From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE, SPF_NONE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 3419B1F46C for ; Thu, 16 Jan 2020 02:40:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729697AbgAPCkg (ORCPT ); Wed, 15 Jan 2020 21:40:36 -0500 Received: from mail-qk1-f194.google.com ([209.85.222.194]:44969 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729662AbgAPCkg (ORCPT ); Wed, 15 Jan 2020 21:40:36 -0500 Received: by mail-qk1-f194.google.com with SMTP id w127so17775110qkb.11 for ; Wed, 15 Jan 2020 18:40:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=usp-br.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=+fWAmaFn5K7Cpfz95nO1TxACvul7649Ek3I9CA229Oc=; b=f45/uLgvV/PM47BycHqk2kwMNnP8gofeW+AcJ6JWyfMjZLVthnIkixPYpgp26td/PQ PvlfPHvCWnhvxWtKvblzX8Ytobbp2+y3ZNdG4P3nmaZrL1CZFHCeNv/YTmJwcBQlD46v IbvB9TWdG02d9eC/UKcQZy8iSRW/3qpOyd18M7eiwtwhxxLzFoEcZASl8A1AsRtmzEyC 7IcIIc2qOMXDLwvwim+1HmxSQC/N+YQ5NS8A1iw9JzdBg82RZ1SVncoHddVEb2Ol4YkF 4DDzlquWTNdE3ysFpcAdcFzzVV0KXa4Jxyefxwjh/CxpkPON+z/bxoOJpmAvx3ahyTmT U/Ig== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=+fWAmaFn5K7Cpfz95nO1TxACvul7649Ek3I9CA229Oc=; b=G7aFQkUgvVfZOIWXwukRU0sp+Im1M0fDUeuqui9yyWAixlRqV1k/zFcBShxUr9FvPD Cw8u9vner2cIiPjypjBl1ZBHBv9mWk8jzjApQT3+rum7lGf+QMVetaZNVJLB/AAt3qfw YePg8vKFuyJWGcHBe2luwbiYfXYKEQm2avDnXPynjwdPQge9KFhqA3IprZcVSb5iya30 UxsV1BqslpJ87WosAgc/s+0HY645t+r56xjEdGjbWw2t6OSyjHjE2K0QFQzDLShJ4nH1 i3VNTrSfGAieMMvxhtFmxqEgnRU7kwNa5z5V5KYc0x0S3DAccDrB72F3TXVTvhRBbCyL 5z9w== X-Gm-Message-State: APjAAAUGyORzBYcteEfALZW4sXDUhzwXKxpWzAwsxZFCUSJGpDcnS1Za uNLryG6YJIdezcRmNcrgnShdY+cBrLo= X-Google-Smtp-Source: APXvYqyGpvC/6zekmRW549IuRlkmcUEV60RdBUPC4eIiVWwRsD7JsGbjPjhqbSDNayMvJIt7VkkH1A== X-Received: by 2002:a37:9a46:: with SMTP id c67mr26141627qke.308.1579142434963; Wed, 15 Jan 2020 18:40:34 -0800 (PST) Received: from mango.spo.virtua.com.br ([2804:14c:81:942d::1]) by smtp.gmail.com with ESMTPSA id u24sm9381289qkm.40.2020.01.15.18.40.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jan 2020 18:40:34 -0800 (PST) From: Matheus Tavares To: git@vger.kernel.org Cc: christian.couder@gmail.com, gitster@pobox.com, jrnieder@gmail.com, olyatelezhnaya@gmail.com, pclouds@gmail.com, jonathantanmy@google.com, peff@peff.net, Ramkumar Ramachandra , Eric Wong Subject: [PATCH v3 01/12] grep: fix race conditions on userdiff calls Date: Wed, 15 Jan 2020 23:39:49 -0300 Message-Id: X-Mailer: git-send-email 2.24.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org git-grep uses an internal grep_read_mutex to protect object reading operations. Similarly, there's a grep_attr_mutex to protect calls to the gitattributes machinery. However, two of the three functions protected by the last mutex may also perform object reading, as seen below: - userdiff_get_textconv() > notes_cache_init() > notes_cache_match_validity() > lookup_commit_reference_gently() > parse_object() > repo_has_object_file() > repo_has_object_file_with_flags() > oid_object_info_extended() - userdiff_find_by_path() > git_check_attr() > collect_some_attrs() > prepare_attr_stack() > read_attr() > read_attr_from_index() > read_blob_data_from_index() > read_object_file() As these calls are not protected by grep_read_mutex, there might be race conditions with other threads performing object reading (e.g. threads calling fill_textconv() at grep.c:fill_textconv_grep()). To prevent that, let's make sure to acquire the lock before both of these calls. Note: this patch might slow down the threaded grep in worktree, for the sake of thread-safeness. However, in the following patches, we should regain performance by replacing grep_read_mutex for an internal object reading lock and allowing parallel inflation during object reading. Signed-off-by: Matheus Tavares --- grep.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/grep.c b/grep.c index 0552b127c1..c028f70aba 100644 --- a/grep.c +++ b/grep.c @@ -1816,7 +1816,9 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle * is not thread-safe. */ grep_attr_lock(); + grep_read_lock(); textconv = userdiff_get_textconv(opt->repo, gs->driver); + grep_read_unlock(); grep_attr_unlock(); } @@ -2184,8 +2186,11 @@ void grep_source_load_driver(struct grep_source *gs, return; grep_attr_lock(); - if (gs->path) + if (gs->path) { + grep_read_lock(); gs->driver = userdiff_find_by_path(istate, gs->path); + grep_read_unlock(); + } if (!gs->driver) gs->driver = userdiff_find_by_name("default"); grep_attr_unlock(); -- 2.24.1