linux-kernel - Re: [PATCH] PCI: pcie: Call pm_runtime_no_callbacks() after device is registered

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Date:	Tue, 24 May 2016 10:58:57 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Bjorn Helgaas <helgaas@...nel.org>
Cc:	Valdis Kletnieks <valdis.kletnieks@...edu>,
	Lukas Wunner <lukas@...ner.de>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH] PCI: pcie: Call pm_runtime_no_callbacks() after device
 is registered

On Mon, May 23, 2016 at 02:55:00PM -0500, Bjorn Helgaas wrote:
> On Mon, May 23, 2016 at 11:11:55AM +0300, Mika Westerberg wrote:
> > Commit 0195d2813547 ("PCI: Add runtime PM support for PCIe ports") added
> > call to pm_runtime_no_callbacks() for each port service device to prevent
> > them exposing unnecessary runtime PM sysfs files. However, that function
> > tries to acquire dev->power.lock which is not yet initialized.
> > 
> > This triggers following splat:
> > 
> >  BUG: spinlock bad magic on CPU#0, swapper/0/1
> >   lock: 0xffff8801be2aa8e8, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
> >  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0+ #820
> >   0000000000000000 ffff8801beb97be0 ffffffff812cf42d 0000000000000000
> >   ffff8801be2aa8e8 ffff8801beb97c00 ffffffff8109ee58 ffff8801be2aa8e8
> >   ffff8801be2aa8e8 ffff8801beb97c30 ffffffff8109efd9 ffff8801be2aa8e8
> >  Call Trace:
> >   [<ffffffff812cf42d>] dump_stack+0x4f/0x72
> >   [<ffffffff8109ee58>] spin_dump+0x78/0xc0
> >   [<ffffffff8109efd9>] do_raw_spin_lock+0xf9/0x150
> >   [<ffffffff81674e10>] _raw_spin_lock_irq+0x20/0x30
> >   [<ffffffff813d738e>] pm_runtime_no_callbacks+0x1e/0x40
> >   [<ffffffff81322cad>] pcie_port_device_register+0x1fd/0x4e0
> >   [<ffffffff813232f8>] pcie_portdrv_probe+0x38/0xa0
> >   [<ffffffff81314fb5>] local_pci_probe+0x45/0xa0
> >   [<ffffffff81315fe0>] ? pci_match_device+0xe0/0x110
> >   [<ffffffff813163ab>] pci_device_probe+0xdb/0x130
> >   [<ffffffff813ccefc>] driver_probe_device+0x22c/0x440
> >   [<ffffffff813cd1e1>] __driver_attach+0xd1/0xf0
> >   [<ffffffff813cd110>] ? driver_probe_device+0x440/0x440
> >   [<ffffffff813caab4>] bus_for_each_dev+0x64/0xa0
> >   [<ffffffff813cc60e>] driver_attach+0x1e/0x20
> >   [<ffffffff813cc0cb>] bus_add_driver+0x1eb/0x280
> >   [<ffffffff81d36cdc>] ? pcie_port_setup+0x7c/0x7c
> >   [<ffffffff813cdb90>] driver_register+0x60/0xe0
> >   [<ffffffff813148e0>] __pci_register_driver+0x60/0x70
> >   [<ffffffff81d36d3f>] pcie_portdrv_init+0x63/0x75
> >   [<ffffffff810003db>] do_one_initcall+0xab/0x1c0
> >   [<ffffffff81cff083>] kernel_init_freeable+0x153/0x1d9
> >   [<ffffffff8166dfce>] kernel_init+0xe/0x100
> >   [<ffffffff81675612>] ret_from_fork+0x22/0x40
> >   [<ffffffff8166dfc0>] ? rest_init+0x90/0x90
> > 
> > Fix this by calling pm_runtime_no_callbacks() after device_register() just
> > like other buses, like I2C is doing already.
> > 
> > Reported-by: Valdis Kletnieks <valdis.kletnieks@...edu>
> > Tested-by: Valdis Kletnieks <valdis.kletnieks@...edu>
> > Suggested-by: Lukas Wunner <lukas@...ner.de>
> > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> 
> I think this is a bugfix for "PCI: Add runtime PM support for PCIe
> ports", so I folded this into that patch since it hasn't been merged
> yet.  Is that the right place for it?

Yes, that's right. Thanks!