From nobody Mon Apr 13 17:07:21 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A930DC433FE for ; Mon, 14 Nov 2022 16:30:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237660AbiKNQab (ORCPT ); Mon, 14 Nov 2022 11:30:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237557AbiKNQ3q (ORCPT ); Mon, 14 Nov 2022 11:29:46 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5476E1CB07 for ; Mon, 14 Nov 2022 08:29:42 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1668443381; 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=gNqL8lThA4YIywGDMJUU+3tDmR/wiL7uckrDiJUm3Yc=; b=4P34KEWdum5Ad8J25GcIpklGjPLZyfP61f2N+FJq/EjuBLOCGQ402uYOuCvoGbXhkJRKlw TAFpdgqASC2/Qdr7QkpAThBldBcPuWfFfy5BtsG45GN3AISccx9ynbRBWAGkTSTgUcFfLP eLu1zs+FP/0ktSIiFPbtmQnqSC3lnyfQ0HrXy03qxk0YTMMqBhSxaXLyv4uc3dWa21Ln7t Wz4JMJAQcWlDqGjr0NBiQWWSiGOX4WyU9l/ySqaJpdS960EPrw/MOxErMLy0Co1qG++59U fTuggTBbCuSKexyxD578FCD/vn9pCaF5Qttt8ZjvuQ5uKVEPwa2YZRxbVtPSbA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1668443381; 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=gNqL8lThA4YIywGDMJUU+3tDmR/wiL7uckrDiJUm3Yc=; b=NtJVSn5Mg5MJsfN6WJJF9AlssUQDo7vZxv3r93RxJ++DnBUK7rFjhIZE4JTLWwLHlvVAzC epjYOkxx+Piio4Bg== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: [PATCH printk v4 15/39] printk: __pr_flush: use srcu console list iterator Date: Mon, 14 Nov 2022 17:35:08 +0106 Message-Id: <20221114162932.141883-16-john.ogness@linutronix.de> In-Reply-To: <20221114162932.141883-1-john.ogness@linutronix.de> References: <20221114162932.141883-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Use srcu console list iteration for console list traversal. Document why the console_lock is still necessary. Note that this is a preparatory change for when console_lock no longer provides synchronization for the console list. Signed-off-by: John Ogness Reviewed-by: Petr Mladek --- kernel/printk/printk.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index b37ca16abbd0..3d9e5bb1a50b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3532,6 +3532,7 @@ static bool __pr_flush(struct console *con, int timeo= ut_ms, bool reset_on_progre struct console *c; u64 last_diff =3D 0; u64 printk_seq; + int cookie; u64 diff; u64 seq; =20 @@ -3542,9 +3543,15 @@ static bool __pr_flush(struct console *con, int time= out_ms, bool reset_on_progre for (;;) { diff =3D 0; =20 + /* + * Hold the console_lock to guarantee safe access to + * console->seq and to prevent changes to @console_suspended + * until all consoles have been processed. + */ console_lock(); =20 - for_each_console(c) { + cookie =3D console_srcu_read_lock(); + for_each_console_srcu(c) { if (con && con !=3D c) continue; if (!console_is_usable(c)) @@ -3553,6 +3560,7 @@ static bool __pr_flush(struct console *con, int timeo= ut_ms, bool reset_on_progre if (printk_seq < seq) diff +=3D seq - printk_seq; } + console_srcu_read_unlock(cookie); =20 /* * If consoles are suspended, it cannot be expected that they --=20 2.30.2