From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
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Subject: Re: [PATCH 6/6] sched: Change task_struct::state
Date: Wed, 2 Jun 2021 10:06:58 -0400 (EDT) [thread overview]
Message-ID: <896642516.5866.1622642818225.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20210602133040.587042016@infradead.org>
----- On Jun 2, 2021, at 9:12 AM, Peter Zijlstra peterz@infradead.org wrote:
> Change the type and name of task_struct::state. Drop the volatile and
> shrink it to an 'unsigned int'. Rename it in order to find all uses
> such that we can use READ_ONCE/WRITE_ONCE as appropriate.
>
[...]
>
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
[...]
> @@ -1559,7 +1560,8 @@ static int fill_psinfo(struct elf_prpsin
> psinfo->pr_pgrp = task_pgrp_vnr(p);
> psinfo->pr_sid = task_session_vnr(p);
>
> - i = p->state ? ffz(~p->state) + 1 : 0;
> + state = READ_ONCE(p->__state);
> + i = state ? ffz(~state) + 1 : 0;
> psinfo->pr_state = i;
> psinfo->pr_sname = (i > 5) ? '.' : "RSDTZW"[i];
> psinfo->pr_zomb = psinfo->pr_sname == 'Z';
[...]
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -113,13 +113,13 @@ struct task_group;
> __TASK_TRACED | EXIT_DEAD | EXIT_ZOMBIE | \
> TASK_PARKED)
>
> -#define task_is_running(task) (READ_ONCE((task)->state) == TASK_RUNNING)
> +#define task_is_running(task) (READ_ONCE((task)->__state) == TASK_RUNNING)
>
> -#define task_is_traced(task) ((task->state & __TASK_TRACED) != 0)
> +#define task_is_traced(task) ((READ_ONCE(task->__state) & __TASK_TRACED) != 0)
>
> -#define task_is_stopped(task) ((task->state & __TASK_STOPPED) != 0)
> +#define task_is_stopped(task) ((READ_ONCE(task->__state) & __TASK_STOPPED) !=
> 0)
>
> -#define task_is_stopped_or_traced(task) ((task->state & (__TASK_STOPPED |
> __TASK_TRACED)) != 0)
> +#define task_is_stopped_or_traced(task) ((READ_ONCE(task->__state) &
> (__TASK_STOPPED | __TASK_TRACED)) != 0)
>
> #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
>
> @@ -134,14 +134,14 @@ struct task_group;
> do { \
> WARN_ON_ONCE(is_special_task_state(state_value));\
> current->task_state_change = _THIS_IP_; \
> - current->state = (state_value); \
> + WRITE_ONCE(current->__state, (state_value)); \
> } while (0)
Why not introduce set_task_state(p) and get_task_state(p) rather than sprinkle
READ_ONCE() and WRITE_ONCE() all over the kernel ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2021-06-02 14:09 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-02 13:12 [PATCH 0/6] sched: Cleanup task_struct::state Peter Zijlstra
2021-06-02 13:12 ` [PATCH 1/6] sched: Unbreak wakeups Peter Zijlstra
2021-06-02 13:58 ` Greg Kroah-Hartman
2021-06-02 14:47 ` Will Deacon
2021-06-02 19:43 ` Davidlohr Bueso
2021-06-02 13:12 ` [PATCH 2/6] sched: Introduce task_is_running() Peter Zijlstra
2021-06-02 14:59 ` Will Deacon
2021-06-02 16:46 ` Peter Zijlstra
2021-06-02 23:15 ` Davidlohr Bueso
2021-06-02 13:12 ` [PATCH 3/6] sched,perf,kvm: Fix preemption condition Peter Zijlstra
2021-06-02 13:59 ` Mathieu Desnoyers
2021-06-02 14:10 ` Peter Zijlstra
2021-06-02 14:30 ` Mark Rutland
2021-06-02 14:15 ` Mathieu Desnoyers
2021-06-02 14:23 ` Peter Zijlstra
2021-06-02 13:12 ` [PATCH 4/6] sched: Add get_current_state() Peter Zijlstra
2021-06-02 14:01 ` Mathieu Desnoyers
2021-06-02 14:12 ` Peter Zijlstra
2021-06-02 15:02 ` Will Deacon
2021-06-02 13:12 ` [PATCH 5/6] sched,timer: Use __set_current_state() Peter Zijlstra
2021-06-02 15:06 ` Will Deacon
2021-06-02 19:54 ` Davidlohr Bueso
2021-06-03 6:39 ` Peter Zijlstra
2021-06-18 20:42 ` Thomas Gleixner
2021-06-02 13:12 ` [PATCH 6/6] sched: Change task_struct::state Peter Zijlstra
2021-06-02 14:06 ` Mathieu Desnoyers [this message]
2021-06-02 14:20 ` Peter Zijlstra
2021-06-02 15:10 ` Will Deacon
2021-06-07 10:45 ` Daniel Thompson
2021-06-07 11:10 ` Peter Zijlstra
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