From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755653Ab3IMWcC (ORCPT ); Fri, 13 Sep 2013 18:32:02 -0400 Received: from mga11.intel.com ([192.55.52.93]:44577 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755452Ab3IMWcA (ORCPT ); Fri, 13 Sep 2013 18:32:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,901,1371106800"; d="scan'208";a="401444554" Date: Fri, 13 Sep 2013 15:31:59 -0700 From: Andi Kleen To: x86@kernel.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH] jump_labels: Add WARN_ON for too early jump label use Message-ID: <20130913223159.GA22222@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I spent a few hours tracking down a regression in my TSX code, which turned out that it is not legal anymore to change jump labels before the jump label code is initialized. Add a WARN_ON() for this case. Signed-off-by: Andi Kleen diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 297a924..c6c5290 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -17,6 +17,8 @@ #ifdef HAVE_JUMP_LABEL +static bool jump_label_initialized; + /* mutex to protect coming/going of the the jump_label table */ static DEFINE_MUTEX(jump_label_mutex); @@ -58,6 +60,8 @@ static void jump_label_update(struct static_key *key, int enable); void static_key_slow_inc(struct static_key *key) { + WARN_ON(!jump_label_initialized); + if (atomic_inc_not_zero(&key->enabled)) return; @@ -76,6 +80,7 @@ EXPORT_SYMBOL_GPL(static_key_slow_inc); static void __static_key_slow_dec(struct static_key *key, unsigned long rate_limit, struct delayed_work *work) { + WARN_ON(!jump_label_initialized); if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { WARN(atomic_read(&key->enabled) < 0, "jump label: negative count!\n"); @@ -213,6 +218,7 @@ void __init jump_label_init(void) #endif } jump_label_unlock(); + jump_label_initialized = true; } #ifdef CONFIG_MODULES -- ak@linux.intel.com -- Speaking for myself only