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rcu: Fix outdated rcu_scheduler_active comment 

The comment header for rcu_scheduler_active states that it is used
to optimize synchronize_sched() at early boot.  This is incorrect.
The synchronize_sched() function instead checks the number of online
CPUs.  This commit therefore replaces the comment's synchronize_sched()
with synchronize_rcu(), which really does use rcu_scheduler_active for
this purpose.

Reported-by: Lihao Liang <lihao.liang@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
hifive-unleashed-5.1
Paul E. McKenney 2016-04-08 05:00:03 -07:00
parent af8c34ce6a
commit 0d95092ccb
1 changed files with 1 additions and 1 deletions
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kernel/rcu/tree.c
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@ -130,7 +130,7 @@ int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */
* The rcu_scheduler_active variable transitions from zero to one just
* before the first task is spawned. So when this variable is zero, RCU
* can assume that there is but one task, allowing RCU to (for example)
* optimize synchronize_sched() to a simple barrier(). When this variable
* optimize synchronize_rcu() to a simple barrier(). When this variable
* is one, RCU must actually do all the hard work required to detect real
* grace periods. This variable is also used to suppress boot-time false
* positives from lockdep-RCU error checking.