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>,
Dietmar Eggemann <dietmar.eggemann@arm•com>,
rostedt <rostedt@goodmis•org>, Ben Segall <bsegall@google•com>,
Mel Gorman <mgorman@suse•de>, bristot <bristot@redhat•com>,
Borislav Petkov <bp@alien8•de>, x86 <x86@kernel•org>,
"H. Peter Anvin" <hpa@zytor•com>, Jens Axboe <axboe@kernel•dk>,
Alasdair Kergon <agk@redhat•com>,
Mike Snitzer <snitzer@redhat•com>, dm-devel <dm-devel@redhat•com>,
"David S. Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>, Felipe Balbi <balbi@kernel•org>,
Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
Alexander Viro <viro@zeniv•linux.org.uk>,
Tejun Heo <tj@kernel•org>, Zefan Li <lizefan.x@bytedance•com>,
Johannes Weiner <hannes@cmpxchg•org>,
Jason Wessel <jason.wessel@windriver•com>,
Daniel Thompson <daniel.thompson@linaro•org>,
Douglas Anderson <dianders@chromium•org>, acme <acme@kernel•org>,
Mark Rutland <mark.rutland@arm•com>,
Alexander Shishkin <alexander.shishkin@linux•intel.com>,
Jiri Olsa <jolsa@redhat•com>, Namhyung Kim <namhyung@kernel•org>,
"Rafael J. Wysocki" <rjw@rjwysocki•net>,
Pavel Machek <pavel@ucw•cz>, Will Deacon <will@kernel•org>,
Waiman Long <longman@redhat•com>,
Boqun Feng <boqun.feng@gmail•com>,
Oleg Nesterov <oleg@redhat•com>,
Davidlohr Bueso <dave@stgolabs•net>, paulmck <paulmck@kernel•org>,
Josh Triplett <josh@joshtriplett•org>,
Lai Jiangshan <jiangshanlai@gmail•com>,
"Joel Fernandes, Google" <joel@joelfernandes•org>,
John Stultz <john.stultz@linaro•org>,
Stephen Boyd <sboyd@kernel•org>,
Andrew Morton <akpm@linux-foundation•org>,
Paolo Bonzini <pbonzini@redhat•com>,
linux-kernel <linux-kernel@vger•kernel.org>,
linux-block <linux-block@vger•kernel.org>,
netdev <netdev@vger•kernel.org>,
linux-usb <linux-usb@vger•kernel.org>,
linux-fsdevel <linux-fsdevel@vger•kernel.org>,
cgroups <cgroups@vger•kernel.org>,
kgdb-bugreport <kgdb-bugreport@lists•sourceforge.net>,
linux-perf-users <linux-perf-users@vger•kernel.org>,
linux-pm <linux-pm@vger•kernel.org>, rcu <rcu@vger•kernel.org>,
linux-mm <linux-mm@kvack•org>, KVM list <kvm@vger•kernel.org>
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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