernels to substitute them with a real per CPU lock. On non RT kernels this maps to preempt_disable() as before, but provides also lockdep coverage of the critical region. No functional change. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/20200527201119.1692513-3-bigeasy@linutronix.de --- include/linux/radix-tree.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'include/linux/radix-tree.h') diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 63e62372443a..c2a9f7c90727 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -16,11 +16,20 @@ #include #include #include +#include /* Keep unconverted code working */ #define radix_tree_root xarray #define radix_tree_node xa_node +struct radix_tree_preload { + local_lock_t lock; + unsigned nr; + /* nodes->parent points to next preallocated node */ + struct radix_tree_node *nodes; +}; +DECLARE_PER_CPU(struct radix_tree_preload, radix_tree_preloads); + /* * The bottom two bits of the slot determine how the remaining bits in the * slot are interpreted: @@ -245,7 +254,7 @@ int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag); static inline void radix_tree_preload_end(void) { - preempt_enable(); + local_unlock(&radix_tree_preloads.lock); } void __rcu **idr_get_free(struct radix_tree_root *root, -- cgit v1.2.3-59-g8ed1b