linux-kernel - [PATCH 2/2] drivers: base: power: wakeup.c: Use built-in RCU list checking

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Date:   Wed,  4 Mar 2020 01:12:09 +0530
From:   madhuparnabhowmik10@...il.com
To:     rjw@...ysocki.net, pavel@....cz, len.brown@...el.com,
        gregkh@...uxfoundation.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        joel@...lfernandes.org, frextrite@...il.com,
        linux-kernel-mentees@...ts.linuxfoundation.org, paulmck@...nel.org,
        Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
Subject: [PATCH 2/2] drivers: base: power: wakeup.c: Use built-in RCU list checking

From: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>

Pass cond argument to list_for_each_entry_rcu() to fix the
following false positive lockdep warning and other uses of
list_for_each_entry_rcu() in wakeup.c.
(CONFIG_PROVE_RCU_LIST = y)

[  331.934648] =============================
[  331.934650] WARNING: suspicious RCU usage
[  331.934653] 5.6.0-rc1+ #5 Not tainted
[  331.934655] -----------------------------
[  331.934657] drivers/base/power/wakeup.c:408 RCU-list traversed in non-reader section!!

[  333.025156] =============================
[  333.025161] WARNING: suspicious RCU usage
[  333.025168] 5.6.0-rc1+ #5 Not tainted
[  333.025173] -----------------------------
[  333.025180] drivers/base/power/wakeup.c:424 RCU-list traversed in non-reader section!!

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
---
 drivers/base/power/wakeup.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index 27f3e60608e5..7e33a8d829dc 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -24,6 +24,9 @@ suspend_state_t pm_suspend_target_state;
 #define pm_suspend_target_state	(PM_SUSPEND_ON)
 #endif
 
+#define list_for_each_entry_rcu_locked(pos, head, member) \
+	list_for_each_entry_rcu(pos, head, member, \
+		srcu_read_lock_held(&wakeup_srcu))
 /*
  * If set, the suspend/hibernate code will abort transitions to a sleep state
  * if wakeup events are registered during or immediately before the transition.
@@ -405,7 +408,7 @@ void device_wakeup_arm_wake_irqs(void)
 	int srcuidx;
 
 	srcuidx = srcu_read_lock(&wakeup_srcu);
-	list_for_each_entry_rcu(ws, &wakeup_sources, entry)
+	list_for_each_entry_rcu_locked(ws, &wakeup_sources, entry)
 		dev_pm_arm_wake_irq(ws->wakeirq);
 	srcu_read_unlock(&wakeup_srcu, srcuidx);
 }
@@ -421,7 +424,7 @@ void device_wakeup_disarm_wake_irqs(void)
 	int srcuidx;
 
 	srcuidx = srcu_read_lock(&wakeup_srcu);
-	list_for_each_entry_rcu(ws, &wakeup_sources, entry)
+	list_for_each_entry_rcu_locked(ws, &wakeup_sources, entry)
 		dev_pm_disarm_wake_irq(ws->wakeirq);
 	srcu_read_unlock(&wakeup_srcu, srcuidx);
 }
@@ -874,7 +877,7 @@ void pm_print_active_wakeup_sources(void)
 	struct wakeup_source *last_activity_ws = NULL;
 
 	srcuidx = srcu_read_lock(&wakeup_srcu);
-	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
+	list_for_each_entry_rcu_locked(ws, &wakeup_sources, entry) {
 		if (ws->active) {
 			pm_pr_dbg("active wakeup source: %s\n", ws->name);
 			active = 1;
@@ -1025,7 +1028,7 @@ void pm_wakep_autosleep_enabled(bool set)
 	int srcuidx;
 
 	srcuidx = srcu_read_lock(&wakeup_srcu);
-	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
+	list_for_each_entry_rcu_locked(ws, &wakeup_sources, entry) {
 		spin_lock_irq(&ws->lock);
 		if (ws->autosleep_enabled != set) {
 			ws->autosleep_enabled = set;
@@ -1104,7 +1107,7 @@ static void *wakeup_sources_stats_seq_start(struct seq_file *m,
 	}
 
 	*srcuidx = srcu_read_lock(&wakeup_srcu);
-	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
+	list_for_each_entry_rcu_locked(ws, &wakeup_sources, entry) {
 		if (n-- <= 0)
 			return ws;
 	}
-- 
2.17.1