linux-kernel - Re: [PATCH v1 1/3] sched/debug: use int type and fix wrong print for rq->nr

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Message-ID: <3ac59e0f-507f-4603-033b-e493c290cf9f@antgroup.com>
Date:   Tue, 25 Apr 2023 20:14:23 +0800
From:   "晏艳(采苓)" <yanyan.yan@...group.com>
To:     linux-kernel@...r.kernel.org
Cc:     "谈鉴锋" <henry.tjf@...group.com>,
        "Tiwei Bie" <tiwei.btw@...group.com>,
        "Ingo Molnar" <mingo@...hat.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Juri Lelli" <juri.lelli@...hat.com>,
        "Vincent Guittot" <vincent.guittot@...aro.org>,
        "Dietmar Eggemann" <dietmar.eggemann@....com>,
        "Steven Rostedt" <rostedt@...dmis.org>,
        "Ben Segall" <bsegall@...gle.com>, "Mel Gorman" <mgorman@...e.de>,
        "Daniel Bristot de Oliveira" <bristot@...hat.com>,
        "Valentin Schneider" <vschneid@...hat.com>
Subject: Re: [PATCH v1 1/3] sched/debug: use int type and fix wrong print for
 rq->nr_uninterruptible


在 2023/4/19 15:46, 晏艳 写道:
>
>
> 在 2023/4/12 11:07, 晏艳(采苓) 写道:
>> commit e6fe3f422be1 ("sched: Make multiple runqueue task counters
>> 32-bit") changed rq->nr_uninterruptible from 'unsigned long'
>> to 'unsigned int', but left the wrong print to
>> /sys/kernel/debug/sched/debug and to the console.
>>
>> For example:
>> Current type is 'unsigned int' and value is fffffff7, and the print
>> will run the sentences,
>> "do {                                    \
>>      if (sizeof(rq->x) == 4)                     \
>>          SEQ_printf(m, "  .%-30s: %ld\n", #x, (long)(rq->x));    \
>>      else                                \
>>          SEQ_printf(m, "  .%-30s: %Ld\n", #x, (long long)(rq->x));\
>> } while (0)"
>>
>> The result will be 4294967287 on 64-bit machines to print (long)(rq->x)
>> while old type 'unsigned long' will print -9.
>>
>> And the other places that use its value will cast to int to return
>> expected output, so we convert its type from 'unsigned int' to int.
>>
>> Signed-off-by: Yan Yan<yanyan.yan@...group.com>
>> ---
>>   kernel/sched/loadavg.c | 2 +-
>>   kernel/sched/sched.h   | 2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
> Ping, any comment?
>
> thanks,
> -Yan Yan

Ping, any comment?

thanks,

-Yan Yan

>> diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
>> index 52c8f8226b0d..b9867495fe8b 100644
>> --- a/kernel/sched/loadavg.c
>> +++ b/kernel/sched/loadavg.c
>> @@ -80,7 +80,7 @@ long calc_load_fold_active(struct rq *this_rq, long adjust)
>>   	long nr_active, delta = 0;
>>   
>>   	nr_active = this_rq->nr_running - adjust;
>> -	nr_active += (int)this_rq->nr_uninterruptible;
>> +	nr_active += this_rq->nr_uninterruptible;
>>   
>>   	if (nr_active != this_rq->calc_load_active) {
>>   		delta = nr_active - this_rq->calc_load_active;
>> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
>> index 060616944d7a..23c643948331 100644
>> --- a/kernel/sched/sched.h
>> +++ b/kernel/sched/sched.h
>> @@ -1006,7 +1006,7 @@ struct rq {
>>   	 * one CPU and if it got migrated afterwards it may decrease
>>   	 * it on another CPU. Always updated under the runqueue lock:
>>   	 */
>> -	unsigned int		nr_uninterruptible;
>> +	int			nr_uninterruptible;
>>   
>>   	struct task_struct __rcu	*curr;
>>   	struct task_struct	*idle;