From patchwork Thu Sep 14 13:45:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Berg X-Patchwork-Id: 13385456 X-Patchwork-Delegate: johannes@sipsolutions.net 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 61474EEAA41 for ; Thu, 14 Sep 2023 13:45:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239012AbjINNp1 (ORCPT ); Thu, 14 Sep 2023 09:45:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233860AbjINNp0 (ORCPT ); Thu, 14 Sep 2023 09:45:26 -0400 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:242:246e::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2B5081AE for ; Thu, 14 Sep 2023 06:45:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: Message-ID:Date:Subject:Cc:To:From:Content-Type:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-To:Resent-Cc: Resent-Message-ID:In-Reply-To:References; bh=AQTJV92dKyncBnr93TRr208bnS+4tNZaYmxN61fO+LE=; t=1694699122; x=1695908722; b=WPWFksg6A2UlhwbYG0CXjAW3MXH/DMUzm5V/BTmeIvsxZs7Ny+eSabRn/2AFiCDZOOm66czcwf3 b3U4xIYucaRjjC4KXY/znH5HxF5aNDad6ofSiMGzrSUGfwxKrhlj/1BAbstyL8Ws7+gPDWENECWIG d8mHbm1PLJJA6fyNod/ThlpZDisMOv4JbonQvbQpyMMU7VuEdg+yx6CEwCGOgtxFrVj/7XYKx3fYt dIb41GHCA5Nh3cx4Bc+nl3sP28224JRCL2zAyCiDBEERU5Yr9StZGk63TG8obrMnxkU3DjLaklV65 tSuO9S72xvFffgO1KQyuDYVqASvXKG6Y5jNw==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1qgmel-00H5ja-1f; Thu, 14 Sep 2023 15:45:19 +0200 From: Johannes Berg To: linux-wireless@vger.kernel.org Cc: Johannes Berg Subject: [PATCH v3] rfkill: sync before userspace visibility/changes Date: Thu, 14 Sep 2023 15:45:17 +0200 Message-ID: <20230914154516.1037f4633d4c.If977317d8f6a0f557090defcd6aef67628f62ff7@changeid> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org From: Johannes Berg If userspace quickly opens /dev/rfkill after a new instance was created, it might see the old state of the instance from before the sync work runs and may even _change_ the state, only to have the sync work change it again. Fix this by doing the sync inline where needed, not just for /dev/rfkill but also for sysfs. Signed-off-by: Johannes Berg --- v2: add lockdep assert v3: fix compilation ... d'oh --- net/rfkill/core.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/net/rfkill/core.c b/net/rfkill/core.c index 01fca7a10b4b..08630896b6c8 100644 --- a/net/rfkill/core.c +++ b/net/rfkill/core.c @@ -48,6 +48,7 @@ struct rfkill { bool persistent; bool polling_paused; bool suspended; + bool need_sync; const struct rfkill_ops *ops; void *data; @@ -368,6 +369,17 @@ static void rfkill_set_block(struct rfkill *rfkill, bool blocked) rfkill_event(rfkill); } +static void rfkill_sync(struct rfkill *rfkill) +{ + lockdep_assert_held(&rfkill_global_mutex); + + if (!rfkill->need_sync) + return; + + rfkill_set_block(rfkill, rfkill_global_states[rfkill->type].cur); + rfkill->need_sync = false; +} + static void rfkill_update_global_state(enum rfkill_type type, bool blocked) { int i; @@ -730,6 +742,10 @@ static ssize_t soft_show(struct device *dev, struct device_attribute *attr, { struct rfkill *rfkill = to_rfkill(dev); + mutex_lock(&rfkill_global_mutex); + rfkill_sync(rfkill); + mutex_unlock(&rfkill_global_mutex); + return sysfs_emit(buf, "%d\n", (rfkill->state & RFKILL_BLOCK_SW) ? 1 : 0); } @@ -751,6 +767,7 @@ static ssize_t soft_store(struct device *dev, struct device_attribute *attr, return -EINVAL; mutex_lock(&rfkill_global_mutex); + rfkill_sync(rfkill); rfkill_set_block(rfkill, state); mutex_unlock(&rfkill_global_mutex); @@ -783,6 +800,10 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr, { struct rfkill *rfkill = to_rfkill(dev); + mutex_lock(&rfkill_global_mutex); + rfkill_sync(rfkill); + mutex_unlock(&rfkill_global_mutex); + return sysfs_emit(buf, "%d\n", user_state_from_blocked(rfkill->state)); } @@ -805,6 +826,7 @@ static ssize_t state_store(struct device *dev, struct device_attribute *attr, return -EINVAL; mutex_lock(&rfkill_global_mutex); + rfkill_sync(rfkill); rfkill_set_block(rfkill, state == RFKILL_USER_STATE_SOFT_BLOCKED); mutex_unlock(&rfkill_global_mutex); @@ -1032,14 +1054,10 @@ static void rfkill_uevent_work(struct work_struct *work) static void rfkill_sync_work(struct work_struct *work) { - struct rfkill *rfkill; - bool cur; - - rfkill = container_of(work, struct rfkill, sync_work); + struct rfkill *rfkill = container_of(work, struct rfkill, sync_work); mutex_lock(&rfkill_global_mutex); - cur = rfkill_global_states[rfkill->type].cur; - rfkill_set_block(rfkill, cur); + rfkill_sync(rfkill); mutex_unlock(&rfkill_global_mutex); } @@ -1087,6 +1105,7 @@ int __must_check rfkill_register(struct rfkill *rfkill) round_jiffies_relative(POLL_INTERVAL)); if (!rfkill->persistent || rfkill_epo_lock_active) { + rfkill->need_sync = true; schedule_work(&rfkill->sync_work); } else { #ifdef CONFIG_RFKILL_INPUT @@ -1171,6 +1190,7 @@ static int rfkill_fop_open(struct inode *inode, struct file *file) ev = kzalloc(sizeof(*ev), GFP_KERNEL); if (!ev) goto free; + rfkill_sync(rfkill); rfkill_fill_event(&ev->ev, rfkill, RFKILL_OP_ADD); list_add_tail(&ev->list, &data->events); }