From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Uladzislau Rezki <urezki@gmail.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>, RCU <rcu@vger.kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Andrew Morton <akpm@linux-foundation.org>,
Daniel Axtens <dja@axtens.net>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
Joel Fernandes <joel@joelfernandes.org>,
Michal Hocko <mhocko@suse.com>,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: Re: [PATCH] kprobes: Fix to delay the kprobes jump optimization
Date: Mon, 22 Feb 2021 11:21:04 +0100 [thread overview]
Message-ID: <20210222102104.v3pr7t57hmpwijpi@linutronix.de> (raw)
In-Reply-To: <20210219183336.GA23049@paulmck-ThinkPad-P72>
On 2021-02-19 10:33:36 [-0800], Paul E. McKenney wrote:
> For definiteness, here is the first part of the change, posted earlier.
> The commit log needs to be updated. I will post the change that keeps
> the tick going as a reply to this email.
…
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index 9d71046..ba78e63 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -209,7 +209,7 @@ static inline void invoke_softirq(void)
> if (ksoftirqd_running(local_softirq_pending()))
> return;
>
> - if (!force_irqthreads) {
> + if (!force_irqthreads || !__this_cpu_read(ksoftirqd)) {
> #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
> /*
> * We can safely execute softirq on the current stack if
> @@ -358,8 +358,8 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
>
> pending = local_softirq_pending();
> if (pending) {
> - if (time_before(jiffies, end) && !need_resched() &&
> - --max_restart)
> + if (!__this_cpu_read(ksoftirqd) ||
> + (time_before(jiffies, end) && !need_resched() && --max_restart))
> goto restart;
This is hunk shouldn't be needed. The reason for it is probably that the
following wakeup_softirqd() would avoid further invoke_softirq()
performing the actual softirq work. It would leave early due to
ksoftirqd_running(). Unless I'm wrong, any raise_softirq() invocation
outside of an interrupt would do the same.
I would like PeterZ / tglx to comment on this one. Basically I'm not
sure if it is okay to expect softirqs beeing served and waited on that
early in the boot.
> wakeup_softirqd();
Sebastian
next prev parent reply other threads:[~2021-02-22 10:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-18 14:29 [PATCH] kprobes: Fix to delay the kprobes jump optimization Masami Hiramatsu
2021-02-18 15:15 ` Paul E. McKenney
2021-02-19 8:17 ` Sebastian Andrzej Siewior
2021-02-19 10:49 ` Uladzislau Rezki
2021-02-19 10:57 ` Sebastian Andrzej Siewior
2021-02-19 11:13 ` Uladzislau Rezki
2021-02-19 11:17 ` Sebastian Andrzej Siewior
2021-02-19 11:23 ` Uladzislau Rezki
2021-02-19 11:27 ` Uladzislau Rezki
2021-02-19 18:18 ` Paul E. McKenney
2021-02-19 18:33 ` Paul E. McKenney
2021-02-19 19:34 ` Paul E. McKenney
2021-02-19 20:02 ` Steven Rostedt
2021-02-19 21:22 ` Paul E. McKenney
2021-02-22 10:21 ` Sebastian Andrzej Siewior [this message]
2021-02-22 12:54 ` Uladzislau Rezki
2021-02-22 15:09 ` Paul E. McKenney
2021-02-22 17:16 ` Uladzislau Rezki
2021-02-22 18:16 ` Paul E. McKenney
2021-02-22 19:07 ` Uladzislau Rezki
2021-02-22 21:32 ` Paul E. McKenney
2021-02-19 19:14 ` Steven Rostedt
2021-02-19 19:45 ` Paul E. McKenney
2021-02-19 20:04 ` Paul E. McKenney
2021-02-22 10:04 ` Sebastian Andrzej Siewior
2021-02-19 19:36 ` Steven Rostedt
2021-02-19 19:47 ` Paul E. McKenney
2021-02-19 19:58 ` Steven Rostedt
2021-02-19 20:04 ` Paul E. McKenney
2021-02-22 12:06 ` Masami Hiramatsu
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