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Commit 4fc5b755 authored by Iulia Manda's avatar Iulia Manda Committed by Paul E. McKenney
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rcu: Protect uses of jiffies_stall field with ACCESS_ONCE()



Some of the uses of the rcu_state structure's ->jiffies_stall field
do not use ACCESS_ONCE(), despite there being unprotected accesses.
This commit therefore uses the ACCESS_ONCE() macro to protect this field.

Signed-off-by: default avatarIulia Manda <iulia.manda21@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 9b67122a
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+6 −6
Original line number Diff line number Diff line
@@ -865,7 +865,7 @@ 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;
}

@@ -904,12 +904,12 @@ 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;
	ACCESS_ONCE(rsp->jiffies_stall) = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
	raw_spin_unlock_irqrestore(&rnp->lock, flags);

	/*
@@ -992,8 +992,8 @@ 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);

@@ -1077,7 +1077,7 @@ 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;
}

/*