From patchwork Thu Sep 17 07:44:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muchun Song X-Patchwork-Id: 1365922 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.a=rsa-sha256 header.s=20150623 header.b=idh71yNv; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BsTXx2vvcz9sS8 for ; Thu, 17 Sep 2020 17:45:53 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726322AbgIQHpq (ORCPT ); Thu, 17 Sep 2020 03:45:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726306AbgIQHpH (ORCPT ); Thu, 17 Sep 2020 03:45:07 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC91EC06174A for ; Thu, 17 Sep 2020 00:45:06 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id gf14so798010pjb.5 for ; Thu, 17 Sep 2020 00:45:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=2N3mWH4dWBjYIgMqML5SFtLQn8Wc+WVJixIOAPyOzJA=; b=idh71yNvBVxWLoWXnqR9b8hBq73P+5oYksH6cYCmUxaJLP3zItcAtvxAsAEejSKGD6 OOnwMp8FC7fdVZGvrLSajJRiOAdWaiH7Ab3/T8FSAi3AYtwsXOtMe1KxQCTIq2ZfIfOE Bu6qWr+/agn6NHYaPkONMNJXpevY4g5TXNbSapVm1mCRUaBqrcdOoeAe63iXk47IHqRo esN9NiE0x3+j9s4y4bD3NKKQnQofCIUBsNHFaMc0rXJAsC3KUusnfWyD8cadGXUKOuyM ndR0r5mTn+vArVbFj/8G+gS8Lo/xY9SiWnUEgcjoxZzvz76QzjKbgVGVEbm+5jSk/X/h 9nbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=2N3mWH4dWBjYIgMqML5SFtLQn8Wc+WVJixIOAPyOzJA=; b=b/UBn8HB5vwoRpelF2n/347lc4IOLbjaxuCY7yNw8+F/LhV62TieKy6hGKTdU9N7Jf xx44hEbUvq0/Ik17/AMdB/obc1k9pJigaSvkoZDBhrs3QOh9lpC9+MTX3C5uitdWmu/M zwNki4qTj185agKaU2WMWT1HN4DYnxhDlEU6UNPUZ6ia4h6NgH/rkndKJhoyA+STInjt iSaVeNX5a60vcXBsaW2OqEd7084auWJrN4qTd2B4TfMzl9BdMFWDD7v1RVIw7XZ62K+U MDPqzyYSqU/2FUt+Mz2pEaQi3Ub2jJoCwlLnH9+8kQmeF+NFeQTpMbmpNaiirMga2UcS VNIg== X-Gm-Message-State: AOAM530gBqU98+3xV0cOwHfT1i8UESTclbANAaM/9EZQQ1+eE/zu91Xh 10Y5TWPHrpvOHWcNFkpUlhbygQ== X-Google-Smtp-Source: ABdhPJwXaMllPXLLBBq/ZdkN+0JpO5r0KMFYX2Af8lAj/0slXE5K3cOn/uUBCY85+zsg2ZmTQcGeuA== X-Received: by 2002:a17:90b:20d1:: with SMTP id ju17mr6874545pjb.134.1600328706465; Thu, 17 Sep 2020 00:45:06 -0700 (PDT) Received: from bogon.bytedance.net ([103.136.220.66]) by smtp.gmail.com with ESMTPSA id v26sm17786351pgo.83.2020.09.17.00.45.01 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Sep 2020 00:45:05 -0700 (PDT) From: Muchun Song To: ast@kernel.org, daniel@iogearbox.net, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, andriin@fb.com, john.fastabend@gmail.com, kpsingh@chromium.org Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Muchun Song Subject: [RFC PATCH] bpf: Fix potential call bpf_link_free() in atomic context Date: Thu, 17 Sep 2020 15:44:53 +0800 Message-Id: <20200917074453.20621-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The in_atomic macro cannot always detect atomic context. In particular, it cannot know about held spinlocks in non-preemptible kernels. Although, there is no user call bpf_link_put() with holding spinlock now. Be the safe side, we can avoid this in the feature. Signed-off-by: Muchun Song Acked-by: Song Liu Acked-by: Andrii Nakryiko --- kernel/bpf/syscall.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 178c147350f5..6347be0a5c82 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2345,12 +2345,8 @@ void bpf_link_put(struct bpf_link *link) if (!atomic64_dec_and_test(&link->refcnt)) return; - if (in_atomic()) { - INIT_WORK(&link->work, bpf_link_put_deferred); - schedule_work(&link->work); - } else { - bpf_link_free(link); - } + INIT_WORK(&link->work, bpf_link_put_deferred); + schedule_work(&link->work); } static int bpf_link_release(struct inode *inode, struct file *filp)