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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2020-05-27 23:11:14 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-05-28 11:31:09 +0300 |
| commit | cfa6705d89b6562f79c40c249f8d94073c4276e4 (patch) | |
| tree | 5279a46bfde01387460f5f23756435c7ad8a2a2f /include | |
| parent | 91710728d1725de51d06b40674abf6e860d592c7 (diff) | |
| download | linux-cfa6705d89b6562f79c40c249f8d94073c4276e4.tar.xz | |
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 <bigeasy@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20200527201119.1692513-3-bigeasy@linutronix.de
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/idr.h | 2 | ||||
| -rw-r--r-- | include/linux/radix-tree.h | 11 |
2 files changed, 11 insertions, 2 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h index ac6e946b6767..3ade03e5c7af 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -171,7 +171,7 @@ static inline bool idr_is_empty(const struct idr *idr) */ static inline void idr_preload_end(void) { - preempt_enable(); + local_unlock(&radix_tree_preloads.lock); } /** 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 <linux/spinlock.h> #include <linux/types.h> #include <linux/xarray.h> +#include <linux/local_lock.h> /* 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, |