[firefly] [PATCH 2/2] kernel: rcu: Fix unprotected use of jiffies_stall in tree.c

[Iulia Manda]

Protect use of jiffies_stall in tree.c and also some warnings from checkpatch.pl.

Signed-off-by: Iulia Manda <iulia.manda21 at gmail.com>
---
 kernel/rcu/tree.c |   24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b3d116c..2090a94 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -195,7 +195,8 @@ void rcu_sched_qs(int cpu)
 	struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu);
 
 	if (rdp->passed_quiesce == 0)
-		trace_rcu_grace_period(TPS("rcu_sched"), rdp->gpnum, TPS("cpuqs"));
+		trace_rcu_grace_period(TPS("rcu_sched"),
+			rdp->gpnum, TPS("cpuqs"));
 	rdp->passed_quiesce = 1;
 }
 
@@ -377,7 +378,8 @@ static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval,
 		struct task_struct *idle __maybe_unused =
 			idle_task(smp_processor_id());
 
-		trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 0);
+		trace_rcu_dyntick(TPS("Error on entry: not idle task"),
+			oldval, 0);
 		ftrace_dump(DUMP_ORIG);
 		WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
 			  current->pid, current->comm,
@@ -767,7 +769,6 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp,
  * This function really isn't for public consumption, but RCU is special in
  * that context switches can allow the state machine to make progress.
  */
-extern void resched_cpu(int cpu);
 
 /*
  * Return true if the specified CPU has passed through a quiescent
@@ -853,7 +854,7 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
 	rsp->gp_start = j;
 	smp_wmb(); /* Record start time before stall time. */
 	j1 = rcu_jiffies_till_stall_check();
-	rsp->jiffies_stall = j + j1;
+	ACCESS_ONCE(rsp->jiffies_stall) = j + j1;
 	rsp->jiffies_resched = j + j1 / 2;
 }
 
@@ -892,12 +893,13 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
 	/* Only let one CPU complain about others per time interval. */
 
 	raw_spin_lock_irqsave(&rnp->lock, flags);
-	delta = jiffies - rsp->jiffies_stall;
+	delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall);
 	if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
 		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		return;
 	}
-	rsp->jiffies_stall = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
+	rsp->jiffies_stall = jiffies +
+		3 * rcu_jiffies_till_stall_check() + 3;
 	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 
 	/*
@@ -953,7 +955,6 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
  * This function really isn't for public consumption, but RCU is special in
  * that context switches can allow the state machine to make progress.
  */
-extern void resched_cpu(int cpu);
 
 static void print_cpu_stall(struct rcu_state *rsp)
 {
@@ -979,8 +980,8 @@ static void print_cpu_stall(struct rcu_state *rsp)
 		dump_stack();
 
 	raw_spin_lock_irqsave(&rnp->lock, flags);
-	if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall))
-		rsp->jiffies_stall = jiffies +
+	if (ULONG_CMP_GE(jiffies, ACCESS_ONCE(rsp->jiffies_stall)))
+		ACCESS_ONCE(rsp->jiffies_stall) = jiffies +
 				     3 * rcu_jiffies_till_stall_check() + 3;
 	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 
@@ -1064,7 +1065,7 @@ void rcu_cpu_stall_reset(void)
 	struct rcu_state *rsp;
 
 	for_each_rcu_flavor(rsp)
-		rsp->jiffies_stall = jiffies + ULONG_MAX / 2;
+		ACCESS_ONCE(rsp->jiffies_stall) = jiffies + ULONG_MAX / 2;
 }
 
 /*
@@ -1293,7 +1294,8 @@ static void rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp,
 	if (!*rdp->nxttail[RCU_WAIT_TAIL])
 		trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccWaitCB"));
 	else
-		trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccReadyCB"));
+		trace_rcu_grace_period(rsp->name, rdp->gpnum,
+			TPS("AccReadyCB"));
 }
 
 /*
-- 
1.7.10.4