From nobody Wed Sep 10 02:48:45 2025 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 46DA4C0015E for ; Fri, 28 Jul 2023 00:03:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231723AbjG1ADB (ORCPT ); Thu, 27 Jul 2023 20:03:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231481AbjG1ACn (ORCPT ); Thu, 27 Jul 2023 20:02:43 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 025E0170D for ; Thu, 27 Jul 2023 17:02:42 -0700 (PDT) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1690502559; 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=xb4IARB7ZGs0NFGdahNKOcVuwqCsWQdgRW9ky2NkqP0=; b=bHC60CvVn0k5V/Ob2wGVruqaoijuC5OhwuGq8OdO28M1v7kmYBNC5Pcqlj112Tv329px04 xoOv0JbDAZi0d03qVzIOkCpF4WQqlZHC5grMzu3eSIEdETyqjHzI4FFpNF4tAECymfMoU/ 1prM90FTfK0afeyH9Y3/MWGPlJWUQ8RpEzLBEje2JR+Dgnci+X/hzJ6zRCI7/1JSuJ7MnM gQS9e8ch2R/Fu0sDtea01twbCChPWz4ci6k472ezTOlD3l01I+CjNir1j30oIDTNLEtWJe N8uEgfZ9p79D7fCuV51NoJidOWaApXHLw0GmUz/EpfFxkjiqifa9L1ptEHhEbA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1690502559; 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=xb4IARB7ZGs0NFGdahNKOcVuwqCsWQdgRW9ky2NkqP0=; b=OClN8Ozq+PUpq9KrNWc9iSN08LxWbFx7BcujZAphNTRhSaICw0IwD2aaHDjeSPsnVeuht6 4AgtmvM4HAAqv/CA== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman Subject: [PATCH printk v2 8/8] printk: nbcon: Add functions for drivers to mark unsafe regions Date: Fri, 28 Jul 2023 02:08:33 +0206 Message-Id: <20230728000233.50887-9-john.ogness@linutronix.de> In-Reply-To: <20230728000233.50887-1-john.ogness@linutronix.de> References: <20230728000233.50887-1-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" From: Thomas Gleixner For the write_atomic callback, the console driver may have unsafe regions that need to be appropriately marked. Provide functions that accept the nbcon_write_context struct to allow for the driver to enter and exit unsafe regions. Co-developed-by: John Ogness Signed-off-by: John Ogness Signed-off-by: Thomas Gleixner (Intel) --- include/linux/console.h | 4 ++++ kernel/printk/printk_nbcon.c | 41 +++++++++++++++++++++++++++++++++++- 2 files changed, 44 insertions(+), 1 deletion(-) diff --git a/include/linux/console.h b/include/linux/console.h index 3d129b2b70a1..e4ce1015627c 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -456,8 +456,12 @@ static inline bool console_is_registered(const struct = console *con) =20 #ifdef CONFIG_PRINTK extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt); +extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt); +extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt); #else static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { = return false; } +static inline bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) {= return false; } +static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { = return false; } #endif =20 extern int console_set_on_cmdline; diff --git a/kernel/printk/printk_nbcon.c b/kernel/printk/printk_nbcon.c index e1f0e4278ffa..57b7539bbbb2 100644 --- a/kernel/printk/printk_nbcon.c +++ b/kernel/printk/printk_nbcon.c @@ -761,7 +761,6 @@ EXPORT_SYMBOL_GPL(nbcon_can_proceed); * * Internal helper to avoid duplicated code */ -__maybe_unused static bool nbcon_context_update_unsafe(struct nbcon_context *ctxt, bool u= nsafe) { struct console *con =3D ctxt->console; @@ -787,6 +786,46 @@ static bool nbcon_context_update_unsafe(struct nbcon_c= ontext *ctxt, bool unsafe) return true; } =20 +/** + * nbcon_enter_unsafe - Enter an unsafe region in the driver + * @wctxt: The write context that was handed to the write function + * + * Return: True if the state is correct. False if ownership was + * handed over or taken. + * + * When this function returns false then the calling context is no longer + * the owner and is no longer allowed to go forward. In this case it must + * back out immediately and carefully. The buffer content is also no longer + * trusted since it no longer belongs to the calling context. + */ +bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) +{ + struct nbcon_context *ctxt =3D &ACCESS_PRIVATE(wctxt, ctxt); + + return nbcon_context_update_unsafe(ctxt, true); +} +EXPORT_SYMBOL_GPL(nbcon_enter_unsafe); + +/** + * nbcon_exit_unsafe - Exit an unsafe region in the driver + * @wctxt: The write context that was handed to the write function + * + * Return: True if the state is correct. False if ownership was + * handed over or taken. + * + * When this function returns false then the calling context is no longer + * the owner and is no longer allowed to go forward. In this case it must + * back out immediately and carefully. The buffer content is also no longer + * trusted since it no longer belongs to the calling context. + */ +bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) +{ + struct nbcon_context *ctxt =3D &ACCESS_PRIVATE(wctxt, ctxt); + + return nbcon_context_update_unsafe(ctxt, false); +} +EXPORT_SYMBOL_GPL(nbcon_exit_unsafe); + /** * nbcon_emit_next_record - Emit a record in the acquired context * @wctxt: The write context that will be handed to the write function --=20 2.39.2