From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60239 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932933AbcECA0i (ORCPT ); Mon, 2 May 2016 20:26:38 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Geert Uytterhoeven , Arnd Bergmann , Mark Brown , Guenter Roeck Subject: [PATCH 4.4 113/163] regulator: core: fix regulator_lock_supply regression Date: Mon, 2 May 2016 17:12:21 -0700 Message-Id: <20160503000512.206904837@linuxfoundation.org> In-Reply-To: <20160503000508.556845508@linuxfoundation.org> References: <20160503000508.556845508@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Arnd Bergmann commit bb41897e38c53458a88b271f2fbcd905ee1f9584 upstream. As noticed by Geert Uytterhoeven, my patch to avoid a harmless build warning in regulator_lock_supply() was total crap and introduced a real bug: > [ BUG: bad unlock balance detected! ] > kworker/u4:0/6 is trying to release lock (&rdev->mutex) at: > [] regulator_set_voltage+0x38/0x50 we still lock the regulator supplies, but not the actual regulators, so we are missing a lock, and the unlock is unbalanced. This rectifies it by first locking the regulator device itself before using the same loop as before to lock its supplies. Reported-by: Geert Uytterhoeven Signed-off-by: Arnd Bergmann Fixes: 716fec9d1965 ("[SUBMITTED] regulator: core: avoid unused variable warning") Signed-off-by: Mark Brown Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman --- drivers/regulator/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -140,7 +140,8 @@ static void regulator_lock_supply(struct { int i; - for (i = 0; rdev->supply; rdev = rdev->supply->rdev, i++) + mutex_lock(&rdev->mutex); + for (i = 1; rdev->supply; rdev = rdev->supply->rdev, i++) mutex_lock_nested(&rdev->mutex, i); }