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Subject[PATCH 2/6] Don't touch the snap in srcu_readers_active()
Date
srcu_readers_active() is called without the mutex, but it touch the snap.
also achieve better cache locality a little

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
kernel/srcu.c | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/kernel/srcu.c b/kernel/srcu.c
index b6b9ea2..fbe2d5f 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -181,7 +181,14 @@ static bool srcu_readers_active_idx_check(struct srcu_struct *sp, int idx)
*/
static int srcu_readers_active(struct srcu_struct *sp)
{
- return srcu_readers_active_idx(sp, 0) + srcu_readers_active_idx(sp, 1);
+ int cpu;
+ unsigned long sum = 0;
+
+ for_each_possible_cpu(cpu) {
+ sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]);
+ sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]);
+ }
+ return sum & SRCU_REF_MASK;
}

/**
--
1.7.4.4


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