Commit-ID: 7be8c56f8f8a58af92f8791c5a09d48e342d7101
Gitweb: https://git.kernel.org/tip/7be8c56f8f8a58af92f8791c5a09d48e342d7101
Author: Boqun Feng <boqun.feng@xxxxxxxxx>
AuthorDate: Wed, 7 Mar 2018 16:49:39 +0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 15 May 2018 10:26:01 -0700
rcu: exp: Fix "must hold exp_mutex" comments for QS reporting functions
Since commit d9a3da0699b2 ("rcu: Add expedited grace-period support
for preemptible RCU"), there are comments for some funtions in
rcu_report_exp_rnp()'s call-chain saying that exp_mutex or its
predecessors needs to be held.
However, exp_mutex and its predecessors were used only to synchronize
between GPs, and it is clear that all variables visited by those functions
are under the protection of rcu_node's ->lock. Moreover, those functions
are currently called without held exp_mutex, and seems that doesn't
introduce any trouble.
So this patch fixes this problem by updating the comments to match the
current code.
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Fixes: d9a3da0699b2 ("rcu: Add expedited grace-period support for preemptible RCU")
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Tested-by: Nicholas Piggin <npiggin@xxxxxxxxx>
---
kernel/rcu/tree_exp.h | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 73e1d3dca5b1..d7622cb85aa7 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -154,7 +154,7 @@ static void __maybe_unused sync_exp_reset_tree(struct rcu_state *rsp)
* for the current expedited grace period. Works only for preemptible
* RCU -- other RCU implementation use other means.
*
- * Caller must hold the rcu_state's exp_mutex.
+ * Caller must hold the specificed rcu_node structure's ->lock
*/
static bool sync_rcu_preempt_exp_done(struct rcu_node *rnp)
{
@@ -170,8 +170,7 @@ static bool sync_rcu_preempt_exp_done(struct rcu_node *rnp)
* recursively up the tree. (Calm down, calm down, we do the recursion
* iteratively!)
*
- * Caller must hold the rcu_state's exp_mutex and the specified rcu_node
- * structure's ->lock.
+ * Caller must hold the specified rcu_node structure's ->lock.
*/
static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
bool wake, unsigned long flags)
@@ -207,8 +206,6 @@ static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
/*
* Report expedited quiescent state for specified node. This is a
* lock-acquisition wrapper function for __rcu_report_exp_rnp().
- *
- * Caller must hold the rcu_state's exp_mutex.
*/
static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
struct rcu_node *rnp, bool wake)
@@ -221,8 +218,7 @@ static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
/*
* Report expedited quiescent state for multiple CPUs, all covered by the
- * specified leaf rcu_node structure. Caller must hold the rcu_state's
- * exp_mutex.
+ * specified leaf rcu_node structure.
*/
static void rcu_report_exp_cpu_mult(struct rcu_state *rsp, struct rcu_node *rnp,
unsigned long mask, bool wake)
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|