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 X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CD55C433E6 for ; Mon, 31 Aug 2020 18:19:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 530552071B for ; Mon, 31 Aug 2020 18:19:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897999; bh=/HE/fGcqYX59CrpNFV584u9l8p/t5BIN7wRnHk0mx8Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=RA0GQcerEq2C8z7XDKgjVJzeu6/KTJuRE99RSmM2LUthbqNzi2nxfprWYQeGL/c6+ 4XMxwtfpDCNvt5nmIiPRvDF1q+FKjsZ5aA0leHOdyceFdPH+XTd3ZoXxWDVwN4n+ip NrnH0Zg7gQTqtQYhdpMBUSthof5rdA/UXLzZqCmE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729779AbgHaST6 (ORCPT ); Mon, 31 Aug 2020 14:19:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:51680 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729500AbgHaSSI (ORCPT ); Mon, 31 Aug 2020 14:18:08 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4A73A20EDD; Mon, 31 Aug 2020 18:18:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897888; bh=/HE/fGcqYX59CrpNFV584u9l8p/t5BIN7wRnHk0mx8Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iJyQwhZJs46i1XKW/wpy2EY0vrhrEiDYRytPGST34m7zm8u5KB/4YfFTamU//VMoA 8NJnuZZH8Wv3x4jluzelWX+UbSt4fRj392UFjRXva0JTrKqFlzeGqEG3gI008wfqyi UzXOM+Llr8b8bQmob9ZyoFybwPO5YsGP43whskxc= From: paulmck@kernel.org To: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, kernel-team@fb.com, mingo@kernel.org Cc: elver@google.com, andreyknvl@google.com, glider@google.com, dvyukov@google.com, cai@lca.pw, boqun.feng@gmail.com, "Paul E . McKenney" Subject: [PATCH kcsan 13/19] kcsan: Simplify constant string handling Date: Mon, 31 Aug 2020 11:17:59 -0700 Message-Id: <20200831181805.1833-13-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831181715.GA1530@paulmck-ThinkPad-P72> References: <20200831181715.GA1530@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marco Elver Simplify checking prefixes and length calculation of constant strings. For the former, the kernel provides str_has_prefix(), and the latter we should just use strlen("..") because GCC and Clang have optimizations that optimize these into constants. No functional change intended. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney --- kernel/kcsan/debugfs.c | 8 ++++---- kernel/kcsan/report.c | 4 ++-- 2 files changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c index 3a9566a..116bdd8 100644 --- a/kernel/kcsan/debugfs.c +++ b/kernel/kcsan/debugfs.c @@ -300,16 +300,16 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o WRITE_ONCE(kcsan_enabled, true); } else if (!strcmp(arg, "off")) { WRITE_ONCE(kcsan_enabled, false); - } else if (!strncmp(arg, "microbench=", sizeof("microbench=") - 1)) { + } else if (str_has_prefix(arg, "microbench=")) { unsigned long iters; - if (kstrtoul(&arg[sizeof("microbench=") - 1], 0, &iters)) + if (kstrtoul(&arg[strlen("microbench=")], 0, &iters)) return -EINVAL; microbenchmark(iters); - } else if (!strncmp(arg, "test=", sizeof("test=") - 1)) { + } else if (str_has_prefix(arg, "test=")) { unsigned long iters; - if (kstrtoul(&arg[sizeof("test=") - 1], 0, &iters)) + if (kstrtoul(&arg[strlen("test=")], 0, &iters)) return -EINVAL; test_thread(iters); } else if (!strcmp(arg, "whitelist")) { diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c index 3e83a69..bf1d594 100644 --- a/kernel/kcsan/report.c +++ b/kernel/kcsan/report.c @@ -279,8 +279,8 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries cur = strnstr(buf, "kcsan_", len); if (cur) { - cur += sizeof("kcsan_") - 1; - if (strncmp(cur, "test", sizeof("test") - 1)) + cur += strlen("kcsan_"); + if (!str_has_prefix(cur, "test")) continue; /* KCSAN runtime function. */ /* KCSAN related test. */ } -- 2.9.5