power_supply: Change ownership from driver to core

Change the ownership of power_supply structure from each driver
implementing the class to the power supply core.

The patch changes power_supply_register() function thus all drivers
implementing power supply class are adjusted.

Each driver provides the implementation of power supply. However it
should not be the owner of power supply class instance because it is
exposed by core to other subsystems with power_supply_get_by_name().
These other subsystems have no knowledge when the driver will unregister
the power supply. This leads to several issues when driver is unbound -
mostly because user of power supply accesses freed memory.

Instead let the core own the instance of struct 'power_supply'.  Other
users of this power supply will still access valid memory because it
will be freed when device reference count reaches 0. Currently this
means "it will leak" but power_supply_put() call in next patches will
solve it.

This solves invalid memory references 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' call is executed in invalid context because the driver was
unbound and struct 'power_supply' memory was freed.

This could be observed easily with charger manager driver (here compiled
with max17040 fuel gauge):

$ cat /sys/devices/virtual/power_supply/cm-battery/capacity &
$ echo "1-0036" > /sys/bus/i2c/drivers/max17040/unbind
[   55.725123] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[   55.732584] pgd = d98d4000
[   55.734060] [00000000] *pgd=5afa2831, *pte=00000000, *ppte=00000000
[   55.740318] Internal error: Oops: 80000007 [#1] PREEMPT SMP ARM
[   55.746210] Modules linked in:
[   55.749259] CPU: 1 PID: 2936 Comm: cat Tainted: G        W       3.19.0-rc1-next-20141226-00048-gf79f475f3c44-dirty #1496
[   55.760190] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[   55.766270] task: d9b76f00 ti: daf54000 task.ti: daf54000
[   55.771647] PC is at 0x0
[   55.774182] LR is at charger_get_property+0x2f4/0x36c
[   55.779201] pc : [<00000000>]    lr : [<c034b0b4>]    psr: 60000013
[   55.779201] sp : daf55e90  ip : 00000003  fp : 00000000
[   55.790657] r10: 00000000  r9 : c06e2878  r8 : d9b26c68
[   55.795865] r7 : dad81610  r6 : daec7410  r5 : daf55ebc  r4 : 00000000
[   55.802367] r3 : 00000000  r2 : daf55ebc  r1 : 0000002a  r0 : d9b26c68
[   55.808879] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[   55.815994] Control: 10c5387d  Table: 598d406a  DAC: 00000015
[   55.821723] Process cat (pid: 2936, stack limit = 0xdaf54210)
[   55.827451] Stack: (0xdaf55e90 to 0xdaf56000)
[   55.831795] 5e80:                                     60000013 c01459c4 0000002a c06f8ef8
[   55.839956] 5ea0: db651000 c06f8ef8 daebac00 c04cb668 daebac08 c0346864 00000000 c01459c4
[   55.848115] 5ec0: d99eaa80 c06f8ef8 00000fff 00001000 db651000 c027f25c c027f240 d99eaa80
[   55.856274] 5ee0: d9a06c00 c0146218 daf55f18 00001000 d99eaa80 db4c18c0 00000001 00000001
[   55.864468] 5f00: daf55f80 c0144c78 c0144c54 c0107f90 00015000 d99eaab0 00000000 00000000
[   55.872603] 5f20: 000051c7 00000000 db4c18c0 c04a9370 00015000 00001000 daf55f80 00001000
[   55.880763] 5f40: daf54000 00015000 00000000 c00e53dc db4c18c0 c00e548c 0000000d 00008124
[   55.888937] 5f60: 00000001 00000000 00000000 db4c18c0 db4c18c0 00001000 00015000 c00e5550
[   55.897099] 5f80: 00000000 00000000 00001000 00001000 00015000 00000003 00000003 c000f364
[   55.905239] 5fa0: 00000000 c000f1a0 00001000 00015000 00000003 00015000 00001000 0001333c
[   55.913399] 5fc0: 00001000 00015000 00000003 00000003 00000002 00000000 00000000 00000000
[   55.921560] 5fe0: 7fffe000 be999850 0000a225 b6f3c19c 60000010 00000003 00000000 00000000
[   55.929744] [<c034b0b4>] (charger_get_property) from [<c0346864>] (power_supply_show_property+0x48/0x20c)
[   55.939286] [<c0346864>] (power_supply_show_property) from [<c027f25c>] (dev_attr_show+0x1c/0x48)
[   55.948130] [<c027f25c>] (dev_attr_show) from [<c0146218>] (sysfs_kf_seq_show+0x84/0x104)
[   55.956298] [<c0146218>] (sysfs_kf_seq_show) from [<c0144c78>] (kernfs_seq_show+0x24/0x28)
[   55.964536] [<c0144c78>] (kernfs_seq_show) from [<c0107f90>] (seq_read+0x1b0/0x484)
[   55.972172] [<c0107f90>] (seq_read) from [<c00e53dc>] (__vfs_read+0x18/0x4c)
[   55.979188] [<c00e53dc>] (__vfs_read) from [<c00e548c>] (vfs_read+0x7c/0x100)
[   55.986304] [<c00e548c>] (vfs_read) from [<c00e5550>] (SyS_read+0x40/0x8c)
[   55.993164] [<c00e5550>] (SyS_read) from [<c000f1a0>] (ret_fast_syscall+0x0/0x48)
[   56.000626] Code: bad PC value
[   56.011652] ---[ end trace 7b64343fbdae8ef1 ]---

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

[for the nvec part]
Reviewed-by: Marc Dietrich <marvin24@gmx.de>

[for compal-laptop.c]
Acked-by: Darren Hart <dvhart@linux.intel.com>

[for the mfd part]
Acked-by: Lee Jones <lee.jones@linaro.org>

[for the hid part]
Acked-by: Jiri Kosina <jkosina@suse.cz>

[for the acpi part]
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Signed-off-by: Sebastian Reichel <sre@kernel.org>

1 files changed, 28 insertions, 23 deletions

diff --git a/drivers/power/ltc2941-battery-gauge.c b/drivers/power/ltc2941-battery-gauge.c
index 9bc545393ef8..daeb0860736c 100644
--- a/drivers/power/ltc2941-battery-gauge.c
+++ b/drivers/power/ltc2941-battery-gauge.c
@@ -59,7 +59,8 @@ enum ltc294x_reg {
 
 struct ltc294x_info {
 	struct i2c_client *client;	/* I2C Client pointer */
-	struct power_supply supply;	/* Supply pointer */
+	struct power_supply *supply;	/* Supply pointer */
+	struct power_supply_desc supply_desc;	/* Supply description */
 	struct delayed_work work;	/* Work scheduler */
 	int num_regs;	/* Number of registers (chip type) */
 	int id;		/* Identifier of ltc294x chip */
@@ -294,8 +295,7 @@ static int ltc294x_get_property(struct power_supply *psy,
 				enum power_supply_property prop,
 				union power_supply_propval *val)
 {
-	struct ltc294x_info *info =
-		container_of(psy, struct ltc294x_info, supply);
+	struct ltc294x_info *info = power_supply_get_drvdata(psy);
 
 	switch (prop) {
 	case POWER_SUPPLY_PROP_CHARGE_NOW:
@@ -317,8 +317,7 @@ static int ltc294x_set_property(struct power_supply *psy,
 	enum power_supply_property psp,
 	const union power_supply_propval *val)
 {
-	struct ltc294x_info *info =
-		container_of(psy, struct ltc294x_info, supply);
+	struct ltc294x_info *info = power_supply_get_drvdata(psy);
 
 	switch (psp) {
 	case POWER_SUPPLY_PROP_CHARGE_NOW:
@@ -345,7 +344,7 @@ static void ltc294x_update(struct ltc294x_info *info)
 
 	if (charge != info->charge) {
 		info->charge = charge;
-		power_supply_changed(&info->supply);
+		power_supply_changed(info->supply);
 	}
 }
 
@@ -371,8 +370,8 @@ static int ltc294x_i2c_remove(struct i2c_client *client)
 	struct ltc294x_info *info = i2c_get_clientdata(client);
 
 	cancel_delayed_work(&info->work);
-	power_supply_unregister(&info->supply);
-	kfree(info->supply.name);
+	power_supply_unregister(info->supply);
+	kfree(info->supply_desc.name);
 	mutex_lock(&ltc294x_lock);
 	idr_remove(&ltc294x_id, info->id);
 	mutex_unlock(&ltc294x_lock);
@@ -382,6 +381,7 @@ static int ltc294x_i2c_remove(struct i2c_client *client)
 static int ltc294x_i2c_probe(struct i2c_client *client,
 	const struct i2c_device_id *id)
 {
+	struct power_supply_config psy_cfg = {};
 	struct ltc294x_info *info;
 	int ret;
 	int num;
@@ -406,8 +406,9 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, info);
 
 	info->num_regs = id->driver_data;
-	info->supply.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
-	if (!info->supply.name) {
+	info->supply_desc.name = kasprintf(GFP_KERNEL, "%s-%d", client->name,
+					   num);
+	if (!info->supply_desc.name) {
 		ret = -ENOMEM;
 		goto fail_name;
 	}
@@ -446,24 +447,26 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 
 	info->client = client;
 	info->id = num;
-	info->supply.type = POWER_SUPPLY_TYPE_BATTERY;
-	info->supply.properties = ltc294x_properties;
+	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
+	info->supply_desc.properties = ltc294x_properties;
 	if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
-		info->supply.num_properties =
+		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties);
 	else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
-		info->supply.num_properties =
+		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 1;
 	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
-		info->supply.num_properties =
+		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 2;
 	else
-		info->supply.num_properties =
+		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 3;
-	info->supply.get_property = ltc294x_get_property;
-	info->supply.set_property = ltc294x_set_property;
-	info->supply.property_is_writeable = ltc294x_property_is_writeable;
-	info->supply.external_power_changed	= NULL;
+	info->supply_desc.get_property = ltc294x_get_property;
+	info->supply_desc.set_property = ltc294x_set_property;
+	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
+	info->supply_desc.external_power_changed	= NULL;
+
+	psy_cfg.drv_data = info;
 
 	INIT_DELAYED_WORK(&info->work, ltc294x_work);
 
@@ -473,9 +476,11 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 		goto fail_comm;
 	}
 
-	ret = power_supply_register(&client->dev, &info->supply, NULL);
-	if (ret) {
+	info->supply = power_supply_register(&client->dev, &info->supply_desc,
+					     &psy_cfg);
+	if (IS_ERR(info->supply)) {
 		dev_err(&client->dev, "failed to register ltc2941\n");
+		ret = PTR_ERR(info->supply);
 		goto fail_register;
 	} else {
 		schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
@@ -484,7 +489,7 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 	return 0;
 
 fail_register:
-	kfree(info->supply.name);
+	kfree(info->supply_desc.name);
 fail_comm:
 fail_name:
 fail_info: