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Subject[PATCH 06/15] perf, core: PMU specific data for perf task context
Date
From: "Yan, Zheng" <zheng.z.yan@intel.com>

allow allocating PMU specific data for perf task context

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
include/linux/perf_event.h | 5 +++++
kernel/events/core.c | 19 ++++++++++++++++++-
2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 96cb88b..147f9d3 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -252,6 +252,10 @@ struct pmu {
*/
void (*sched_task) (struct perf_event_context *ctx,
bool sched_in);
+ /*
+ * PMU specific data size
+ */
+ size_t task_ctx_size;
};

/**
@@ -496,6 +500,7 @@ struct perf_event_context {
int pin_count;
int nr_cgroups; /* cgroup evts */
int nr_branch_stack; /* branch_stack evt */
+ void *task_ctx_data; /* pmu specific data */
struct rcu_head rcu_head;
};

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c281265..6499dae 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -882,6 +882,15 @@ static void get_ctx(struct perf_event_context *ctx)
WARN_ON(!atomic_inc_not_zero(&ctx->refcount));
}

+static void free_ctx(struct rcu_head *head)
+{
+ struct perf_event_context *ctx;
+
+ ctx = container_of(head, struct perf_event_context, rcu_head);
+ kfree(ctx->task_ctx_data);
+ kfree(ctx);
+}
+
static void put_ctx(struct perf_event_context *ctx)
{
if (atomic_dec_and_test(&ctx->refcount)) {
@@ -889,7 +898,7 @@ static void put_ctx(struct perf_event_context *ctx)
put_ctx(ctx->parent_ctx);
if (ctx->task)
put_task_struct(ctx->task);
- kfree_rcu(ctx, rcu_head);
+ call_rcu(&ctx->rcu_head, free_ctx);
}
}

@@ -3025,6 +3034,14 @@ alloc_perf_context(struct pmu *pmu, struct task_struct *task)
if (!ctx)
return NULL;

+ if (task && pmu->task_ctx_size > 0) {
+ ctx->task_ctx_data = kzalloc(pmu->task_ctx_size, GFP_KERNEL);
+ if (!ctx->task_ctx_data) {
+ kfree(ctx);
+ return NULL;
+ }
+ }
+
__perf_event_init_context(ctx);
if (task) {
ctx->task = task;
--
1.8.1.4


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