From nobody Mon Feb 9 17:23:50 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 0FFC6329383; Thu, 13 Nov 2025 16:03:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763049835; cv=none; b=DtsiOyd9HFqT2iMniS0MOYaL8N4xkfYipCTi+KVmKIAoR6BhkTgz/4Sbelu0B0xEkaW4zZmZtQYjV7nf9+lvox/X5JHgsWqfM/IQR1HdkoNHp+Li2G8IPoxk2TT+H0dcB2SQl3EzGS41Ywn3elui2a3M1MXhmEENxkv2PZURCNQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763049835; c=relaxed/simple; bh=+EQqqr4aXZKCkc39s9Hy2xPKj/wIDgdN7Ty015/QYV8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wsv+G1DwScjgV54weIC8aSDVTl5M63aCfLYwXvymOolvoa5vaDoUrWgEOV8Qs9WUqXUS9QjXrkfNlzcWFhmXUyojxMsoQ7AE4JCRjcmH5aQPUMZQi0L9BL+tMhsX8BosG3454J0JlV1I4IXSsLqCZ8VL6Ck6BMyno5zq4YOQda0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=toprBaN9; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=QKpow0Bd; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="toprBaN9"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="QKpow0Bd" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1763049832; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5YmTV8R+fRrPYd6LEUl1jTZ6XIQQXOMozxx7WQ79gQI=; b=toprBaN99tTfB/Tq+SjOjm06E1o8m461wpDp2dfHOrVhzfq6YlOsTwMr0FcaAHhjXwiMOP C5HUjiJI/qEQaunvHYpPOgFczHiXPdaqW7RqVeNA9quNe0j5CdP732I7N6so9CkwLlLEjH 0/QmQrT6TFc4u6X4m7D46KWC5DH+dyFcGmear2YvZvWXDOBJ32ALDRNewu0dvqwaJ/wHf6 O6rWwfYXZtVZPD8SkxoJVvtpkj+1wtJYKLdzL8YeGtbKkKmnh7h6G3V/qMJnZK3EIM9UIC OPHSqfnzZ3P7zhIzQs2jmSJu2nNwqQ+cGY5jYRKVOwSPqcv7tYNboCOzxWCawg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1763049832; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5YmTV8R+fRrPYd6LEUl1jTZ6XIQQXOMozxx7WQ79gQI=; b=QKpow0Bd2zNzpUTWKObMcGpzxkEwq3cAchoZTiSKkaQSlWrJOA54ZceMq/l55F7f1kt94Q HfXRuvQx6O4I95Cw== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Sherry Sun , Jacky Bai , Jon Hunter , Thierry Reding , Derek Barbosa , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH printk v2 1/2] printk: Allow printk_trigger_flush() to flush all types Date: Thu, 13 Nov 2025 17:09:47 +0106 Message-ID: <20251113160351.113031-2-john.ogness@linutronix.de> In-Reply-To: <20251113160351.113031-1-john.ogness@linutronix.de> References: <20251113160351.113031-1-john.ogness@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently printk_trigger_flush() only triggers legacy offloaded flushing, even if that may not be the appropriate method to flush for currently registered consoles. (The function predates the NBCON consoles.) Since commit 6690d6b52726 ("printk: Add helper for flush type logic") there is printk_get_console_flush_type(), which also considers NBCON consoles and reports all the methods of flushing appropriate based on the system state and consoles available. Update printk_trigger_flush() to use printk_get_console_flush_type() to appropriately flush registered consoles. Suggested-by: Petr Mladek Signed-off-by: John Ogness Reviewed-by: Petr Mladek --- kernel/printk/nbcon.c | 2 +- kernel/printk/printk.c | 23 ++++++++++++++++++++++- 2 files changed, 23 insertions(+), 2 deletions(-) diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c index 558ef31779760..73f315fd97a3e 100644 --- a/kernel/printk/nbcon.c +++ b/kernel/printk/nbcon.c @@ -1849,7 +1849,7 @@ void nbcon_device_release(struct console *con) if (console_trylock()) console_unlock(); } else if (ft.legacy_offload) { - printk_trigger_flush(); + defer_console_output(); } } console_srcu_read_unlock(cookie); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 5aee9ffb16b9a..dc89239cf1b58 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -4567,9 +4567,30 @@ void defer_console_output(void) __wake_up_klogd(PRINTK_PENDING_WAKEUP | PRINTK_PENDING_OUTPUT); } =20 +/** + * printk_trigger_flush - Attempt to flush printk buffer to consoles. + * + * If possible, flush the printk buffer to all consoles in the caller's + * context. If offloading is available, trigger deferred printing. + * + * This is best effort. Depending on the system state, console states, + * and caller context, no actual flushing may result from this call. + */ void printk_trigger_flush(void) { - defer_console_output(); + struct console_flush_type ft; + + printk_get_console_flush_type(&ft); + if (ft.nbcon_atomic) + nbcon_atomic_flush_pending(); + if (ft.nbcon_offload) + nbcon_kthreads_wake(); + if (ft.legacy_direct) { + if (console_trylock()) + console_unlock(); + } + if (ft.legacy_offload) + defer_console_output(); } =20 int vprintk_deferred(const char *fmt, va_list args) --=20 2.47.3