On Mon, Nov 9, 2015 at 10:12 AM, Verma, Vishal L
<vishal.l.verma@xxxxxxxxx> wrote:
> On Sat, 2015-11-07 at 13:20 -0800, Dan Williams wrote:
>> On Sat, Nov 7, 2015 at 10:57 AM, Dan Williams <dan.j.williams@xxxxxxxx
>> m> wrote:
>> > Rafael, awaiting your ack...
>> >
>> > Vishal, one thing I'll fix up on applying...
>> >
>> > On Tue, Oct 27, 2015 at 3:58 PM, Vishal Verma <vishal.l.verma@intel.
>> > com> wrote:
>> > > Add a .notify callback to the acpi_nfit_driver that gets called on
>> > > a
>> > > hotplug event. From this, evaluate the _FIT ACPI method which
>> > > returns
>> > > the updated NFIT with handles for the hot-plugged NVDIMM.
>> > >
>> > > Iterate over the new NFIT, and add any new tables found, and
>> > > register/enable the corresponding regions.
>> > >
>> > > In the nfit test framework, after normal initialization, update
>> > > the NFIT
>> > > with a new hot-plugged NVDIMM, and directly call into the driver
>> > > to
>> > > update its view of the available regions.
>> > >
>> > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
>> > > Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>> > > Cc: Toshi Kani <toshi.kani@xxxxxxx>
>> > > Cc: Elliott, Robert <elliott@xxxxxxx>
>> > > Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
>> > > Cc: <linux-acpi@xxxxxxxxxxxxxxx>
>> > > Cc: <linux-nvdimm@xxxxxxxxxxxx>
>> > > Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
>> > [..]
>> >
>> > > +static int acpi_nfit_add(struct acpi_device *adev)
>> > > +{
>> > > + struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
>> > > + struct acpi_nfit_desc *acpi_desc;
>> > > + struct device *dev = &adev->dev;
>> > > + struct acpi_table_header *tbl;
>> > > + acpi_status status = AE_OK;
>> > > + acpi_size sz;
>> > > + int rc = 0;
>> > > +
>> > > + device_lock(dev);
>> >
>> > The device is already locked by the time we reach this point. The
>> > unit tests don't trip this path which might be why this wasn't seen
>> > earlier.
>>
>> The lockup call trace if you're interested:
>>
>> dracut:/# [ 376.030455] INFO: task systemd-udevd:278 blocked for more
>> than 120 seconds.
>> [ 376.032561] Tainted: G O 4.3.0-rc6+ #1747
>> [ 376.034376] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
>> disables this message.
>> [ 376.036704] systemd-udevd D 0000000000000000 0 278 262
>> 0x00000004
>> [ 376.039758] ffff880352a0ba60 0000000000000092 ffff880352a0ba88
>> ffff880361e57b98
>> [ 376.043779] ffff88035f150000 ffff880352ea5dc0 ffff880352a0c000
>> 0000000000000246
>> [ 376.047800] ffff880359a43148 ffff880352ea5dc0 00000000ffffffff
>> ffff880352a0ba78
>> [ 376.051821] Call Trace:
>> [ 376.052882] [<ffffffff818e8b43>] schedule+0x33/0x80
>> [ 376.054527] [<ffffffff818e8eae>]
>> schedule_preempt_disabled+0xe/0x10
>> [ 376.056493] [<ffffffff818eaf2f>] mutex_lock_nested+0x14f/0x3a0
>> [ 376.058361] [<ffffffffa003140e>] ? acpi_nfit_add+0x4e/0x150 [nfit]
>> [ 376.060310] [<ffffffffa003140e>] acpi_nfit_add+0x4e/0x150 [nfit]
>> [ 376.062283] [<ffffffff81584310>] ?
>> devices_kset_move_last+0x60/0x90
>> [ 376.064250] [<ffffffff814d61c0>] acpi_device_probe+0x4f/0xf5
>> [ 376.066076] [<ffffffff81588244>] driver_probe_device+0x224/0x480
>> [ 376.067983] [<ffffffff81588528>] __driver_attach+0x88/0x90
>> [ 376.069769] [<ffffffff815884a0>] ? driver_probe_device+0x480/0x480
>> [ 376.071716] [<ffffffff81585d83>] bus_for_each_dev+0x73/0xc0
>> [ 376.073522] [<ffffffff81587b9e>] driver_attach+0x1e/0x20
>> [ 376.075267] [<ffffffff815876de>] bus_add_driver+0x1ee/0x280
>> [ 376.077072] [<ffffffffa0038000>] ? 0xffffffffa0038000
>> [ 376.078757] [<ffffffff81588f10>] driver_register+0x60/0xe0
>> [ 376.080543] [<ffffffff814d6095>]
>> acpi_bus_register_driver+0x40/0x42
>> [ 376.082511] [<ffffffffa00380ce>] nfit_init+0xce/0x1000 [nfit]
>>
>>
>
> Thanks for the fixup, Dan. The change looks good - I think I got too
> reliant on lockdep not complaining - should've taken a closer look.
Unfortunately device_lock() has this by default in device_initialize():
void device_initialize(struct device *dev)
{
...
lockdep_set_novalidate_class(&dev->mutex);
...
}
...so it hides these issues by default.
--
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
