perf/core: Fix DocBook warnings

Fix the following W=1 kernel build warning(s):

  kernel/events/core.c:143: warning: Function parameter or member 'cpu' not described in 'cpu_function_call'
  kernel/events/core.c:11924: warning: Function parameter or member 'flags' not described in 'sys_perf_event_open'
  kernel/events/core.c:12382: warning: Function parameter or member 'overflow_handler' not described in 'perf_event_create_kernel_counter'
  kernel/events/core.c:12382: warning: Function parameter or member 'context' not described in 'perf_event_create_kernel_counter'
Signed-off-by: Haocheng Xie <xiehaocheng.cn@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210527031947.1801-3-xiehaocheng.cn@gmail.com

kernel/events/core.c

@@ -132,6 +132,7 @@ task_function_call(struct task_struct *p, remote_function_f func, void *info)
 
 /**
  * cpu_function_call - call a function on the cpu
+ * @cpu:	target cpu to queue this function
  * @func:	the function to be called
  * @info:	the function call argument
  *
@@ -11924,6 +11925,7 @@ __perf_event_ctx_lock_double(struct perf_event *group_leader,
  * @pid:		target pid
  * @cpu:		target cpu
  * @group_fd:		group leader event fd
+ * @flags:		perf event open flags
  */
 SYSCALL_DEFINE5(perf_event_open,
 		struct perf_event_attr __user *, attr_uptr,
@@ -12380,6 +12382,8 @@ SYSCALL_DEFINE5(perf_event_open,
  * @attr: attributes of the counter to create
  * @cpu: cpu in which the counter is bound
  * @task: task to profile (NULL for percpu)
+ * @overflow_handler: callback to trigger when we hit the event
+ * @context: context data could be used in overflow_handler callback
  */
 struct perf_event *
 perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,