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>

6 files changed, 47 insertions, 30 deletions

diff --git a/include/linux/hid.h b/include/linux/hid.h
index efc7787a41a8..f94cf28e4b7c 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -514,10 +514,10 @@ struct hid_device {							/* device report descriptor */
 #ifdef CONFIG_HID_BATTERY_STRENGTH
 	/*
 	 * Power supply information for HID devices which report
-	 * battery strength. power_supply is registered iff
-	 * battery.name is non-NULL.
+	 * battery strength. power_supply was successfully registered if
+	 * battery is non-NULL.
 	 */
-	struct power_supply battery;
+	struct power_supply *battery;
 	__s32 battery_min;
 	__s32 battery_max;
 	__s32 battery_report_type;
diff --git a/include/linux/mfd/abx500/ux500_chargalg.h b/include/linux/mfd/abx500/ux500_chargalg.h
index 234c99143bf7..67703f23e7ba 100644
--- a/include/linux/mfd/abx500/ux500_chargalg.h
+++ b/include/linux/mfd/abx500/ux500_chargalg.h
@@ -9,8 +9,13 @@
 
 #include <linux/power_supply.h>
 
-#define psy_to_ux500_charger(x) container_of((x), \
-		struct ux500_charger, psy)
+/*
+ * Valid only for supplies of type:
+ * - POWER_SUPPLY_TYPE_MAINS,
+ * - POWER_SUPPLY_TYPE_USB,
+ * because only them store as drv_data pointer to struct ux500_charger.
+ */
+#define psy_to_ux500_charger(x) power_supply_get_drvdata(psy)
 
 /* Forward declaration */
 struct ux500_charger;
@@ -35,7 +40,7 @@ struct ux500_charger_ops {
  * @power_path		USB power path support
  */
 struct ux500_charger {
-	struct power_supply psy;
+	struct power_supply *psy;
 	struct ux500_charger_ops ops;
 	int max_out_volt;
 	int max_out_curr;
diff --git a/include/linux/mfd/rt5033.h b/include/linux/mfd/rt5033.h
index 010cff49a98e..6cff5cf458d2 100644
--- a/include/linux/mfd/rt5033.h
+++ b/include/linux/mfd/rt5033.h
@@ -39,7 +39,7 @@ struct rt5033_battery {
 	struct i2c_client	*client;
 	struct rt5033_dev	*rt5033;
 	struct regmap		*regmap;
-	struct power_supply	psy;
+	struct power_supply	*psy;
 };
 
 /* RT5033 charger platform data */
diff --git a/include/linux/mfd/wm8350/supply.h b/include/linux/mfd/wm8350/supply.h
index 2b9479310bbd..8dc93673e34a 100644
--- a/include/linux/mfd/wm8350/supply.h
+++ b/include/linux/mfd/wm8350/supply.h
@@ -123,9 +123,9 @@ struct wm8350_charger_policy {
 
 struct wm8350_power {
 	struct platform_device *pdev;
-	struct power_supply battery;
-	struct power_supply usb;
-	struct power_supply ac;
+	struct power_supply *battery;
+	struct power_supply *usb;
+	struct power_supply *ac;
 	struct wm8350_charger_policy *policy;
 
 	int rev_g_coeff;
diff --git a/include/linux/power/charger-manager.h b/include/linux/power/charger-manager.h
index 416ebeb6ee1e..eadf28cb2fc9 100644
--- a/include/linux/power/charger-manager.h
+++ b/include/linux/power/charger-manager.h
@@ -242,7 +242,8 @@ struct charger_manager {
 	int emergency_stop;
 
 	char psy_name_buf[PSY_NAME_MAX + 1];
-	struct power_supply charger_psy;
+	struct power_supply_desc charger_psy_desc;
+	struct power_supply *charger_psy;
 
 	u64 charging_start_time;
 	u64 charging_end_time;
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 7ae60346465f..ea15eb68f609 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -13,6 +13,7 @@
 #ifndef __LINUX_POWER_SUPPLY_H__
 #define __LINUX_POWER_SUPPLY_H__
 
+#include <linux/device.h>
 #include <linux/workqueue.h>
 #include <linux/leds.h>
 #include <linux/spinlock.h>
@@ -173,10 +174,10 @@ union power_supply_propval {
 	const char *strval;
 };
 
-struct device;
 struct device_node;
+struct power_supply;
 
-/* Power supply instance specific configuration */
+/* Run-time specific power supply configuration */
 struct power_supply_config {
 	struct device_node *of_node;
 	/* Driver private data */
@@ -186,19 +187,13 @@ struct power_supply_config {
 	size_t num_supplicants;
 };
 
-struct power_supply {
+/* Description of power supply */
+struct power_supply_desc {
 	const char *name;
 	enum power_supply_type type;
 	enum power_supply_property *properties;
 	size_t num_properties;
 
-	char **supplied_to;
-	size_t num_supplicants;
-
-	char **supplied_from;
-	size_t num_supplies;
-	struct device_node *of_node;
-
 	/*
 	 * Functions for drivers implementing power supply class.
 	 * These shouldn't be called directly by other drivers for accessing
@@ -224,12 +219,23 @@ struct power_supply {
 	bool no_thermal;
 	/* For APM emulation, think legacy userspace. */
 	int use_for_apm;
+};
+
+struct power_supply {
+	const struct power_supply_desc *desc;
+
+	char **supplied_to;
+	size_t num_supplicants;
+
+	char **supplied_from;
+	size_t num_supplies;
+	struct device_node *of_node;
 
 	/* Driver private data */
 	void *drv_data;
 
 	/* private */
-	struct device *dev;
+	struct device dev;
 	struct work_struct changed_work;
 	spinlock_t changed_lock;
 	bool changed;
@@ -303,17 +309,22 @@ extern int power_supply_set_property(struct power_supply *psy,
 extern int power_supply_property_is_writeable(struct power_supply *psy,
 					enum power_supply_property psp);
 extern void power_supply_external_power_changed(struct power_supply *psy);
-extern int power_supply_register(struct device *parent,
-				 struct power_supply *psy,
+
+extern struct power_supply *__must_check
+power_supply_register(struct device *parent,
+				 const struct power_supply_desc *desc,
 				 const struct power_supply_config *cfg);
-extern int power_supply_register_no_ws(struct device *parent,
-				 struct power_supply *psy,
+extern struct power_supply *__must_check
+power_supply_register_no_ws(struct device *parent,
+				 const struct power_supply_desc *desc,
 				 const struct power_supply_config *cfg);
-extern int devm_power_supply_register(struct device *parent,
-				 struct power_supply *psy,
+extern struct power_supply *__must_check
+devm_power_supply_register(struct device *parent,
+				 const struct power_supply_desc *desc,
 				 const struct power_supply_config *cfg);
-extern int devm_power_supply_register_no_ws(struct device *parent,
-				 struct power_supply *psy,
+extern struct power_supply *__must_check
+devm_power_supply_register_no_ws(struct device *parent,
+				 const struct power_supply_desc *desc,
 				 const struct power_supply_config *cfg);
 extern void power_supply_unregister(struct power_supply *psy);
 extern int power_supply_powers(struct power_supply *psy, struct device *dev);