[PATCH v2 7/7] perf: Let userspace know if pmu supports address filters

Alexander Shishkin
2016-04-27T15:46:37Z

Export an additional common attribute for PMUs that support address range
filtering to let the perf userspace identify such PMUs in a uniform way.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
kernel/events/core.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 606398b62a..6d07e294a7 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8282,6 +8282,20 @@ static void free_pmu_context(struct pmu *pmu)
out:
mutex_unlock(&pmus_lock);
}
+
+/*
+ * Let userspace know that this PMU supports address range filtering
+ */
+static ssize_t nr_addr_filters_show(struct device *dev,
+ struct device_attribute *attr,
+ char *page)
+{
+ struct pmu *pmu = dev_get_drvdata(dev);
+
+ return snprintf(page, PAGE_SIZE - 1, "%d\n", pmu->nr_addr_filters);
+}
+DEVICE_ATTR_RO(nr_addr_filters);
+
static struct idr pmu_idr;

static ssize_t
@@ -8383,9 +8397,19 @@ static int pmu_dev_alloc(struct pmu *pmu)
if (ret)
goto free_dev;

+ /* for PMUs with address filters, throw in an extra attribute */
+ if (pmu->nr_addr_filters)
+ ret = device_create_file(pmu->dev, &dev_attr_nr_addr_filters);
+
+ if (ret)
+ goto del_dev;
+
out:
return ret;

+del_dev:
+ device_del(pmu->dev);
+
free_dev:
put_device(pmu->dev);
goto out;
@@ -8521,6 +8545,8 @@ void perf_pmu_unregister(struct pmu *pmu)
free_percpu(pmu->pmu_disable_count);
if (pmu->type >= PERF_TYPE_MAX)
idr_remove(&pmu_idr, pmu->type);
+ if (pmu->nr_addr_filters)
+ device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
device_del(pmu->dev);
put_device(pmu->dev);
free_pmu_context(pmu);
--
2.8.0.rc3