Re: [PATCH v2] kernel/events/core: check return value of task_function_call()

[Ingo Molnar <mingo@kernel.org>]

* Li Zhong <floridsleeves@gmail.com> wrote:

> From: lily <floridsleeves@gmail.com>
> 
> Check the return value of task_function_call(), which could be error
> code when the execution fails. We log this on info level.
> 
> Signed-off-by: Li Zhong <floridsleeves@gmail.com>
> ---
>  kernel/events/core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 2621fd24ad26..3848631b009c 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -13520,7 +13520,10 @@ static void perf_cgroup_attach(struct cgroup_taskset *tset)
>  	struct cgroup_subsys_state *css;
>  
>  	cgroup_taskset_for_each(task, css, tset)
> -		task_function_call(task, __perf_cgroup_move, task);
> +		if (!task_function_call(task, __perf_cgroup_move, task)) {
> +			printk(KERN_INFO "perf: this process isn't running!\n");
> +			continue;

If this is a 'should never happen' condition, then this should really be 
WARN_ON_ONCE().

(If it can happen, then polluting the syslog is wrong.)

Thanks,

	Ingo