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Subject[PATCH 4/6] remove flip_idx_and_wait()
Date
flip and check are the basic steps of gp. call them directly.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
kernel/srcu.c | 35 +++++++++++++++++------------------
1 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/kernel/srcu.c b/kernel/srcu.c
index d5f3450..d101ed5 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -300,23 +300,12 @@ static void wait_idx(struct srcu_struct *sp, int idx, int trycount)
}

/*
- * Flip the readers' index by incrementing ->completed, then wait
- * until there are no more readers using the counters referenced by
- * the old index value. (Recall that the index is the bottom bit
- * of ->completed.)
- *
- * Of course, it is possible that a reader might be delayed for the
- * full duration of flip_idx_and_wait() between fetching the
- * index and incrementing its counter. This possibility is handled
- * by the next __synchronize_srcu() invoking wait_idx() for such readers
- * before starting a new grace period.
+ * Flip the readers' index by incrementing ->completed, then new
+ * readers will use counters referenced on new index value.
*/
-static void flip_idx_and_wait(struct srcu_struct *sp, int trycount)
+static void srcu_flip(struct srcu_struct *sp)
{
- int idx;
-
- idx = sp->completed++ & 0x1;
- wait_idx(sp, idx, trycount);
+ ACCESS_ONCE(sp->completed)++;
}

/*
@@ -362,10 +351,20 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount)

/*
* Now that wait_idx() has waited for the really old readers,
- * invoke flip_idx_and_wait() to flip the counter and wait
- * for current SRCU readers.
+ *
+ * Flip the readers' index by incrementing ->completed, then wait
+ * until there are no more readers using the counters referenced by
+ * the old index value. (Recall that the index is the bottom bit
+ * of ->completed.)
+ *
+ * Of course, it is possible that a reader might be delayed for the
+ * full duration of flip_idx_and_wait() between fetching the
+ * index and incrementing its counter. This possibility is handled
+ * by the next __synchronize_srcu() invoking wait_idx() for such
+ * readers before starting a new grace period.
*/
- flip_idx_and_wait(sp, trycount);
+ srcu_flip(sp);
+ wait_idx(sp, (sp->completed - 1) & 0x1, trycount);

mutex_unlock(&sp->mutex);
}
--
1.7.4.4


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