From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161525AbcFGQqB (ORCPT ); Tue, 7 Jun 2016 12:46:01 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:3202 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932922AbcFGQp7 (ORCPT ); Tue, 7 Jun 2016 12:45:59 -0400 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Tue, 07 Jun 2016 09:42:51 -0700 Subject: Re: [RESEND PATCH v2] power_supply: power_supply_read_temp only if use_cnt > 0 To: Krzysztof Kozlowski , Sebastian Reichel , Dmitry Eremin-Solenikov , "David Woodhouse" References: <1465232216-12625-1-git-send-email-rklein@nvidia.com> <57567654.5060503@samsung.com> CC: , , Jon Hunter , From: Rhyland Klein Message-ID: <409802ee-74bb-b068-d5ac-85a86e0b9310@nvidia.com> Date: Tue, 7 Jun 2016 12:45:49 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <57567654.5060503@samsung.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/7/2016 3:23 AM, Krzysztof Kozlowski wrote: > On 06/06/2016 06:56 PM, Rhyland Klein wrote: >> Add check to power_supply_read_temp() to only use the power_supply >> get_property() callback if the use_cnt is > 0. The use_cnt will >> be incremented at the end of __power_supply_register, so this will >> block to case where get_property can be called before the supply >> is fully registered. This fixes the issue show in the stack below: >> >> [ 1.452598] power_supply_read_temp+0x78/0x80 >> [ 1.458680] thermal_zone_get_temp+0x5c/0x11c >> [ 1.464765] thermal_zone_device_update+0x34/0xb4 >> [ 1.471195] thermal_zone_device_register+0x87c/0x8cc >> [ 1.477974] __power_supply_register+0x364/0x424 >> [ 1.484317] power_supply_register_no_ws+0x10/0x18 >> [ 1.490833] bq27xxx_battery_setup+0x10c/0x164 >> [ 1.497003] bq27xxx_battery_i2c_probe+0xd0/0x1b0 >> [ 1.503435] i2c_device_probe+0x174/0x240 >> [ 1.509172] driver_probe_device+0x1fc/0x29c >> [ 1.515167] __driver_attach+0xa4/0xa8 >> [ 1.520643] bus_for_each_dev+0x58/0x98 >> [ 1.526204] driver_attach+0x20/0x28 >> [ 1.531505] bus_add_driver+0x1c8/0x22c >> [ 1.537067] driver_register+0x68/0x108 >> [ 1.542630] i2c_register_driver+0x38/0x7c >> [ 1.548457] bq27xxx_battery_i2c_driver_init+0x18/0x20 >> [ 1.555321] do_one_initcall+0x38/0x12c >> [ 1.560886] kernel_init_freeable+0x148/0x1ec >> [ 1.566972] kernel_init+0x10/0xfc >> [ 1.572101] ret_from_fork+0x10/0x40 >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Rhyland Klein > > And maybe: > Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core") Sure, I wasn't sure which commit this should *fix*, but that makes sense. > > >> --- >> v2: >> - Added cc stable >> - changed return to -EAGAIN in case of use_cnt < 1 >> - Removed WARNING >> - return value check added in additional patch: >> "thermal: helpers: Check return value of get_temp" >> >> drivers/power/power_supply_core.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c >> index 456987c88baa..bbd80631f31e 100644 >> --- a/drivers/power/power_supply_core.c >> +++ b/drivers/power/power_supply_core.c >> @@ -561,11 +561,15 @@ static int power_supply_read_temp(struct thermal_zone_device *tzd, >> { >> struct power_supply *psy; >> union power_supply_propval val; >> - int ret; >> + int ret = -EAGAIN; >> >> WARN_ON(tzd == NULL); >> + >> psy = tzd->devdata; >> - ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP, &val); >> + >> + if (atomic_read(&psy->use_cnt) > 0) >> + ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP, >> + &val); > > How about using just power_supply_get_property() and convert return > value to EAGAIN? I like that. I'll swap it over to use that. > > Anyway probably such check should be present also on other > get_property() calls, like thermal cooling path. I'll look around and see what else I can find. > > Best regards, > Krzysztof > -rhyland -- nvpublic