From: John Ogness <john.ogness@linutronix.de>
To: paulmck@kernel.org, Petr Mladek <pmladek@suse.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com, rostedt@goodmis.org,
Frederic Weisbecker <frederic@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH rcu v2] 4/5] rcu-tasks: Move RCU Tasks self-tests to core_initcall()
Date: Wed, 05 Feb 2025 23:26:41 +0106 [thread overview]
Message-ID: <841pwc11ae.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <efef835a-d2dd-4f03-bb02-c0cf873433e1@paulmck-laptop>
On 2025-02-05, "Paul E. McKenney" <paulmck@kernel.org> wrote:
>> If there is no backlog, pr_flush() returns immediately.
>
> OK, so I don't need to add "if (IS_ENABLED(CONFIG_PREEMPT_RT))" to guard
> it, then?
For !CONFIG_PREEMPT_RT, if there are legacy consoles registered,
pr_flush() will additionally perform a blocking lock on the
console_lock. The kernel is in a clean shutdown path, so it should not
be a risk to block on the console_lock. But the console_lock is one of
the ugly global locks (semaphore, actually) we are working to remove
because sometimes it still causes problems.
@pmladek: What do you think? Should we have a CONFIG_PREEMPT_RT guard,
which would always be safe? Or do you feel comfortable performing a
console_lock() in the shutdown path for !CONFIG_PREEMPT_RT?
John
next prev parent reply other threads:[~2025-02-05 22:20 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-16 20:05 [PATCH rcu 0/5] Miscellaneous fixes Paul E. McKenney
2025-01-16 20:05 ` [PATCH rcu 1/5] rcu: Split rcu_report_exp_cpu_mult() mask parameter and use for tracing Paul E. McKenney
2025-01-16 20:05 ` [PATCH rcu 2/5] rcu: Remove READ_ONCE() for rdp->gpwrap access in __note_gp_changes() Paul E. McKenney
2025-01-16 20:05 ` [PATCH rcu 3/5] rcu: Fix get_state_synchronize_rcu_full() GP-start detection Paul E. McKenney
2025-01-16 20:05 ` [PATCH rcu 4/5] rcu-tasks: Move RCU Tasks self-tests to core_initcall() Paul E. McKenney
2025-01-16 20:05 ` [PATCH rcu 5/5] rcu/nocb: Print segment lengths in show_rcu_nocb_gp_state() Paul E. McKenney
2025-01-30 18:53 ` [PATCH rcu 0/5] Miscellaneous fixes Paul E. McKenney
2025-01-30 18:53 ` [PATCH rcu v2] 1/5] rcu: Split rcu_report_exp_cpu_mult() mask parameter and use for tracing Paul E. McKenney
2025-01-30 18:53 ` [PATCH rcu v2] 2/5] rcu: Remove READ_ONCE() for rdp->gpwrap access in __note_gp_changes() Paul E. McKenney
2025-01-30 18:53 ` [PATCH rcu v2] 3/5] rcu: Fix get_state_synchronize_rcu_full() GP-start detection Paul E. McKenney
2025-01-30 18:53 ` [PATCH rcu v2] 4/5] rcu-tasks: Move RCU Tasks self-tests to core_initcall() Paul E. McKenney
2025-02-04 10:26 ` Sebastian Andrzej Siewior
2025-02-04 11:51 ` Paul E. McKenney
2025-02-04 16:34 ` Sebastian Andrzej Siewior
2025-02-04 20:20 ` Paul E. McKenney
2025-02-05 14:50 ` Paul E. McKenney
2025-02-05 19:54 ` John Ogness
2025-02-05 20:10 ` Paul E. McKenney
2025-02-05 20:31 ` Paul E. McKenney
2025-02-05 21:22 ` John Ogness
2025-02-05 21:55 ` Paul E. McKenney
2025-02-05 22:20 ` John Ogness [this message]
2025-02-05 22:31 ` John Ogness
2025-02-05 23:50 ` Paul E. McKenney
2025-02-06 8:28 ` John Ogness
2025-02-06 9:58 ` Paul E. McKenney
2025-02-06 9:02 ` Sebastian Andrzej Siewior
2025-02-06 9:59 ` Paul E. McKenney
2025-02-06 10:18 ` Paul E. McKenney
2025-02-06 11:06 ` Petr Mladek
2025-02-06 16:32 ` Paul E. McKenney
2025-01-30 18:53 ` [PATCH rcu v2] 5/5] rcu/nocb: Print segment lengths in show_rcu_nocb_gp_state() Paul E. McKenney
2025-02-06 10:15 ` [PATCH rcu 6/5] Make RCU watch ct_kernel_exit_state() warning Paul E. McKenney
2025-02-06 17:38 ` Boqun Feng
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