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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: Iulia Manda <iulia.manda21@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Iulia Manda 2014-03-11 15:22:28 +02:00 коммит произвёл Paul E. McKenney
Родитель 9b67122ae3
Коммит 4fc5b75537
1 изменённых файлов: 6 добавлений и 6 удалений
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12
kernel/rcu/tree.c
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@ -865,7 +865,7 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
rsp->gp_start = j; rsp->gp_start = j;
smp_wmb(); /* Record start time before stall time. */ smp_wmb(); /* Record start time before stall time. */
j1 = rcu_jiffies_till_stall_check(); j1 = rcu_jiffies_till_stall_check();
rsp->jiffies_stall = j + j1; ACCESS_ONCE(rsp->jiffies_stall) = j + j1;
rsp->jiffies_resched = j + j1 / 2; 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. */ /* Only let one CPU complain about others per time interval. */
raw_spin_lock_irqsave(&rnp->lock, flags); 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)) { if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags); raw_spin_unlock_irqrestore(&rnp->lock, flags);
return; 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); raw_spin_unlock_irqrestore(&rnp->lock, flags);
/* /*
@ -992,8 +992,8 @@ static void print_cpu_stall(struct rcu_state *rsp)
dump_stack(); dump_stack();
raw_spin_lock_irqsave(&rnp->lock, flags); raw_spin_lock_irqsave(&rnp->lock, flags);
if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) if (ULONG_CMP_GE(jiffies, ACCESS_ONCE(rsp->jiffies_stall)))
rsp->jiffies_stall = jiffies + ACCESS_ONCE(rsp->jiffies_stall) = jiffies +
3 * rcu_jiffies_till_stall_check() + 3; 3 * rcu_jiffies_till_stall_check() + 3;
raw_spin_unlock_irqrestore(&rnp->lock, flags); raw_spin_unlock_irqrestore(&rnp->lock, flags);
@ -1077,7 +1077,7 @@ void rcu_cpu_stall_reset(void)
struct rcu_state *rsp; struct rcu_state *rsp;
for_each_rcu_flavor(rsp) for_each_rcu_flavor(rsp)
rsp->jiffies_stall = jiffies + ULONG_MAX / 2; ACCESS_ONCE(rsp->jiffies_stall) = jiffies + ULONG_MAX / 2;
} }
/* /*