From mboxrd@z Thu Jan 1 00:00:00 1970 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 87F37C433FE for ; Wed, 19 Oct 2022 08:51:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231676AbiJSIvV (ORCPT ); Wed, 19 Oct 2022 04:51:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231686AbiJSItE (ORCPT ); Wed, 19 Oct 2022 04:49:04 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 656AF91853; Wed, 19 Oct 2022 01:47:00 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B4924B822FF; Wed, 19 Oct 2022 08:43:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A257C433D6; Wed, 19 Oct 2022 08:43:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666169011; bh=5WqAnoSjVTSoddkab9lp14xiGFfx7MVSszDGRO/v0Ss=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=v2GuYzraoAIVX/utpa6O3f7nQBhJ+dpSlQD/i/KtLiKs74ty02VQSCfulgN3JeJ02 xV3JVhPIF4sMubqy/h8xM7AHwOEcgWXQfRT9fjhgpt4PeJSJGSE3kAYRwgKwILU/Hl HS9hKIeok7tQeiMgs96E2tiW+ntqzAC0kybTP/bE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gregory Erwin , "Jason A. Donenfeld" , Herbert Xu , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Kalle Valo Subject: [PATCH 6.0 111/862] hwrng: core - let sleep be interrupted when unregistering hwrng Date: Wed, 19 Oct 2022 10:23:18 +0200 Message-Id: <20221019083254.837224927@linuxfoundation.org> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221019083249.951566199@linuxfoundation.org> References: <20221019083249.951566199@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jason A. Donenfeld commit 36cb6494429bd64b27b7ff8b4af56f8e526da2b4 upstream. There are two deadlock scenarios that need addressing, which cause problems when the computer goes to sleep, the interface is set down, and hwrng_unregister() is called. When the deadlock is hit, sleep is delayed for tens of seconds, causing it to fail. These scenarios are: 1) The hwrng kthread can't be stopped while it's sleeping, because it uses msleep_interruptible() which does not react to kthread_stop. 2) A normal user thread can't be interrupted by hwrng_unregister() while it's sleeping, because hwrng_unregister() is called from elsewhere. We solve both issues by add a completion object called dying that fulfils waiters once we have started the process in hwrng_unregister. At the same time, we should cleanup a common and useless dmesg splat in the same area. Cc: Reported-by: Gregory Erwin Fixes: fcd09c90c3c5 ("ath9k: use hw_random API instead of directly dumping into random.c") Link: https://lore.kernel.org/all/CAO+Okf6ZJC5-nTE_EJUGQtd8JiCkiEHytGgDsFGTEjs0c00giw@mail.gmail.com/ Link: https://lore.kernel.org/lkml/CAO+Okf5k+C+SE6pMVfPf-d8MfVPVq4PO7EY8Hys_DVXtent3HA@mail.gmail.com/ Link: https://bugs.archlinux.org/task/75138 Signed-off-by: Jason A. Donenfeld Signed-off-by: Herbert Xu Acked-by: Toke Høiland-Jørgensen Acked-by: Kalle Valo Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- drivers/char/hw_random/core.c | 19 +++++++++++++++---- drivers/net/wireless/ath/ath9k/rng.c | 3 ++- include/linux/hw_random.h | 3 +++ 3 files changed, 20 insertions(+), 5 deletions(-) --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -507,16 +507,17 @@ static int hwrng_fillfn(void *unused) rng->quality = current_quality; /* obsolete */ quality = rng->quality; mutex_unlock(&reading_mutex); + + if (rc <= 0) + hwrng_msleep(rng, 10000); + put_rng(rng); if (!quality) break; - if (rc <= 0) { - pr_warn("hwrng: no data available\n"); - msleep_interruptible(10000); + if (rc <= 0) continue; - } /* If we cannot credit at least one bit of entropy, * keep track of the remainder for the next iteration @@ -570,6 +571,7 @@ int hwrng_register(struct hwrng *rng) init_completion(&rng->cleanup_done); complete(&rng->cleanup_done); + init_completion(&rng->dying); if (!current_rng || (!cur_rng_set_by_user && rng->quality > current_rng->quality)) { @@ -617,6 +619,7 @@ void hwrng_unregister(struct hwrng *rng) old_rng = current_rng; list_del(&rng->list); + complete_all(&rng->dying); if (current_rng == rng) { err = enable_best_rng(); if (err) { @@ -685,6 +688,14 @@ void devm_hwrng_unregister(struct device } EXPORT_SYMBOL_GPL(devm_hwrng_unregister); +long hwrng_msleep(struct hwrng *rng, unsigned int msecs) +{ + unsigned long timeout = msecs_to_jiffies(msecs) + 1; + + return wait_for_completion_interruptible_timeout(&rng->dying, timeout); +} +EXPORT_SYMBOL_GPL(hwrng_msleep); + static int __init hwrng_modinit(void) { int ret; --- a/drivers/net/wireless/ath/ath9k/rng.c +++ b/drivers/net/wireless/ath/ath9k/rng.c @@ -83,7 +83,8 @@ static int ath9k_rng_read(struct hwrng * if (!wait || !max || likely(bytes_read) || fail_stats > 110) break; - msleep_interruptible(ath9k_rng_delay_get(++fail_stats)); + if (hwrng_msleep(rng, ath9k_rng_delay_get(++fail_stats))) + break; } if (wait && !bytes_read && max) --- a/include/linux/hw_random.h +++ b/include/linux/hw_random.h @@ -50,6 +50,7 @@ struct hwrng { struct list_head list; struct kref ref; struct completion cleanup_done; + struct completion dying; }; struct device; @@ -61,4 +62,6 @@ extern int devm_hwrng_register(struct de extern void hwrng_unregister(struct hwrng *rng); extern void devm_hwrng_unregister(struct device *dve, struct hwrng *rng); +extern long hwrng_msleep(struct hwrng *rng, unsigned int msecs); + #endif /* LINUX_HWRANDOM_H_ */