From: Pavel Machek <pavel@ucw.cz>
To: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Samuel Ortiz <sameo@linux.intel.com>,
Lee Jones <lee.jones@linaro.org>,
Sebastian Reichel <sre@kernel.org>,
Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>,
David Woodhouse <dwmw2@infradead.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Anton Vorontsov <anton@enomsg.org>,
Guenter Roeck <linux@roeck-us.net>,
Myungjoo Ham <myungjoo.ham@samsung.com>,
Jonghwa Lee <jonghwa3.lee@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [PATCH 1/8] power_supply: Add API for safe access of power supply function attrs
Date: Wed, 15 Oct 2014 12:30:36 +0200 [thread overview]
Message-ID: <20141015103036.GA14266@amd> (raw)
In-Reply-To: <1413289246-31650-2-git-send-email-k.kozlowski@samsung.com>
On Tue 2014-10-14 14:20:39, Krzysztof Kozlowski wrote:
> Add simple wrappers for accessing power supply's function attributes:
> - get_property -> power_supply_get_property
> - set_property -> power_supply_set_property
> - property_is_writeable -> power_supply_property_is_writeable
> - external_power_changed -> power_supply_external_power_changed
> - set_charged -> power_supply_set_charged
>
> This API adds a safe way of accessing a power supply from another
> driver. Particularly it solves invalid memory references (and lockup) in
> following race condition scenario:
>
> Thread 1: charger manager
> Thread 2: power supply driver, used by charger manager
>
> THREAD 1 (charger manager) THREAD 2 (power supply driver)
> ========================== ==============================
> psy = power_supply_get_by_name()
> Driver unbind, .remove
> power_supply_unregister
> Device fully removed
> psy->get_property()
>
> The 'get_property' callback is still valid and leads to actual calling of
> Thread2->get_property() but now in invalid context because the driver was
> unbound.
>
> This could be observed easily with charger manager driver (here compiled
> with max17042 fuel gauge):
> $ echo "12-0036" > /sys/bus/i2c/drivers/max17042/unbind
> $ cat /sys/devices/virtual/power_supply/battery/temp
> [ 240.505998] INFO: task cat:1394 blocked for more than 120 seconds.
> [ 240.510762] Not tainted 3.17.0-next-20141007-00028-ge60b6dd79570-dirty #183
> [ 240.518208] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 240.526025] cat D c0469548 0 1394 1 0x00000000
> [ 240.532384] [<c0469548>] (__schedule) from [<c0469d54>] (schedule_preempt_disabled+0x14/0x20)
> [ 240.540885] [<c0469d54>] (schedule_preempt_disabled) from [<c046af20>] (mutex_lock_nested+0x1bc/0x458)
> [ 240.550171] [<c046af20>] (mutex_lock_nested) from [<c0287a98>] (regmap_read+0x30/0x60)
> [ 240.558079] [<c0287a98>] (regmap_read) from [<c032238c>] (max17042_get_property+0x2e8/0x350)
> [ 240.566490] [<c032238c>] (max17042_get_property) from [<c0324b60>] (charger_get_property+0x238/0x31c)
> [ 240.575688] [<c0324b60>] (charger_get_property) from [<c0320764>] (power_supply_show_property+0x48/0x1e0)
> [ 240.585241] [<c0320764>] (power_supply_show_property) from [<c027308c>] (dev_attr_show+0x1c/0x48)
> [ 240.594100] [<c027308c>] (dev_attr_show) from [<c0141fb0>] (sysfs_kf_seq_show+0x84/0x104)
> [ 240.602251] [<c0141fb0>] (sysfs_kf_seq_show) from [<c0140b18>] (kernfs_seq_show+0x24/0x28)
> [ 240.610497] [<c0140b18>] (kernfs_seq_show) from [<c0104574>] (seq_read+0x1b0/0x484)
> [ 240.618138] [<c0104574>] (seq_read) from [<c00e1e24>] (vfs_read+0x88/0x144)
> [ 240.625127] [<c00e1e24>] (vfs_read) from [<c00e1f20>] (SyS_read+0x40/0x8c)
> [ 240.631941] [<c00e1f20>] (SyS_read) from [<c000e760>] (ret_fast_syscall+0x0/0x48)
>
> Or:
> [ 17.277605] Division by zero in kernel.
> [ 17.280043] CPU: 2 PID: 1384 Comm: cat Not tainted 3.17.0-next-20141007-00028-ge60b6dd79570-dirty #181
> [ 17.289348] [<c00140f0>] (unwind_backtrace) from [<c0011228>] (show_stack+0x10/0x14)
> [ 17.297055] [<c0011228>] (show_stack) from [<c04680d0>] (dump_stack+0x70/0xbc)
> [ 17.304264] [<c04680d0>] (dump_stack) from [<c01f7a28>] (Ldiv0+0x8/0x10)
> [ 17.310933] [<c01f7a28>] (Ldiv0) from [<c01f79f8>] (__aeabi_uidivmod+0x8/0x18)
> [ 17.318132] [<c01f79f8>] (__aeabi_uidivmod) from [<c0287a84>] (regmap_read+0x1c/0x60)
> [ 17.325956] [<c0287a84>] (regmap_read) from [<c0322260>] (max17042_get_property+0x1bc/0x350)
> [ 17.334361] [<c0322260>] (max17042_get_property) from [<c0324734>] (charger_get_property+0x198/0x328)
> [ 17.343560] [<c0324734>] (charger_get_property) from [<c0320764>] (power_supply_show_property+0x48/0x1e0)
> [ 17.353108] [<c0320764>] (power_supply_show_property) from [<c03209d4>] (power_supply_uevent+0x9c/0x1c4)
> [ 17.362575] [<c03209d4>] (power_supply_uevent) from [<c02745d0>] (dev_uevent+0xb8/0x1c8)
> [ 17.370639] [<c02745d0>] (dev_uevent) from [<c0272c4c>] (uevent_show+0xa8/0x104)
> [ 17.378015] [<c0272c4c>] (uevent_show) from [<c027308c>] (dev_attr_show+0x1c/0x48)
> [ 17.385579] [<c027308c>] (dev_attr_show) from [<c0141fb0>] (sysfs_kf_seq_show+0x84/0x104)
> [ 17.393731] [<c0141fb0>] (sysfs_kf_seq_show) from [<c0140b18>] (kernfs_seq_show+0x24/0x28)
> [ 17.401979] [<c0140b18>] (kernfs_seq_show) from [<c0104574>] (seq_read+0x1b0/0x484)
> [ 17.409619] [<c0104574>] (seq_read) from [<c00e1e24>] (vfs_read+0x88/0x144)
> [ 17.416557] [<c00e1e24>] (vfs_read) from [<c00e1f20>] (SyS_read+0x40/0x8c)
> [ 17.423416] [<c00e1f20>] (SyS_read) from [<c000e760>] (ret_fast_syscall+0x0/0x48)
> [ 17.430880] power_supply battery: driver failed to report `voltage_now' property: -22
>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
WARNING: multiple messages have this Message-ID (diff)
From: pavel@ucw.cz (Pavel Machek)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/8] power_supply: Add API for safe access of power supply function attrs
Date: Wed, 15 Oct 2014 12:30:36 +0200 [thread overview]
Message-ID: <20141015103036.GA14266@amd> (raw)
In-Reply-To: <1413289246-31650-2-git-send-email-k.kozlowski@samsung.com>
On Tue 2014-10-14 14:20:39, Krzysztof Kozlowski wrote:
> Add simple wrappers for accessing power supply's function attributes:
> - get_property -> power_supply_get_property
> - set_property -> power_supply_set_property
> - property_is_writeable -> power_supply_property_is_writeable
> - external_power_changed -> power_supply_external_power_changed
> - set_charged -> power_supply_set_charged
>
> This API adds a safe way of accessing a power supply from another
> driver. Particularly it solves invalid memory references (and lockup) in
> following race condition scenario:
>
> Thread 1: charger manager
> Thread 2: power supply driver, used by charger manager
>
> THREAD 1 (charger manager) THREAD 2 (power supply driver)
> ========================== ==============================
> psy = power_supply_get_by_name()
> Driver unbind, .remove
> power_supply_unregister
> Device fully removed
> psy->get_property()
>
> The 'get_property' callback is still valid and leads to actual calling of
> Thread2->get_property() but now in invalid context because the driver was
> unbound.
>
> This could be observed easily with charger manager driver (here compiled
> with max17042 fuel gauge):
> $ echo "12-0036" > /sys/bus/i2c/drivers/max17042/unbind
> $ cat /sys/devices/virtual/power_supply/battery/temp
> [ 240.505998] INFO: task cat:1394 blocked for more than 120 seconds.
> [ 240.510762] Not tainted 3.17.0-next-20141007-00028-ge60b6dd79570-dirty #183
> [ 240.518208] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 240.526025] cat D c0469548 0 1394 1 0x00000000
> [ 240.532384] [<c0469548>] (__schedule) from [<c0469d54>] (schedule_preempt_disabled+0x14/0x20)
> [ 240.540885] [<c0469d54>] (schedule_preempt_disabled) from [<c046af20>] (mutex_lock_nested+0x1bc/0x458)
> [ 240.550171] [<c046af20>] (mutex_lock_nested) from [<c0287a98>] (regmap_read+0x30/0x60)
> [ 240.558079] [<c0287a98>] (regmap_read) from [<c032238c>] (max17042_get_property+0x2e8/0x350)
> [ 240.566490] [<c032238c>] (max17042_get_property) from [<c0324b60>] (charger_get_property+0x238/0x31c)
> [ 240.575688] [<c0324b60>] (charger_get_property) from [<c0320764>] (power_supply_show_property+0x48/0x1e0)
> [ 240.585241] [<c0320764>] (power_supply_show_property) from [<c027308c>] (dev_attr_show+0x1c/0x48)
> [ 240.594100] [<c027308c>] (dev_attr_show) from [<c0141fb0>] (sysfs_kf_seq_show+0x84/0x104)
> [ 240.602251] [<c0141fb0>] (sysfs_kf_seq_show) from [<c0140b18>] (kernfs_seq_show+0x24/0x28)
> [ 240.610497] [<c0140b18>] (kernfs_seq_show) from [<c0104574>] (seq_read+0x1b0/0x484)
> [ 240.618138] [<c0104574>] (seq_read) from [<c00e1e24>] (vfs_read+0x88/0x144)
> [ 240.625127] [<c00e1e24>] (vfs_read) from [<c00e1f20>] (SyS_read+0x40/0x8c)
> [ 240.631941] [<c00e1f20>] (SyS_read) from [<c000e760>] (ret_fast_syscall+0x0/0x48)
>
> Or:
> [ 17.277605] Division by zero in kernel.
> [ 17.280043] CPU: 2 PID: 1384 Comm: cat Not tainted 3.17.0-next-20141007-00028-ge60b6dd79570-dirty #181
> [ 17.289348] [<c00140f0>] (unwind_backtrace) from [<c0011228>] (show_stack+0x10/0x14)
> [ 17.297055] [<c0011228>] (show_stack) from [<c04680d0>] (dump_stack+0x70/0xbc)
> [ 17.304264] [<c04680d0>] (dump_stack) from [<c01f7a28>] (Ldiv0+0x8/0x10)
> [ 17.310933] [<c01f7a28>] (Ldiv0) from [<c01f79f8>] (__aeabi_uidivmod+0x8/0x18)
> [ 17.318132] [<c01f79f8>] (__aeabi_uidivmod) from [<c0287a84>] (regmap_read+0x1c/0x60)
> [ 17.325956] [<c0287a84>] (regmap_read) from [<c0322260>] (max17042_get_property+0x1bc/0x350)
> [ 17.334361] [<c0322260>] (max17042_get_property) from [<c0324734>] (charger_get_property+0x198/0x328)
> [ 17.343560] [<c0324734>] (charger_get_property) from [<c0320764>] (power_supply_show_property+0x48/0x1e0)
> [ 17.353108] [<c0320764>] (power_supply_show_property) from [<c03209d4>] (power_supply_uevent+0x9c/0x1c4)
> [ 17.362575] [<c03209d4>] (power_supply_uevent) from [<c02745d0>] (dev_uevent+0xb8/0x1c8)
> [ 17.370639] [<c02745d0>] (dev_uevent) from [<c0272c4c>] (uevent_show+0xa8/0x104)
> [ 17.378015] [<c0272c4c>] (uevent_show) from [<c027308c>] (dev_attr_show+0x1c/0x48)
> [ 17.385579] [<c027308c>] (dev_attr_show) from [<c0141fb0>] (sysfs_kf_seq_show+0x84/0x104)
> [ 17.393731] [<c0141fb0>] (sysfs_kf_seq_show) from [<c0140b18>] (kernfs_seq_show+0x24/0x28)
> [ 17.401979] [<c0140b18>] (kernfs_seq_show) from [<c0104574>] (seq_read+0x1b0/0x484)
> [ 17.409619] [<c0104574>] (seq_read) from [<c00e1e24>] (vfs_read+0x88/0x144)
> [ 17.416557] [<c00e1e24>] (vfs_read) from [<c00e1f20>] (SyS_read+0x40/0x8c)
> [ 17.423416] [<c00e1f20>] (SyS_read) from [<c000e760>] (ret_fast_syscall+0x0/0x48)
> [ 17.430880] power_supply battery: driver failed to report `voltage_now' property: -22
>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2014-10-15 10:30 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-14 12:20 [PATCH 0/8] power_supply: Add API for safe access of get_property-like function attrs Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-14 12:20 ` [PATCH 1/8] power_supply: Add API for safe access of power supply " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-15 10:30 ` Pavel Machek [this message]
2014-10-15 10:30 ` Pavel Machek
2014-10-14 12:20 ` [PATCH 2/8] power_supply: sysfs: Use power_supply_*() API for accessing " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-15 10:32 ` Pavel Machek
2014-10-15 10:32 ` Pavel Machek
2014-10-15 10:49 ` Krzysztof Kozlowski
2014-10-15 10:49 ` Krzysztof Kozlowski
2014-10-15 12:19 ` Pavel Machek
2014-10-15 12:19 ` Pavel Machek
2014-10-14 12:20 ` [PATCH 3/8] power: 88pm860x_charger: " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-15 10:33 ` Pavel Machek
2014-10-15 10:33 ` Pavel Machek
2014-10-14 12:20 ` [PATCH 4/8] power: ab8500: " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-28 9:58 ` Linus Walleij
2014-10-28 9:58 ` Linus Walleij
2014-10-14 12:20 ` [PATCH 5/8] mfd: " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-15 9:07 ` Lee Jones
2014-10-15 9:07 ` Lee Jones
2014-10-14 12:20 ` [PATCH 6/8] power: apm_power: " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-14 12:20 ` [PATCH 7/8] power: bq2415x_charger: " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-14 12:20 ` [PATCH 8/8] power: charger-manager: " Krzysztof Kozlowski
2014-10-14 12:20 ` Krzysztof Kozlowski
2014-10-15 2:22 ` [PATCH 0/8] power_supply: Add API for safe access of get_property-like " jonghwa3.lee
2014-10-15 2:22 ` jonghwa3.lee at samsung.com
2014-10-15 10:35 ` Pavel Machek
2014-10-15 10:35 ` Pavel Machek
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