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Date: Wed, 29 Aug 2018 15:38:52 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 50/52] rcu: Eliminate RCU-barrier use of rsp
Now that there is only one rcu_state structure, there is less point
in maintaining a pointer to it. This commit therefore replaces rsp
with &rcu_state in rcu_barrier_callback(), rcu_barrier_func(), and
_rcu_barrier().
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/rcu/tree.c | 65 +++++++++++++++++++++++------------------------
1 file changed, 32 insertions(+), 33 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 962b75c9722a..e573fb9f0ef8 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3128,32 +3128,31 @@ static void _rcu_barrier_trace(const char *s, int cpu, unsigned long done)
*/
static void rcu_barrier_callback(struct rcu_head *rhp)
{
- struct rcu_state *rsp = &rcu_state;
-
- if (atomic_dec_and_test(&rsp->barrier_cpu_count)) {
- _rcu_barrier_trace(TPS("LastCB"), -1, rsp->barrier_sequence);
- complete(&rsp->barrier_completion);
+ if (atomic_dec_and_test(&rcu_state.barrier_cpu_count)) {
+ _rcu_barrier_trace(TPS("LastCB"), -1,
+ rcu_state.barrier_sequence);
+ complete(&rcu_state.barrier_completion);
} else {
- _rcu_barrier_trace(TPS("CB"), -1, rsp->barrier_sequence);
+ _rcu_barrier_trace(TPS("CB"), -1, rcu_state.barrier_sequence);
}
}
/*
* Called with preemption disabled, and from cross-cpu IRQ context.
*/
-static void rcu_barrier_func(void *type)
+static void rcu_barrier_func(void *unused)
{
- struct rcu_state *rsp = type;
struct rcu_data *rdp = raw_cpu_ptr(&rcu_data);
- _rcu_barrier_trace(TPS("IRQ"), -1, rsp->barrier_sequence);
+ _rcu_barrier_trace(TPS("IRQ"), -1, rcu_state.barrier_sequence);
rdp->barrier_head.func = rcu_barrier_callback;
debug_rcu_head_queue(&rdp->barrier_head);
if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head, 0)) {
- atomic_inc(&rsp->barrier_cpu_count);
+ atomic_inc(&rcu_state.barrier_cpu_count);
} else {
debug_rcu_head_unqueue(&rdp->barrier_head);
- _rcu_barrier_trace(TPS("IRQNQ"), -1, rsp->barrier_sequence);
+ _rcu_barrier_trace(TPS("IRQNQ"), -1,
+ rcu_state.barrier_sequence);
}
}
@@ -3165,25 +3164,25 @@ static void _rcu_barrier(void)
{
int cpu;
struct rcu_data *rdp;
- struct rcu_state *rsp = &rcu_state;
- unsigned long s = rcu_seq_snap(&rsp->barrier_sequence);
+ unsigned long s = rcu_seq_snap(&rcu_state.barrier_sequence);
_rcu_barrier_trace(TPS("Begin"), -1, s);
/* Take mutex to serialize concurrent rcu_barrier() requests. */
- mutex_lock(&rsp->barrier_mutex);
+ mutex_lock(&rcu_state.barrier_mutex);
/* Did someone else do our work for us? */
- if (rcu_seq_done(&rsp->barrier_sequence, s)) {
- _rcu_barrier_trace(TPS("EarlyExit"), -1, rsp->barrier_sequence);
+ if (rcu_seq_done(&rcu_state.barrier_sequence, s)) {
+ _rcu_barrier_trace(TPS("EarlyExit"), -1,
+ rcu_state.barrier_sequence);
smp_mb(); /* caller's subsequent code after above check. */
- mutex_unlock(&rsp->barrier_mutex);
+ mutex_unlock(&rcu_state.barrier_mutex);
return;
}
/* Mark the start of the barrier operation. */
- rcu_seq_start(&rsp->barrier_sequence);
- _rcu_barrier_trace(TPS("Inc1"), -1, rsp->barrier_sequence);
+ rcu_seq_start(&rcu_state.barrier_sequence);
+ _rcu_barrier_trace(TPS("Inc1"), -1, rcu_state.barrier_sequence);
/*
* Initialize the count to one rather than to zero in order to
@@ -3191,8 +3190,8 @@ static void _rcu_barrier(void)
* (or preemption of this task). Exclude CPU-hotplug operations
* to ensure that no offline CPU has callbacks queued.
*/
- init_completion(&rsp->barrier_completion);
- atomic_set(&rsp->barrier_cpu_count, 1);
+ init_completion(&rcu_state.barrier_completion);
+ atomic_set(&rcu_state.barrier_cpu_count, 1);
get_online_cpus();
/*
@@ -3207,22 +3206,22 @@ static void _rcu_barrier(void)
if (rcu_is_nocb_cpu(cpu)) {
if (!rcu_nocb_cpu_needs_barrier(cpu)) {
_rcu_barrier_trace(TPS("OfflineNoCB"), cpu,
- rsp->barrier_sequence);
+ rcu_state.barrier_sequence);
} else {
_rcu_barrier_trace(TPS("OnlineNoCB"), cpu,
- rsp->barrier_sequence);
+ rcu_state.barrier_sequence);
smp_mb__before_atomic();
- atomic_inc(&rsp->barrier_cpu_count);
+ atomic_inc(&rcu_state.barrier_cpu_count);
__call_rcu(&rdp->barrier_head,
rcu_barrier_callback, cpu, 0);
}
} else if (rcu_segcblist_n_cbs(&rdp->cblist)) {
_rcu_barrier_trace(TPS("OnlineQ"), cpu,
- rsp->barrier_sequence);
- smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
+ rcu_state.barrier_sequence);
+ smp_call_function_single(cpu, rcu_barrier_func, NULL, 1);
} else {
_rcu_barrier_trace(TPS("OnlineNQ"), cpu,
- rsp->barrier_sequence);
+ rcu_state.barrier_sequence);
}
}
put_online_cpus();
@@ -3231,18 +3230,18 @@ static void _rcu_barrier(void)
* Now that we have an rcu_barrier_callback() callback on each
* CPU, and thus each counted, remove the initial count.
*/
- if (atomic_dec_and_test(&rsp->barrier_cpu_count))
- complete(&rsp->barrier_completion);
+ if (atomic_dec_and_test(&rcu_state.barrier_cpu_count))
+ complete(&rcu_state.barrier_completion);
/* Wait for all rcu_barrier_callback() callbacks to be invoked. */
- wait_for_completion(&rsp->barrier_completion);
+ wait_for_completion(&rcu_state.barrier_completion);
/* Mark the end of the barrier operation. */
- _rcu_barrier_trace(TPS("Inc2"), -1, rsp->barrier_sequence);
- rcu_seq_end(&rsp->barrier_sequence);
+ _rcu_barrier_trace(TPS("Inc2"), -1, rcu_state.barrier_sequence);
+ rcu_seq_end(&rcu_state.barrier_sequence);
/* Other rcu_barrier() invocations can now safely proceed. */
- mutex_unlock(&rsp->barrier_mutex);
+ mutex_unlock(&rcu_state.barrier_mutex);
}
/**
--
2.17.1
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