From nobody Tue Apr 7 22:19:30 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 4C36BC433FE for ; Wed, 19 Oct 2022 15:06:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231903AbiJSPGZ (ORCPT ); Wed, 19 Oct 2022 11:06:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52546 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230383AbiJSPFj (ORCPT ); Wed, 19 Oct 2022 11:05:39 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9676F1C2EB3 for ; Wed, 19 Oct 2022 07:59:12 -0700 (PDT) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1666191379; 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=dEfLDywQMbLFMveMIU5ztmggdkM8VKhqRGZUba4knEA=; b=tvGWDuIbnMg81nElIpNQcHDQap243WbjOFmLBBssheT3WAcSo/uy+6Y/V1xLaZOuvbqvoP HGWUcc6muabTL3JhrtCL2O+nHHlD1uN8YVPQtxkig8QS8ESpv/V3WRMZA7Rxl4IIndi7hD szwUUd+8jDai9nm38yOHM416UH1skAKg+0nBI9frWXFXAUAQs4OkB5nXnBEBkEVbgTC1Rk qZ92WfVER0K26YNlgAgm71hLsBMCs+JmDbBTQmx0vFv52LhECZBDo3JbTp3eTUIpFu0dzy 5cZYtV6xxBzm2eo129s+wAAZgFZr0dg9IA7FHp+XlWd3FtdHSpugj1GkLYE18g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1666191379; 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=dEfLDywQMbLFMveMIU5ztmggdkM8VKhqRGZUba4knEA=; b=zJjK8oc9MpyW+AN+CgjCFO34fO7H6UGzAb1JPwNkz17MJ2pO3wmfGFId0+ak7aOpZp8Q+5 uWrTfF0L395aPXBg== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: [PATCH printk v2 32/38] printk: __pr_flush: use srcu console list iterator Date: Wed, 19 Oct 2022 17:01:54 +0206 Message-Id: <20221019145600.1282823-33-john.ogness@linutronix.de> In-Reply-To: <20221019145600.1282823-1-john.ogness@linutronix.de> References: <20221019145600.1282823-1-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. 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 809c43e596d8..2faa6e3e2fb8 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3454,6 +3454,7 @@ 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 @@ -3464,9 +3465,15 @@ 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)) @@ -3475,6 +3482,7 @@ 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