From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932801AbcFHGfg (ORCPT ); Wed, 8 Jun 2016 02:35:36 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:53547 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753471AbcFHGfb (ORCPT ); Wed, 8 Jun 2016 02:35:31 -0400 X-AuditID: cbfec7f4-f796c6d000001486-09-5757bcafd827 Subject: Re: [PATCH v3] power_supply: power_supply_read_temp only if use_cnt > 0 To: Rhyland Klein , Sebastian Reichel , Dmitry Eremin-Solenikov , David Woodhouse References: <1465331163-16884-1-git-send-email-rklein@nvidia.com> Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Jon Hunter , stable@vger.kernel.org From: Krzysztof Kozlowski Message-id: <5757BCAD.4060101@samsung.com> Date: Wed, 08 Jun 2016 08:35:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-version: 1.0 In-reply-to: <1465331163-16884-1-git-send-email-rklein@nvidia.com> Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrCLMWRmVeSWpSXmKPExsVy+t/xy7rr94SHGzy8J2kx6cl7ZouJKycz W7TMWsRi8fqFocXlXXPYLD73HmG0WHZ8NavF6d0lFgs2PmJ04PTYOesuu8fmFVoem1Z1snn0 Nr9j8+jbsorR4/MmuQC2KC6blNSczLLUIn27BK6MX1+eMRacUK1YsuUKSwPjGrkuRk4OCQET iQ9rv7FC2GISF+6tZwOxhQSWMkqcXxIGYT8Dsr+LgNjCAgES7x8dZ+9i5OIQEVjCKPFzRyNj FyMHUJGjRPPCRJAaZoFyiTvn21hAbDYBY4nNy5eAzeQV0JI4+OUvmM0ioCrRcPY+WI2oQITE rO0/mCBqBCV+TL4HFucUcJK4NqMXbDyzgJ7E/YtaEOPlJTavecs8gVFgFpKOWQhVs5BULWBk XsUomlqaXFCclJ5rqFecmFtcmpeul5yfu4kREvZfdjAuPmZ1iFGAg1GJh1fBMDxciDWxrLgy 9xCjBAezkghv8E6gEG9KYmVValF+fFFpTmrxIUZpDhYlcd65u96HCAmkJ5akZqemFqQWwWSZ ODilGhjj6mzm/9yyQa+ySvjX/qkSttfjJsrv4Y/+xJswZe3awPXTytcnzLScfEJH7+XNar0v 2rX5d5PKcyNWP5ESkmYJVy75Z+Zdf3YllwXzle+X5vZd/S76u7Ve/dk5MfEN69aqdN46JGed fLTT96Im55rFiwxdJkxLelj7Nd/x7PTAc7fnS26d/e6DEktxRqKhFnNRcSIAjd2OcHcCAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/07/2016 10:26 PM, Rhyland Klein wrote: > Change power_supply_read_temp() to use power_supply_get_property() > so that it will check the use_cnt and ensure it 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 > > Also make the same change to ps_get_max_charge_cntl_limit() and > ps_get_cur_chrage_cntl_limit() to be safe. Lastly, change the return > value of power_supply_get_property() to -EAGAIN from -ENODEV if > use_cnt <= 0. > > Fixes: 297d716f6260 ("power_supply: Change ownership from driver to core") > Cc: stable@vger.kernel.org > Signed-off-by: Rhyland Klein > --- > v3: > - Changed calls to ->get_property() to use common > power_supply_get_property() > - reworded description, added "Fixes" line > - Changed return value of power_supply_get_property() to -EAGAIN > > v2: > - Added cc stable > - changed return to -EAGAIN in case of use_cnt < 1 > - Removed WARNING > - return value check added in additional patch: > https://lkml.org/lkml/2016/6/6/706 > > drivers/power/power_supply_core.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) > > diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c > index 456987c88baa..cccc630bd68e 100644 > --- a/drivers/power/power_supply_core.c > +++ b/drivers/power/power_supply_core.c > @@ -492,7 +492,7 @@ int power_supply_get_property(struct power_supply *psy, > union power_supply_propval *val) > { > if (atomic_read(&psy->use_cnt) <= 0) > - return -ENODEV; > + return -EAGAIN; Wait, no. I was thinking of changing the return value in power_supply_read_temp() if we really want EAGAIN: ret = power_supply_get_property(...); if (ret) return -EAGAIN; On the other hand, here both return values look correct... the call can be executed too early (not very common) or too late after unbinding the driver (also kind of specific). > > return psy->desc->get_property(psy, psp, val); > } > @@ -564,12 +564,14 @@ static int power_supply_read_temp(struct thermal_zone_device *tzd, > int ret; > > WARN_ON(tzd == NULL); > + > psy = tzd->devdata; > - ret = psy->desc->get_property(psy, POWER_SUPPLY_PROP_TEMP, &val); > + ret = power_supply_get_property(psy, POWER_SUPPLY_PROP_TEMP, &val); > + if (!ret) > + return ret; I think you wanted reverse: if (ret) > > /* Convert tenths of degree Celsius to milli degree Celsius. */ > - if (!ret) > - *temp = val.intval * 100; > + *temp = val.intval * 100; > > return ret; > } > @@ -612,10 +614,12 @@ static int ps_get_max_charge_cntl_limit(struct thermal_cooling_device *tcd, > int ret; > > psy = tcd->devdata; > - ret = psy->desc->get_property(psy, > - POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX, &val); > + ret = power_supply_get_property(psy, > + POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX, &val); > if (!ret) > - *state = val.intval; > + return ret; Wait, again - why are you inverting the logic of 'ret'? BR, Krzysztof > + > + *state = val.intval; > > return ret; > } > @@ -628,10 +632,12 @@ static int ps_get_cur_chrage_cntl_limit(struct thermal_cooling_device *tcd, > int ret; > > psy = tcd->devdata; > - ret = psy->desc->get_property(psy, > - POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT, &val); > + ret = power_supply_get_property(psy, > + POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT, &val); > if (!ret) > - *state = val.intval; > + return ret; > + > + *state = val.intval; > > return ret; > } >