Re: [PATCH 6/7] rcu: rename some CONFIG_PREEMPTION to CONFIG_PREEMPT_RCU

[Lai Jiangshan]

On 2019/10/16 11:54 上午, Paul E. McKenney wrote:

On Tue, Oct 15, 2019 at 10:28:48AM +0000, Lai Jiangshan wrote:

CONFIG_PREEMPTION and CONFIG_PREEMPT_RCU are always identical,
but some code depends on CONFIG_PREEMPTION to access to
rcu_preempt functionalitis. This patch changes CONFIG_PREEMPTION
to CONFIG_PREEMPT_RCU in these cases.

Signed-off-by: Lai Jiangshan <jiangshan...@gmail.com>
Signed-off-by: Lai Jiangshan <la...@linux.alibaba.com>

I believe that this does not cause problems with Sebastian's patch
"[PATCH 27/34] rcu: Use CONFIG_PREEMPTION where appropriate", but could
you please check?

I don't know for which commit the patch "[PATCH 27/34] rcu: Use
CONFIG_PREEMPTION where appropriate" should be applied against
after several tries. But I don't think there will be any conflicts
which this patch by "eye" applying.

Thanks,
Lai

                                                        Thanx, Paul

---
  kernel/rcu/tree.c       | 4 ++--
  kernel/rcu/tree_stall.h | 6 +++---
  2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7db5ea06a9ed..81eb64fcf5ab 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1926,7 +1926,7 @@ rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned 
long flags)
        struct rcu_node *rnp_p;

raw_lockdep_assert_held_rcu_node(rnp);

-       if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPTION)) ||
+       if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPT_RCU)) ||
            WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp)) ||
            rnp->qsmask != 0) {
                raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
@@ -2294,7 +2294,7 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp))
                mask = 0;
                raw_spin_lock_irqsave_rcu_node(rnp, flags);
                if (rnp->qsmask == 0) {
-                       if (!IS_ENABLED(CONFIG_PREEMPTION) ||
+                       if (!IS_ENABLED(CONFIG_PREEMPT_RCU) ||
                            rcu_preempt_blocked_readers_cgp(rnp)) {
                                /*
                                 * No point in scanning bits because they
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 0b75426ebb3e..55f9b84790d3 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -163,7 +163,7 @@ static void rcu_iw_handler(struct irq_work *iwp)
  //
  // Printing RCU CPU stall warnings

-#ifdef CONFIG_PREEMPTION

+#ifdef CONFIG_PREEMPT_RCU

/*

   * Dump detailed information for all tasks blocking the current RCU
@@ -215,7 +215,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp)
        return ndetected;
  }

-#else /* #ifdef CONFIG_PREEMPTION */

+#else /* #ifdef CONFIG_PREEMPT_RCU */

/*

   * Because preemptible RCU does not exist, we never have to check for
@@ -233,7 +233,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp)
  {
        return 0;
  }
-#endif /* #else #ifdef CONFIG_PREEMPTION */
+#endif /* #else #ifdef CONFIG_PREEMPT_RCU */

/*

   * Dump stacks of all tasks running on stalled CPUs.  First try using
--
2.20.1