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rcu: Eliminate RCU-barrier use of rsp

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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@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-07-05 16:26:12 -07:00
parent 67a0edbf3c
commit ec9f5835f7
1 changed files with 32 additions and 33 deletions
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65
kernel/rcu/tree.c
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@ -3129,32 +3129,31 @@ static void _rcu_barrier_trace(const char *s, int cpu, unsigned long done)
*/ */
static void rcu_barrier_callback(struct rcu_head *rhp) static void rcu_barrier_callback(struct rcu_head *rhp)
{ {
struct rcu_state *rsp = &rcu_state; if (atomic_dec_and_test(&rcu_state.barrier_cpu_count)) {
_rcu_barrier_trace(TPS("LastCB"), -1,
if (atomic_dec_and_test(&rsp->barrier_cpu_count)) { rcu_state.barrier_sequence);
_rcu_barrier_trace(TPS("LastCB"), -1, rsp->barrier_sequence); complete(&rcu_state.barrier_completion);
complete(&rsp->barrier_completion);
} else { } 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. * 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); 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; rdp->barrier_head.func = rcu_barrier_callback;
debug_rcu_head_queue(&rdp->barrier_head); debug_rcu_head_queue(&rdp->barrier_head);
if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head, 0)) { if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head, 0)) {
atomic_inc(&rsp->barrier_cpu_count); atomic_inc(&rcu_state.barrier_cpu_count);
} else { } else {
debug_rcu_head_unqueue(&rdp->barrier_head); 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);
} }
} }
@ -3166,25 +3165,25 @@ static void _rcu_barrier(void)
{ {
int cpu; int cpu;
struct rcu_data *rdp; struct rcu_data *rdp;
struct rcu_state *rsp = &rcu_state; unsigned long s = rcu_seq_snap(&rcu_state.barrier_sequence);
unsigned long s = rcu_seq_snap(&rsp->barrier_sequence);
_rcu_barrier_trace(TPS("Begin"), -1, s); _rcu_barrier_trace(TPS("Begin"), -1, s);
/* Take mutex to serialize concurrent rcu_barrier() requests. */ /* 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? */ /* Did someone else do our work for us? */
if (rcu_seq_done(&rsp->barrier_sequence, s)) { if (rcu_seq_done(&rcu_state.barrier_sequence, s)) {
_rcu_barrier_trace(TPS("EarlyExit"), -1, rsp->barrier_sequence); _rcu_barrier_trace(TPS("EarlyExit"), -1,
rcu_state.barrier_sequence);
smp_mb(); /* caller's subsequent code after above check. */ smp_mb(); /* caller's subsequent code after above check. */
mutex_unlock(&rsp->barrier_mutex); mutex_unlock(&rcu_state.barrier_mutex);
return; return;
} }
/* Mark the start of the barrier operation. */ /* Mark the start of the barrier operation. */
rcu_seq_start(&rsp->barrier_sequence); rcu_seq_start(&rcu_state.barrier_sequence);
_rcu_barrier_trace(TPS("Inc1"), -1, rsp->barrier_sequence); _rcu_barrier_trace(TPS("Inc1"), -1, rcu_state.barrier_sequence);
/* /*
* Initialize the count to one rather than to zero in order to * Initialize the count to one rather than to zero in order to
@ -3192,8 +3191,8 @@ static void _rcu_barrier(void)
* (or preemption of this task). Exclude CPU-hotplug operations * (or preemption of this task). Exclude CPU-hotplug operations
* to ensure that no offline CPU has callbacks queued. * to ensure that no offline CPU has callbacks queued.
*/ */
init_completion(&rsp->barrier_completion); init_completion(&rcu_state.barrier_completion);
atomic_set(&rsp->barrier_cpu_count, 1); atomic_set(&rcu_state.barrier_cpu_count, 1);
get_online_cpus(); get_online_cpus();
/* /*
@ -3208,22 +3207,22 @@ static void _rcu_barrier(void)
if (rcu_is_nocb_cpu(cpu)) { if (rcu_is_nocb_cpu(cpu)) {
if (!rcu_nocb_cpu_needs_barrier(cpu)) { if (!rcu_nocb_cpu_needs_barrier(cpu)) {
_rcu_barrier_trace(TPS("OfflineNoCB"), cpu, _rcu_barrier_trace(TPS("OfflineNoCB"), cpu,
rsp->barrier_sequence); rcu_state.barrier_sequence);
} else { } else {
_rcu_barrier_trace(TPS("OnlineNoCB"), cpu, _rcu_barrier_trace(TPS("OnlineNoCB"), cpu,
rsp->barrier_sequence); rcu_state.barrier_sequence);
smp_mb__before_atomic(); smp_mb__before_atomic();
atomic_inc(&rsp->barrier_cpu_count); atomic_inc(&rcu_state.barrier_cpu_count);
__call_rcu(&rdp->barrier_head, __call_rcu(&rdp->barrier_head,
rcu_barrier_callback, cpu, 0); rcu_barrier_callback, cpu, 0);
} }
} else if (rcu_segcblist_n_cbs(&rdp->cblist)) { } else if (rcu_segcblist_n_cbs(&rdp->cblist)) {
_rcu_barrier_trace(TPS("OnlineQ"), cpu, _rcu_barrier_trace(TPS("OnlineQ"), cpu,
rsp->barrier_sequence); rcu_state.barrier_sequence);
smp_call_function_single(cpu, rcu_barrier_func, rsp, 1); smp_call_function_single(cpu, rcu_barrier_func, NULL, 1);
} else { } else {
_rcu_barrier_trace(TPS("OnlineNQ"), cpu, _rcu_barrier_trace(TPS("OnlineNQ"), cpu,
rsp->barrier_sequence); rcu_state.barrier_sequence);
} }
} }
put_online_cpus(); put_online_cpus();
@ -3232,18 +3231,18 @@ static void _rcu_barrier(void)
* Now that we have an rcu_barrier_callback() callback on each * Now that we have an rcu_barrier_callback() callback on each
* CPU, and thus each counted, remove the initial count. * CPU, and thus each counted, remove the initial count.
*/ */
if (atomic_dec_and_test(&rsp->barrier_cpu_count)) if (atomic_dec_and_test(&rcu_state.barrier_cpu_count))
complete(&rsp->barrier_completion); complete(&rcu_state.barrier_completion);
/* Wait for all rcu_barrier_callback() callbacks to be invoked. */ /* 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. */ /* Mark the end of the barrier operation. */
_rcu_barrier_trace(TPS("Inc2"), -1, rsp->barrier_sequence); _rcu_barrier_trace(TPS("Inc2"), -1, rcu_state.barrier_sequence);
rcu_seq_end(&rsp->barrier_sequence); rcu_seq_end(&rcu_state.barrier_sequence);
/* Other rcu_barrier() invocations can now safely proceed. */ /* Other rcu_barrier() invocations can now safely proceed. */
mutex_unlock(&rsp->barrier_mutex); mutex_unlock(&rcu_state.barrier_mutex);
} }
/** /**