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 72115CCA482 for ; Thu, 23 Jun 2022 17:54:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235316AbiFWRyC (ORCPT ); Thu, 23 Jun 2022 13:54:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235191AbiFWRv5 (ORCPT ); Thu, 23 Jun 2022 13:51:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 674FEA18D; Thu, 23 Jun 2022 10:12:37 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 9861F61D1E; Thu, 23 Jun 2022 17:12:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 854BBC3411B; Thu, 23 Jun 2022 17:12:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656004355; bh=4+zUTGtNcS5lJ5osrctbx8IJCZEIwR0zeawXRMFO8s0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zF5bsGnIcfK9wG4M+PISXfICsOgAsxRoP4ewgduS+MjxeV5EV6QHnTrQvDJ9Ax7FV fPBUM5+ab//FQ4JeSaCXHDhTOcRMQ+jYI0dqWCpsvmrVqd2BjEhM1Ipdtndimorvz1 sNPbKtVDfHa9B2l4pavM1/T7XaHfO028cAZQrpuM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sebastian Andrzej Siewior , Keerthy , Stephen Boyd , Herbert Xu , "Jason A. Donenfeld" Subject: [PATCH 4.19 012/234] random: Use wait_event_freezable() in add_hwgenerator_randomness() Date: Thu, 23 Jun 2022 18:41:19 +0200 Message-Id: <20220623164343.406758077@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220623164343.042598055@linuxfoundation.org> References: <20220623164343.042598055@linuxfoundation.org> User-Agent: quilt/0.66 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: Stephen Boyd commit 59b569480dc8bb9dce57cdff133853a842dfd805 upstream. Sebastian reports that after commit ff296293b353 ("random: Support freezable kthreads in add_hwgenerator_randomness()") we can call might_sleep() when the task state is TASK_INTERRUPTIBLE (state=1). This leads to the following warning. do not call blocking ops when !TASK_RUNNING; state=1 set at [<00000000349d1489>] prepare_to_wait_event+0x5a/0x180 WARNING: CPU: 0 PID: 828 at kernel/sched/core.c:6741 __might_sleep+0x6f/0x80 Modules linked in: CPU: 0 PID: 828 Comm: hwrng Not tainted 5.3.0-rc7-next-20190903+ #46 RIP: 0010:__might_sleep+0x6f/0x80 Call Trace: kthread_freezable_should_stop+0x1b/0x60 add_hwgenerator_randomness+0xdd/0x130 hwrng_fillfn+0xbf/0x120 kthread+0x10c/0x140 ret_from_fork+0x27/0x50 We shouldn't call kthread_freezable_should_stop() from deep within the wait_event code because the task state is still set as TASK_INTERRUPTIBLE instead of TASK_RUNNING and kthread_freezable_should_stop() will try to call into the freezer with the task in the wrong state. Use wait_event_freezable() instead so that it calls schedule() in the right place and tries to enter the freezer when the task state is TASK_RUNNING instead. Reported-by: Sebastian Andrzej Siewior Tested-by: Sebastian Andrzej Siewior Cc: Keerthy Fixes: ff296293b353 ("random: Support freezable kthreads in add_hwgenerator_randomness()") Signed-off-by: Stephen Boyd Signed-off-by: Herbert Xu Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -327,6 +327,7 @@ #include #include #include +#include #include #include #include @@ -2483,7 +2484,6 @@ void add_hwgenerator_randomness(const ch size_t entropy) { struct entropy_store *poolp = &input_pool; - bool frozen = false; if (unlikely(crng_init == 0)) { crng_fast_load(buffer, count); @@ -2494,13 +2494,11 @@ void add_hwgenerator_randomness(const ch * We'll be woken up again once below random_write_wakeup_thresh, * or when the calling thread is about to terminate. */ - wait_event_interruptible(random_write_wait, - kthread_freezable_should_stop(&frozen) || + wait_event_freezable(random_write_wait, + kthread_should_stop() || ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); - if (!frozen) { - mix_pool_bytes(poolp, buffer, count); - credit_entropy_bits(poolp, entropy); - } + mix_pool_bytes(poolp, buffer, count); + credit_entropy_bits(poolp, entropy); } EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);