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authorBoqun Feng <boqun.feng@gmail.com>2015-12-29 12:18:47 +0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-02-23 19:59:54 -0800
commit67c583a7de3433a971983490b37ad2bff3c55463 (patch)
treeb6d5123664992047b393594cff856de006fb86b4 /kernel/rcu/tree.c
parentad315455d396a1cbcb2f9fdd687b7e1b26b789e7 (diff)
downloadlinux-sh-67c583a7de3433a971983490b37ad2bff3c55463.tar.gz
RCU: Privatize rcu_node::lock
In patch: "rcu: Add transitivity to remaining rcu_node ->lock acquisitions" All locking operations on rcu_node::lock are replaced with the wrappers because of the need of transitivity, which indicates we should never write code using LOCK primitives alone(i.e. without a proper barrier following) on rcu_node::lock outside those wrappers. We could detect this kind of misuses on rcu_node::lock in the future by adding __private modifier on rcu_node::lock. To privatize rcu_node::lock, unlock wrappers are also needed. Replacing spinlock unlocks with these wrappers not only privatizes rcu_node::lock but also makes it easier to figure out critical sections of rcu_node. This patch adds __private modifier to rcu_node::lock and makes every access to it wrapped by ACCESS_PRIVATE(). Besides, unlock wrappers are added and raw_spin_unlock(&rnp->lock) and its friends are replaced with those wrappers. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree.c')
-rw-r--r--kernel/rcu/tree.c103
1 files changed, 52 insertions, 51 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 1e44fce73839..d5a6d2f0cbf4 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1245,7 +1245,7 @@ static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
if (rnp->qsmask & (1UL << cpu))
dump_cpu_task(rnp->grplo + cpu);
}
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
}
@@ -1265,12 +1265,12 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
raw_spin_lock_irqsave_rcu_node(rnp, flags);
delta = jiffies - READ_ONCE(rsp->jiffies_stall);
if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
WRITE_ONCE(rsp->jiffies_stall,
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
/*
* OK, time to rat on our buddy...
@@ -1291,7 +1291,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
ndetected++;
}
}
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
print_cpu_stall_info_end();
@@ -1356,7 +1356,7 @@ static void print_cpu_stall(struct rcu_state *rsp)
if (ULONG_CMP_GE(jiffies, READ_ONCE(rsp->jiffies_stall)))
WRITE_ONCE(rsp->jiffies_stall,
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
/*
* Attempt to revive the RCU machinery by forcing a context switch.
@@ -1594,7 +1594,7 @@ rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp,
}
unlock_out:
if (rnp != rnp_root)
- raw_spin_unlock(&rnp_root->lock);
+ raw_spin_unlock_rcu_node(rnp_root);
out:
if (c_out != NULL)
*c_out = c;
@@ -1814,7 +1814,7 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
return;
}
needwake = __note_gp_changes(rsp, rnp, rdp);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
if (needwake)
rcu_gp_kthread_wake(rsp);
}
@@ -1839,7 +1839,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
raw_spin_lock_irq_rcu_node(rnp);
if (!READ_ONCE(rsp->gp_flags)) {
/* Spurious wakeup, tell caller to go back to sleep. */
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
return false;
}
WRITE_ONCE(rsp->gp_flags, 0); /* Clear all flags: New grace period. */
@@ -1849,7 +1849,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
* Grace period already in progress, don't start another.
* Not supposed to be able to happen.
*/
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
return false;
}
@@ -1858,7 +1858,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
/* Record GP times before starting GP, hence smp_store_release(). */
smp_store_release(&rsp->gpnum, rsp->gpnum + 1);
trace_rcu_grace_period(rsp->name, rsp->gpnum, TPS("start"));
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
/*
* Apply per-leaf buffered online and offline operations to the
@@ -1872,7 +1872,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
if (rnp->qsmaskinit == rnp->qsmaskinitnext &&
!rnp->wait_blkd_tasks) {
/* Nothing to do on this leaf rcu_node structure. */
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
continue;
}
@@ -1906,7 +1906,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
rcu_cleanup_dead_rnp(rnp);
}
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
}
/*
@@ -1937,7 +1937,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
trace_rcu_grace_period_init(rsp->name, rnp->gpnum,
rnp->level, rnp->grplo,
rnp->grphi, rnp->qsmask);
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
cond_resched_rcu_qs();
WRITE_ONCE(rsp->gp_activity, jiffies);
}
@@ -1995,7 +1995,7 @@ static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time)
raw_spin_lock_irq_rcu_node(rnp);
WRITE_ONCE(rsp->gp_flags,
READ_ONCE(rsp->gp_flags) & ~RCU_GP_FLAG_FQS);
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
}
}
@@ -2024,7 +2024,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
* safe for us to drop the lock in order to mark the grace
* period as completed in all of the rcu_node structures.
*/
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
/*
* Propagate new ->completed value to rcu_node structures so
@@ -2045,7 +2045,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
needgp = __note_gp_changes(rsp, rnp, rdp) || needgp;
/* smp_mb() provided by prior unlock-lock pair. */
nocb += rcu_future_gp_cleanup(rsp, rnp);
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
cond_resched_rcu_qs();
WRITE_ONCE(rsp->gp_activity, jiffies);
rcu_gp_slow(rsp, gp_cleanup_delay);
@@ -2067,7 +2067,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
READ_ONCE(rsp->gpnum),
TPS("newreq"));
}
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irq_rcu_node(rnp);
}
/*
@@ -2246,7 +2246,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
{
WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
- raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);
rcu_gp_kthread_wake(rsp);
}
@@ -2276,7 +2276,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
* Our bit has already been cleared, or the
* relevant grace period is already over, so done.
*/
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */
@@ -2288,7 +2288,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {
/* Other bits still set at this level, so done. */
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
mask = rnp->grpmask;
@@ -2298,7 +2298,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
break;
}
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
rnp_c = rnp;
rnp = rnp->parent;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
@@ -2330,7 +2330,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_state *rsp,
if (rcu_state_p == &rcu_sched_state || rsp != rcu_state_p ||
rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return; /* Still need more quiescent states! */
}
@@ -2347,7 +2347,7 @@ static void rcu_report_unblock_qs_rnp(struct rcu_state *rsp,
/* Report up the rest of the hierarchy, tracking current ->gpnum. */
gps = rnp->gpnum;
mask = rnp->grpmask;
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
raw_spin_lock_rcu_node(rnp_p); /* irqs already disabled. */
rcu_report_qs_rnp(mask, rsp, rnp_p, gps, flags);
}
@@ -2384,12 +2384,12 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
*/
rdp->cpu_no_qs.b.norm = true; /* need qs for new gp. */
rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
mask = rdp->grpmask;
if ((rnp->qsmask & mask) == 0) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
} else {
rdp->core_needs_qs = false;
@@ -2600,10 +2600,11 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
rnp->qsmaskinit &= ~mask;
rnp->qsmask &= ~mask;
if (rnp->qsmaskinit) {
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock_rcu_node(rnp);
+ /* irqs remain disabled. */
return;
}
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
}
}
@@ -2626,7 +2627,7 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
mask = rdp->grpmask;
raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
rnp->qsmaskinitnext &= ~mask;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
/*
@@ -2860,7 +2861,7 @@ static void force_qs_rnp(struct rcu_state *rsp,
rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags);
} else {
/* Nothing to do here, so just drop the lock. */
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
}
}
@@ -2896,11 +2897,11 @@ static void force_quiescent_state(struct rcu_state *rsp)
raw_spin_unlock(&rnp_old->fqslock);
if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
rsp->n_force_qs_lh++;
- raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);
return; /* Someone beat us to it. */
}
WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
- raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);
rcu_gp_kthread_wake(rsp);
}
@@ -2926,7 +2927,7 @@ __rcu_process_callbacks(struct rcu_state *rsp)
if (cpu_needs_another_gp(rsp, rdp)) {
raw_spin_lock_rcu_node(rcu_get_root(rsp)); /* irqs disabled. */
needwake = rcu_start_gp(rsp);
- raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);
if (needwake)
rcu_gp_kthread_wake(rsp);
} else {
@@ -3017,7 +3018,7 @@ static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp,
raw_spin_lock_rcu_node(rnp_root);
needwake = rcu_start_gp(rsp);
- raw_spin_unlock(&rnp_root->lock);
+ raw_spin_unlock_rcu_node(rnp_root);
if (needwake)
rcu_gp_kthread_wake(rsp);
} else {
@@ -3437,14 +3438,14 @@ static void sync_exp_reset_tree_hotplug(struct rcu_state *rsp)
rcu_for_each_leaf_node(rsp, rnp) {
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->expmaskinit == rnp->expmaskinitnext) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
continue; /* No new CPUs, nothing to do. */
}
/* Update this node's mask, track old value for propagation. */
oldmask = rnp->expmaskinit;
rnp->expmaskinit = rnp->expmaskinitnext;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
/* If was already nonzero, nothing to propagate. */
if (oldmask)
@@ -3459,7 +3460,7 @@ static void sync_exp_reset_tree_hotplug(struct rcu_state *rsp)
if (rnp_up->expmaskinit)
done = true;
rnp_up->expmaskinit |= mask;
- raw_spin_unlock_irqrestore(&rnp_up->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp_up, flags);
if (done)
break;
mask = rnp_up->grpmask;
@@ -3482,7 +3483,7 @@ static void __maybe_unused sync_exp_reset_tree(struct rcu_state *rsp)
raw_spin_lock_irqsave_rcu_node(rnp, flags);
WARN_ON_ONCE(rnp->expmask);
rnp->expmask = rnp->expmaskinit;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
}
@@ -3523,11 +3524,11 @@ static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
if (!rnp->expmask)
rcu_initiate_boost(rnp, flags);
else
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
break;
}
if (rnp->parent == NULL) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
if (wake) {
smp_mb(); /* EGP done before wake_up(). */
wake_up(&rsp->expedited_wq);
@@ -3535,7 +3536,7 @@ static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
break;
}
mask = rnp->grpmask;
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
+ raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled */
rnp = rnp->parent;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled */
WARN_ON_ONCE(!(rnp->expmask & mask));
@@ -3570,7 +3571,7 @@ static void rcu_report_exp_cpu_mult(struct rcu_state *rsp, struct rcu_node *rnp,
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (!(rnp->expmask & mask)) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
rnp->expmask &= ~mask;
@@ -3731,7 +3732,7 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
*/
if (rcu_preempt_has_tasks(rnp))
rnp->exp_tasks = rnp->blkd_tasks.next;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
/* IPI the remaining CPUs for expedited quiescent state. */
mask = 1;
@@ -3748,7 +3749,7 @@ retry_ipi:
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (cpu_online(cpu) &&
(rnp->expmask & mask)) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
schedule_timeout_uninterruptible(1);
if (cpu_online(cpu) &&
(rnp->expmask & mask))
@@ -3757,7 +3758,7 @@ retry_ipi:
}
if (!(rnp->expmask & mask))
mask_ofl_ipi &= ~mask;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
/* Report quiescent states for those that went offline. */
mask_ofl_test |= mask_ofl_ipi;
@@ -4164,7 +4165,7 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
return;
raw_spin_lock_rcu_node(rnp); /* Interrupts already disabled. */
rnp->qsmaskinit |= mask;
- raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */
+ raw_spin_unlock_rcu_node(rnp); /* Interrupts remain disabled. */
}
}
@@ -4188,7 +4189,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->rsp = rsp;
mutex_init(&rdp->exp_funnel_mutex);
rcu_boot_init_nocb_percpu_data(rdp);
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
/*
@@ -4216,7 +4217,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rcu_sysidle_init_percpu_data(rdp->dynticks);
atomic_set(&rdp->dynticks->dynticks,
(atomic_read(&rdp->dynticks->dynticks) & ~0x1) + 1);
- raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
/*
* Add CPU to leaf rcu_node pending-online bitmask. Any needed
@@ -4237,7 +4238,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->rcu_qs_ctr_snap = per_cpu(rcu_qs_ctr, cpu);
rdp->core_needs_qs = false;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
static void rcu_prepare_cpu(int cpu)
@@ -4359,7 +4360,7 @@ static int __init rcu_spawn_gp_kthread(void)
sp.sched_priority = kthread_prio;
sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
}
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
wake_up_process(t);
}
rcu_spawn_nocb_kthreads();
@@ -4450,8 +4451,8 @@ static void __init rcu_init_one(struct rcu_state *rsp)
cpustride *= levelspread[i];
rnp = rsp->level[i];
for (j = 0; j < levelcnt[i]; j++, rnp++) {
- raw_spin_lock_init(&rnp->lock);
- lockdep_set_class_and_name(&rnp->lock,
+ raw_spin_lock_init(&ACCESS_PRIVATE(rnp, lock));
+ lockdep_set_class_and_name(&ACCESS_PRIVATE(rnp, lock),
&rcu_node_class[i], buf[i]);
raw_spin_lock_init(&rnp->fqslock);
lockdep_set_class_and_name(&rnp->fqslock,