On Tuesday, March 10, 2015 03:17:59 PM Sebastian Reichel wrote: > > --P+33d92oIH25kiaB > Content-Type: text/plain; charset=us-ascii > Content-Disposition: inline > Content-Transfer-Encoding: quoted-printable > > Hi Rafael and Len, > > On Tue, Mar 10, 2015 at 09:27:17AM +0100, Krzysztof Kozlowski wrote: > > Change the ownership of power_supply structure from each driver > > implementing the class to the power supply core. > >=20 > > The patch changes power_supply_register() function thus all drivers > > implementing power supply class are adjusted. > >=20 > > 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. > >=20 > > 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. > >=20 > > This solves invalid memory references in following race condition > > scenario: > >=20 > > Thread 1: charger manager > > Thread 2: power supply driver, used by charger manager > >=20 > > THREAD 1 (charger manager) THREAD 2 (power supply driver) > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= > =3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > psy =3D power_supply_get_by_name() > > Driver unbind, .remove > > power_supply_unregister() > > Device fully removed > > psy->get_property() > >=20 > > The 'get_property' call is executed in invalid context because the driver= > was > > unbound and struct 'power_supply' memory was freed. > >=20 > > This could be observed easily with charger manager driver (here compiled > > with max17040 fuel gauge): > >=20 > > $ 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 virtua= > l address 00000000 > > [ 55.732584] pgd =3D d98d4000 > > [ 55.734060] [00000000] *pgd=3D5afa2831, *pte=3D00000000, *ppte=3D00000= > 000 > > [ 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 Segme= > nt user > > [ 55.815994] Control: 10c5387d Table: 598d406a DAC: 00000015 > > [ 55.821723] Process cat (pid: 2936, stack limit =3D 0xdaf54210) > > [ 55.827451] Stack: (0xdaf55e90 to 0xdaf56000) > > [ 55.831795] 5e80: 60000013 c01459c= > 4 0000002a c06f8ef8 > > [ 55.839956] 5ea0: db651000 c06f8ef8 daebac00 c04cb668 daebac08 c034686= > 4 00000000 c01459c4 > > [ 55.848115] 5ec0: d99eaa80 c06f8ef8 00000fff 00001000 db651000 c027f25= > c c027f240 d99eaa80 > > [ 55.856274] 5ee0: d9a06c00 c0146218 daf55f18 00001000 d99eaa80 db4c18c= > 0 00000001 00000001 > > [ 55.864468] 5f00: daf55f80 c0144c78 c0144c54 c0107f90 00015000 d99eaab= > 0 00000000 00000000 > > [ 55.872603] 5f20: 000051c7 00000000 db4c18c0 c04a9370 00015000 0000100= > 0 daf55f80 00001000 > > [ 55.880763] 5f40: daf54000 00015000 00000000 c00e53dc db4c18c0 c00e548= > c 0000000d 00008124 > > [ 55.888937] 5f60: 00000001 00000000 00000000 db4c18c0 db4c18c0 0000100= > 0 00015000 c00e5550 > > [ 55.897099] 5f80: 00000000 00000000 00001000 00001000 00015000 0000000= > 3 00000003 c000f364 > > [ 55.905239] 5fa0: 00000000 c000f1a0 00001000 00015000 00000003 0001500= > 0 00001000 0001333c > > [ 55.913399] 5fc0: 00001000 00015000 00000003 00000003 00000002 0000000= > 0 00000000 00000000 > > [ 55.921560] 5fe0: 7fffe000 be999850 0000a225 b6f3c19c 60000010 0000000= > 3 00000000 00000000 > > [ 55.929744] [<c034b0b4>] (charger_get_property) from [<c0346864>] (pow= > er_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_s= > eq_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+0x40/0= > x8c) > > [ 55.993164] [<c00e5550>] (SyS_read) from [<c000f1a0>] (ret_fast_syscal= > l+0x0/0x48) > > [ 56.000626] Code: bad PC value > > [ 56.011652] ---[ end trace 7b64343fbdae8ef1 ]--- > >=20 > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> > > Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> > >=20 > > [for the nvec part] > > Reviewed-by: Marc Dietrich <marvin24@xxxxxx> > >=20 > > [for compal-laptop.c] > > Acked-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx> > >=20 > > [for the mfd part] > > Acked-by: Lee Jones <lee.jones@xxxxxxxxxx> > > --- > > [...] > > drivers/acpi/ac.c | 32 ++-- > > drivers/acpi/battery.c | 55 ++++--- > > drivers/acpi/sbs.c | 68 +++++---- > > [...] > > 82 files changed, 2296 insertions(+), 1839 deletions(-) > > I would like to merge this patch via power-supply tree. Can you > please provide your Acked-By? I need more time to review this, sorry. Also this patch was killed by spam filters on vger and in GMail, so I suppose some people who need to see it are not able to. Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
