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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-10-20 21:06:18 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-11-30 07:01:59 +0100 |
| commit | 2d999e03b7c8305b4385dd20992e4ed3e827177b (patch) | |
| tree | 3402eeb03a6cc7ac8013974983f09e46f5ecd562 /kernel/rcutree.c | |
| parent | rcu,cleanup: simplify the code when cpu is dying (diff) | |
| download | linux-2d999e03b7c8305b4385dd20992e4ed3e827177b.tar.xz linux-2d999e03b7c8305b4385dd20992e4ed3e827177b.zip | |
rcu: update documentation/comments for Lai's adoption patch
Lai's RCU-callback immediate-adoption patch changes the RCU tracing
output, so update tracing.txt. Also update a few comments to clarify
the synchronization design.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 669d7fe049d1..120820ffc657 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1668,7 +1668,9 @@ static void _rcu_barrier(struct rcu_state *rsp, * decrement rcu_barrier_cpu_count -- otherwise the first CPU * might complete its grace period before all of the other CPUs * did their increment, causing this function to return too - * early. + * early. Note that on_each_cpu() disables irqs, which prevents + * any CPUs from coming online or going offline until each online + * CPU has queued its RCU-barrier callback. */ atomic_set(&rcu_barrier_cpu_count, 1); on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); @@ -1797,9 +1799,9 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, case CPU_DYING: case CPU_DYING_FROZEN: /* - * The whole machine is "stopped" except this cpu, so we can - * touch any data without introducing corruption. And we send - * the callbacks to an attribute chosen online cpu. + * The whole machine is "stopped" except this CPU, so we can + * touch any data without introducing corruption. We send the + * dying CPU's callbacks to an arbitrarily chosen online CPU. */ rcu_send_cbs_to_online(&rcu_bh_state); rcu_send_cbs_to_online(&rcu_sched_state); |