Extract the group leader checking code in function sys_perf_event_open()
to create a new function perf_event_group_leader_check().
The subsequent change would add a new function
perf_event_create_group_kernel_counters() which is used to create group
events in kernel space. The function also needs to do same check for group
leader event just like function sys_perf_event_open() does. So extract
the checking code into a separate function and avoid the code
duplication.
Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
kernel/events/core.c | 143 +++++++++++++++++++++++--------------------
1 file changed, 78 insertions(+), 65 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 78ae7b6f90fd..616391158d7c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12324,6 +12324,81 @@ perf_check_permission(struct perf_event_attr *attr, struct task_struct *task)
return is_capable || ptrace_may_access(task, ptrace_mode);
}
+static int perf_event_group_leader_check(struct perf_event *group_leader,
+ struct perf_event *event,
+ struct perf_event_attr *attr,
+ struct perf_event_context *ctx,
+ struct pmu **pmu,
+ int *move_group)
+{
+ if (!group_leader)
+ return 0;
+
+ /*
+ * Do not allow a recursive hierarchy (this new sibling
+ * becoming part of another group-sibling):
+ */
+ if (group_leader->group_leader != group_leader)
+ return -EINVAL;
+
+ /* All events in a group should have the same clock */
+ if (group_leader->clock != event->clock)
+ return -EINVAL;
+
+ /*
+ * Make sure we're both events for the same CPU;
+ * grouping events for different CPUs is broken; since
+ * you can never concurrently schedule them anyhow.
+ */
+ if (group_leader->cpu != event->cpu)
+ return -EINVAL;
+
+ /*
+ * Make sure we're both on the same context; either task or cpu.
+ */
+ if (group_leader->ctx != ctx)
+ return -EINVAL;
+
+ /*
+ * Only a group leader can be exclusive or pinned
+ */
+ if (attr->exclusive || attr->pinned)
+ return -EINVAL;
+
+ if (is_software_event(event) &&
+ !in_software_context(group_leader)) {
+ /*
+ * If the event is a sw event, but the group_leader
+ * is on hw context.
+ *
+ * Allow the addition of software events to hw
+ * groups, this is safe because software events
+ * never fail to schedule.
+ *
+ * Note the comment that goes with struct
+ * perf_event_pmu_context.
+ */
+ *pmu = group_leader->pmu_ctx->pmu;
+ } else if (!is_software_event(event)) {
+ if (is_software_event(group_leader) &&
+ (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
+ /*
+ * In case the group is a pure software group, and we
+ * try to add a hardware event, move the whole group to
+ * the hardware context.
+ */
+ *move_group = 1;
+ }
+
+ /* Don't allow group of multiple hw events from different pmus */
+ if (!in_software_context(group_leader) &&
+ group_leader->pmu_ctx->pmu != *pmu)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
/**
* sys_perf_event_open - open a performance event, associate it to a task/cpu
*
@@ -12518,71 +12593,9 @@ SYSCALL_DEFINE5(perf_event_open,
}
}
- if (group_leader) {
- err = -EINVAL;
-
- /*
- * Do not allow a recursive hierarchy (this new sibling
- * becoming part of another group-sibling):
- */
- if (group_leader->group_leader != group_leader)
- goto err_locked;
-
- /* All events in a group should have the same clock */
- if (group_leader->clock != event->clock)
- goto err_locked;
-
- /*
- * Make sure we're both events for the same CPU;
- * grouping events for different CPUs is broken; since
- * you can never concurrently schedule them anyhow.
- */
- if (group_leader->cpu != event->cpu)
- goto err_locked;
-
- /*
- * Make sure we're both on the same context; either task or cpu.
- */
- if (group_leader->ctx != ctx)
- goto err_locked;
-
- /*
- * Only a group leader can be exclusive or pinned
- */
- if (attr.exclusive || attr.pinned)
- goto err_locked;
-
- if (is_software_event(event) &&
- !in_software_context(group_leader)) {
- /*
- * If the event is a sw event, but the group_leader
- * is on hw context.
- *
- * Allow the addition of software events to hw
- * groups, this is safe because software events
- * never fail to schedule.
- *
- * Note the comment that goes with struct
- * perf_event_pmu_context.
- */
- pmu = group_leader->pmu_ctx->pmu;
- } else if (!is_software_event(event)) {
- if (is_software_event(group_leader) &&
- (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
- /*
- * In case the group is a pure software group, and we
- * try to add a hardware event, move the whole group to
- * the hardware context.
- */
- move_group = 1;
- }
-
- /* Don't allow group of multiple hw events from different pmus */
- if (!in_software_context(group_leader) &&
- group_leader->pmu_ctx->pmu != pmu)
- goto err_locked;
- }
- }
+ err = perf_event_group_leader_check(group_leader, event, &attr, ctx, &pmu, &move_group);
+ if (err)
+ goto err_locked;
/*
* Now that we're certain of the pmu; find the pmu_ctx.
--
2.34.1
