From: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
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>,
Steven Rostedt <rostedt@goodmis•org>,
Ben Segall <bsegall@google•com>, Mel Gorman <mgorman@suse•de>,
Daniel Bristot de Oliveira <bristot@redhat•com>,
Borislav Petkov <bp@alien8•de>,
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@redhat•com, "David S. Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>, Felipe Balbi <balbi@kernel•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>,
Arnaldo Carvalho de Melo <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>,
"Paul E. McKenney" <paulmck@kernel•org>,
Josh Triplett <josh@joshtriplett•org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios•com>,
Lai Jiangshan <jiangshanlai@gmail•com>,
Joel Fernandes <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@vger•kernel.org, linux-block@vger•kernel.org,
netdev@vger•kernel.org, linux-usb@vger•kernel.org,
linux-fsdevel@vger•kernel.org, cgroups@vger•kernel.org,
kgdb-bugreport@lists•sourceforge.net,
linux-perf-users@vger•kernel.org, linux-pm@vger•kernel.org,
rcu@vger•kernel.org, linux-mm@kvack•org, kvm@vger•kernel.org
Subject: Re: [PATCH 1/6] sched: Unbreak wakeups
Date: Wed, 2 Jun 2021 15:58:04 +0200 [thread overview]
Message-ID: <YLeObHTKKDGd3pdA@kroah.com> (raw)
In-Reply-To: <20210602133040.271625424@infradead.org>
On Wed, Jun 02, 2021 at 03:12:26PM +0200, Peter Zijlstra wrote:
> Remove broken task->state references and let wake_up_process() DTRT.
>
> The anti-pattern in these patches breaks the ordering of ->state vs
> COND as described in the comment near set_current_state() and can lead
> to missed wakeups:
>
> (OoO load, observes RUNNING)<-.
> for (;;) { |
> t->state = UNINTERRUPTIBLE; |
> smp_mb(); ,-----> ,' (OoO load, observed !COND)
> | |
> | | COND = 1;
> | `- if (t->state != RUNNING)
> | wake_up_process(t); // not done
> if (COND) ---------'
> break;
> schedule(); // forever waiting
> }
> t->state = TASK_RUNNING;
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead•org>
> ---
> drivers/net/ethernet/qualcomm/qca_spi.c | 6 ++----
> drivers/usb/gadget/udc/max3420_udc.c | 15 +++++----------
> drivers/usb/host/max3421-hcd.c | 3 +--
> kernel/softirq.c | 2 +-
> 4 files changed, 9 insertions(+), 17 deletions(-)
For USB stuff:
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation•org>
next prev parent reply other threads:[~2021-06-02 13:58 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 [this message]
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
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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