From patchwork Tue Feb 25 18:33:28 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13990533 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 02FC6198E63; Tue, 25 Feb 2025 18:33:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740508410; cv=none; b=bzmx3T8G3gFZCZaE/pF9y3/OisO/3nx0PdhFx/dsHGFUWTw44T3FnpV3HmMLv483rqKbYm5XBoJpQSkycW6jc8JDLPFamFvZ6eAAjfWFBT7JMekkiMXjv+53cTXBWjSq1nKFQbLiEmj/iDNgIUHZkGQ5eqzCiCmpxLN0Vt9/CL8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740508410; c=relaxed/simple; bh=bBItIqzwltwC+TCsuqofxmj3GfVFhtE23r50c2BKncQ=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=l6nTvDw5y1rxAoDTIoUMQYZPIXF/Jc7uIxZrfDi1U74rLOoXDscgXEeFFe/QiiL7tviGtH6D6+srS7j8zArboPDZbZTKNPfoepKyoQK/b+MRURXvtuPpHKootVW1eF02//nogqCcJ88djAcpKkEW/7H22hqPKaBxvla5kpykhP0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=byILlQzb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="byILlQzb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61763C4CEE2; Tue, 25 Feb 2025 18:33:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740508409; bh=bBItIqzwltwC+TCsuqofxmj3GfVFhtE23r50c2BKncQ=; h=Date:From:To:Cc:Subject:Reply-To:From; b=byILlQzbc5JGnFIQUA0x5qdJlCR0vxEvzYMNH6CrS1ES+sOY0ipN8SnyTX7AeXkJw O7aHFFrdrUiaQvQFOZKa0+ECESde8BT0DKOQaU978clpnH0k5gdkSVkqzCjQV1n6zE Qb6p985UtN50Pq53joGLRy8KSSrsXqGsv5r+JooCRkNsK6miRm+GmB44zvNL0Vjgqb ozcStsf9w2bROIvxar3WjDgFk/aMpOYFi8DKRUg7DsGer0bVGOn9+/M7kupUn2OznI o2H+aRsgqUCLTJKIeN0Z4V6RnrZhRJMbb1lkfU02Cl2d6NaSXtKXMw0mxCDfHgQCmx 7nZgOr98SGN2Q== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 0514ECE045A; Tue, 25 Feb 2025 10:33:29 -0800 (PST) Date: Tue, 25 Feb 2025 10:33:28 -0800 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, kernel-team@meta.com, rcu@vger.kernel.org Cc: john.ogness@linutronix.de, pmladek@suse.com, rostedt@goodmis.org, senozhatsky@chromium.org, boqun.feng@gmail.com Subject: [PATCH printk] Flush console log from kernel_power_off() Message-ID: <5f743488-dc2a-4f19-bdda-cf50b9314832@paulmck-laptop> Reply-To: paulmck@kernel.org Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Kernels built with CONFIG_PREEMPT_RT=y can lose significant console output and shutdown time, which hides shutdown-time RCU issues from rcutorture. Therefore, make pr_flush() public and invoke it after then last print in kernel_power_off(). [ paulmck: Apply John Ogness feedback. ] [ paulmck: Appy Sebastian Andrzej Siewior feedback. ] [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Paul E. McKenney Reviewed-by: John Ogness Reviewed-by: Petr Mladek Cc: Steven Rostedt Cc: Sergey Senozhatsky --- include/linux/printk.h | 6 ++++++ kernel/printk/printk.c | 4 +--- kernel/reboot.c | 1 + 3 files changed, 8 insertions(+), 3 deletions(-) diff --git a/include/linux/printk.h b/include/linux/printk.h index 4217a9f412b26..5b462029d03c1 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -207,6 +207,7 @@ void printk_legacy_allow_panic_sync(void); extern bool nbcon_device_try_acquire(struct console *con); extern void nbcon_device_release(struct console *con); void nbcon_atomic_flush_unsafe(void); +bool pr_flush(int timeout_ms, bool reset_on_progress); #else static inline __printf(1, 0) int vprintk(const char *s, va_list args) @@ -315,6 +316,11 @@ static inline void nbcon_atomic_flush_unsafe(void) { } +static inline bool pr_flush(int timeout_ms, bool reset_on_progress) +{ + return true; +} + #endif bool this_cpu_in_panic(void); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 07668433644b8..057db78876cd9 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2461,7 +2461,6 @@ asmlinkage __visible int _printk(const char *fmt, ...) } EXPORT_SYMBOL(_printk); -static bool pr_flush(int timeout_ms, bool reset_on_progress); static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress); #else /* CONFIG_PRINTK */ @@ -2474,7 +2473,6 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre static u64 syslog_seq; -static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; } static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; } #endif /* CONFIG_PRINTK */ @@ -4466,7 +4464,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre * Context: Process context. May sleep while acquiring console lock. * Return: true if all usable printers are caught up. */ -static bool pr_flush(int timeout_ms, bool reset_on_progress) +bool pr_flush(int timeout_ms, bool reset_on_progress) { return __pr_flush(NULL, timeout_ms, reset_on_progress); } diff --git a/kernel/reboot.c b/kernel/reboot.c index b5a8569e5d81f..41ab9e1ba3575 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -704,6 +704,7 @@ void kernel_power_off(void) migrate_to_reboot_cpu(); syscore_shutdown(); pr_emerg("Power down\n"); + pr_flush(1000, true); kmsg_dump(KMSG_DUMP_SHUTDOWN); machine_power_off(); }