linux-kernel - Re: [PATCH] PCI: export MSI mode using attributes, not kobjects

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Date:	Thu, 12 Dec 2013 16:56:20 -0700
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Neil Horman <nhorman@...driver.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Veaceslav Falico <vfalico@...hat.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Knut Petersen <Knut_Petersen@...nline.de>,
	Ingo Molnar <mingo@...nel.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: export MSI mode using attributes, not kobjects

On Thu, Dec 12, 2013 at 4:17 PM, Yinghai Lu <yinghai@...nel.org> wrote:
> On Sat, Dec 7, 2013 at 12:41 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
>> On Wed, Nov 27, 2013 at 11:46 AM, Greg Kroah-Hartman
>> <gregkh@...uxfoundation.org> wrote:
>>> From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>>
>>> The PCI MSI sysfs code is a mess with kobjects for things that don't
>>> really need to be kobjects.  This patch creates attributes dynamically
>>> for the MSI interrupts instead of using kobjects.
>>>
>>> Note, this removes a directory from the current MSI interrupt sysfs
>>> code:
>>>
>>> old MSI kobjects:
>>> pci_device
>>>    └── msi_irqs
>>>        └── 40
>>>            └── mode
>>>
>>> new MSI attributes:
>>> pci_device
>>>    └── msi_irqs
>>>        └── 40
>>>
>>> As there was only one file "mode" with the kobject model, the interrupt
>>> number is now a file that returns the "mode" of the interrupt (msi vs.
>>> msix).
>>>
>>> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>
>> I added the acks from Neil and Veaceslav, folded in the
>> Documentation/ABI update, and applied the whole thing to my pci/misc
>> branch for v3.14.  Thanks!
>
> got:
> [   71.429735] BUG: key ffff887fcf082a58 not in .data!
> [   71.429737] ------------[ cut here ]------------
> [   71.429742] WARNING: CPU: 0 PID: 4 at kernel/locking/lockdep.c:2987 lockdep_i
> nit_map+0x127/0x5b0()
> [   71.429743] DEBUG_LOCKS_WARN_ON(1)
> [   71.429744] Modules linked in:
> [   71.429747] CPU: 0 PID: 4 Comm: kworker/0:0 Tainted: G          I  3.13.0-rc3
> -yh-01187-ge0e4e4e-dirty #45
> [   71.429757] Workqueue: events work_for_cpu_fn
> [   71.429792]  0000000000000009 ffff881fcf95da58 ffffffff82020475 ffff881fcf95d
> aa0
> [   71.429800]  ffff881fcf95da90 ffffffff81097c3d ffff887fcf082a58 ffff88dfcec1a
> d28
> [   71.429809]  0000000000000000 0000000000000000 ffff889fcf2eecd0 ffff881fcf95d
> af0
> [   71.429809] Call Trace:
> [   71.429814]  [<ffffffff82020475>] dump_stack+0x45/0x56
> [   71.429818]  [<ffffffff81097c3d>] warn_slowpath_common+0x7d/0xa0
> [   71.429822]  [<ffffffff81097cac>] warn_slowpath_fmt+0x4c/0x50
> [   71.429826]  [<ffffffff810e3d97>] lockdep_init_map+0x127/0x5b0
> [   71.429835]  [<ffffffff81242fe8>] ? sysfs_new_dirent+0x98/0x140
> [   71.429839]  [<ffffffff81242033>] sysfs_add_file_mode_ns+0x63/0xc0
> [   71.429843]  [<ffffffff8124491d>] internal_create_group+0x18d/0x260
> [   71.429853]  [<ffffffff81556345>] ? populate_msi_sysfs+0x185/0x1d0
> [   71.429857]  [<ffffffff81244a52>] sysfs_create_groups+0x42/0xa0
> [   71.429861]  [<ffffffff81556367>] populate_msi_sysfs+0x1a7/0x1d0
> [   71.429865]  [<ffffffff81556b67>] pci_enable_msi_block+0x1f7/0x2a0
> [   71.429870]  [<ffffffff81549795>] pcie_port_device_register+0x335/0x520
> [   71.429874]  [<ffffffff81549f08>] pcie_portdrv_probe+0x68/0xa0
> [   71.429883]  [<ffffffff8153cf75>] local_pci_probe+0x45/0xa0
> [   71.429887]  [<ffffffff810b0af4>] work_for_cpu_fn+0x14/0x20
> [   71.429891]  [<ffffffff810b431b>] process_one_work+0x28b/0x4a0
> [   71.429895]  [<ffffffff810b4292>] ? process_one_work+0x202/0x4a0
> [   71.429899]  [<ffffffff810b55db>] worker_thread+0x26b/0x3a0
> [   71.429903]  [<ffffffff810e262d>] ? trace_hardirqs_on+0xd/0x10
> [   71.429906]  [<ffffffff810b5370>] ? manage_workers.isra.17+0x340/0x340
> [   71.429912]  [<ffffffff810bc031>] kthread+0x111/0x120
> [   71.429919]  [<ffffffff810cddab>] ? local_clock+0x2b/0x40
> [   71.429923]  [<ffffffff810bbf20>] ? kthread_stop+0xf0/0xf0
> [   71.429927]  [<ffffffff8203842c>] ret_from_fork+0x7c/0xb0
> [   71.429931]  [<ffffffff810bbf20>] ? kthread_stop+0xf0/0xf0
> [   71.429933] ---[ end trace c511e3d74efea94e ]---
>
> looks like Greg forgot adding attr init.
>
> Can you fold attached patch into Greg's patch ?

Sure.  I don't know how to reproduce it, so I couldn't verify the fix,
but I added it to Greg's patch.  Thanks!

> Index: linux-2.6/drivers/pci/msi.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/msi.c
> +++ linux-2.6/drivers/pci/msi.c
> @@ -547,6 +547,7 @@ static int populate_msi_sysfs(struct pci
>                 msi_dev_attr = kzalloc(sizeof(*msi_dev_attr), GFP_KERNEL);
>                 if (!msi_dev_attr)
>                         return -ENOMEM;
> +               sysfs_attr_init(&msi_dev_attr->attr);
>                 sprintf(name, "%d", entry->irq);
>                 msi_dev_attr->attr.name = name;
>                 msi_dev_attr->attr.mode = S_IRUGO;
--
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