perf: Default PMU ops
Provide default implementations for the pmu txn methods, this
allows us to remove some conditional code.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Michael Cree <mcree@orcon.net.nz>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 5ed0c06..8ef4ba3 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -674,21 +674,14 @@
{
struct perf_event *event, *partial_group = NULL;
struct pmu *pmu = group_event->pmu;
- bool txn = false;
if (group_event->state == PERF_EVENT_STATE_OFF)
return 0;
- /* Check if group transaction availabe */
- if (pmu->start_txn)
- txn = true;
-
- if (txn)
- pmu->start_txn(pmu);
+ pmu->start_txn(pmu);
if (event_sched_in(group_event, cpuctx, ctx)) {
- if (txn)
- pmu->cancel_txn(pmu);
+ pmu->cancel_txn(pmu);
return -EAGAIN;
}
@@ -702,7 +695,7 @@
}
}
- if (!txn || !pmu->commit_txn(pmu))
+ if (!pmu->commit_txn(pmu))
return 0;
group_error:
@@ -717,8 +710,7 @@
}
event_sched_out(group_event, cpuctx, ctx);
- if (txn)
- pmu->cancel_txn(pmu);
+ pmu->cancel_txn(pmu);
return -EAGAIN;
}
@@ -4965,6 +4957,31 @@
static DEFINE_MUTEX(pmus_lock);
static struct srcu_struct pmus_srcu;
+static void perf_pmu_nop_void(struct pmu *pmu)
+{
+}
+
+static int perf_pmu_nop_int(struct pmu *pmu)
+{
+ return 0;
+}
+
+static void perf_pmu_start_txn(struct pmu *pmu)
+{
+ perf_pmu_disable(pmu);
+}
+
+static int perf_pmu_commit_txn(struct pmu *pmu)
+{
+ perf_pmu_enable(pmu);
+ return 0;
+}
+
+static void perf_pmu_cancel_txn(struct pmu *pmu)
+{
+ perf_pmu_enable(pmu);
+}
+
int perf_pmu_register(struct pmu *pmu)
{
int ret;
@@ -4974,6 +4991,29 @@
pmu->pmu_disable_count = alloc_percpu(int);
if (!pmu->pmu_disable_count)
goto unlock;
+
+ if (!pmu->start_txn) {
+ if (pmu->pmu_enable) {
+ /*
+ * If we have pmu_enable/pmu_disable calls, install
+ * transaction stubs that use that to try and batch
+ * hardware accesses.
+ */
+ pmu->start_txn = perf_pmu_start_txn;
+ pmu->commit_txn = perf_pmu_commit_txn;
+ pmu->cancel_txn = perf_pmu_cancel_txn;
+ } else {
+ pmu->start_txn = perf_pmu_nop_void;
+ pmu->commit_txn = perf_pmu_nop_int;
+ pmu->cancel_txn = perf_pmu_nop_void;
+ }
+ }
+
+ if (!pmu->pmu_enable) {
+ pmu->pmu_enable = perf_pmu_nop_void;
+ pmu->pmu_disable = perf_pmu_nop_void;
+ }
+
list_add_rcu(&pmu->entry, &pmus);
ret = 0;
unlock: