Re: alpha runtime warnings due to commit 0e4c2eeb758 ("alpha/PCI: Replace pci_fixup_irqs() call with host ...")

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

Bjorn, Guenter,

On Wed, Sep 20, 2017 at 12:31:04PM +0100, Lorenzo Pieralisi wrote:
> On Tue, Sep 19, 2017 at 11:02:33AM -0700, Guenter Roeck wrote:
> > On Tue, Sep 19, 2017 at 10:12:32AM +0100, Lorenzo Pieralisi wrote:
> > > On Mon, Sep 18, 2017 at 07:00:55PM -0700, Guenter Roeck wrote:
> > > > Hi,
> > > > 
> > > > I see the following runtime warnings in mainline when running alpha images in qemu.
> > > > 
> > > > 
> > > > Floppy drive(s): fd0 is 2.88M
> > > > ide0: disabled, no IRQ
> > > > ide0: failed to initialize IDE interface
> > > > ide0: disabling port
> > > > cmd64x 0000:00:02.0: IDE controller (0x1095:0x0646 rev 0x07)
> > > > CMD64x_IDE 0000:00:02.0: BAR 0: can't reserve [io  0x8050-0x8057]
> > > > cmd64x 0000:00:02.0: can't reserve resources
> > > > CMD64x_IDE: probe of 0000:00:02.0 failed with error -16
> > > > ide_generic: please use "probe_mask=0x3f" module parameter for probing all legacy ISA IDE ports
> > > > ------------[ cut here ]------------
> > > > WARNING: CPU: 0 PID: 1 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x94/0xd0
> > > > sysfs: cannot create duplicate filename '/class/ide_port/ide0'
> > > > ...
> > > > 
> > > > Trace:
> > > > [<fffffc00003308a0>] __warn+0x160/0x190
> > > > [<fffffc000048c9f4>] sysfs_warn_dup+0x94/0xd0
> > > > [<fffffc0000330928>] warn_slowpath_fmt+0x58/0x70
> > > > [<fffffc000048c9f4>] sysfs_warn_dup+0x94/0xd0
> > > > [<fffffc0000486d40>] kernfs_path_from_node+0x30/0x60
> > > > [<fffffc00004874ac>] kernfs_put+0x16c/0x2c0
> > > > [<fffffc00004874ac>] kernfs_put+0x16c/0x2c0
> > > > [<fffffc000048d010>] sysfs_do_create_link_sd.isra.2+0x100/0x120
> > > > [<fffffc00005b9d64>] device_add+0x2a4/0x7c0
> > > > [<fffffc00005ba5cc>] device_create_groups_vargs+0x14c/0x170
> > > > [<fffffc00005ba518>] device_create_groups_vargs+0x98/0x170
> > > > [<fffffc00005ba690>] device_create+0x50/0x70
> > > > [<fffffc00005df36c>] ide_host_register+0x48c/0xa00
> > > > [<fffffc00005df330>] ide_host_register+0x450/0xa00
> > > > [<fffffc00005ba2a0>] device_register+0x20/0x50
> > > > [<fffffc00005df330>] ide_host_register+0x450/0xa00
> > > > [<fffffc00005df944>] ide_host_add+0x64/0xe0
> > > > [<fffffc000079b41c>] kobject_uevent_env+0x16c/0x710
> > > > [<fffffc0000310288>] do_one_initcall+0x68/0x260
> > > > [<fffffc00007b13bc>] kernel_init+0x1c/0x1a0
> > > > [<fffffc00007b13a0>] kernel_init+0x0/0x1a0
> > > > [<fffffc0000311868>] ret_from_kernel_thread+0x18/0x20
> > > > [<fffffc00007b13a0>] kernel_init+0x0/0x1a0
> > > > 
> > > > ---[ end trace 24a70433c3e4d374 ]---
> > > > ide0: disabling port
> > > > 
> > > > [ multiple times ]
> > > > 
> > > > A complete log is available at http://kerneltests.org/builders/qemu-alpha-master.
> > > > 
> > > > Prior to the offending commit, the kernel log looks as follows.
> > > > 
> > > > ...
> > > > Uniform Multi-Platform E-IDE driver
> > > > cmd64x 0000:00:02.0: IDE controller (0x1095:0x0646 rev 0x07)
> > > > cmd64x 0000:00:02.0: IDE port disabled
> > > > cmd64x 0000:00:02.0: 100% native mode on irq 28
> > > > PCI: Setting latency timer of device 0000:00:02.0 to 64
> > > >     ide0: BM-DMA at 0x8040-0x8047
> > > > Floppy drive(s): fd0 is 2.88M
> > > > ide0 at 0x8050-0x8057,0x8062 on irq 28 (serialized)
> > > > ide_generic: please use "probe_mask=0x3f" module parameter for probing all legacy ISA IDE ports
> > > > ide1 at 0x1f0-0x1f7,0x3f6 on irq 14
> > > > ide2 at 0x170-0x177,0x376 on irq 15
> > > > ide-gd driver 1.18
> > > > ide-cd driver 5.00
> > > > ...
> > > > 
> > > > Reverting the commit is not possible due to context changes.
> > > > 
> > > > Bisect log is attached.
> > > 
> > > Ok thanks. Can you please check if the diff below fixes the issue ?
> > > 
> > It does. Feel free to add
> > 
> > Tested-by: Guenter Roeck <linux@roeck-us.net>
> > 
> > to the actual patch.
> > 
> > > I think the problem is that now we allocate the IRQ at device_probe
> > > instead of device_add time, if the patch below fixes the issue the
> > > question is whether we want to move pci_assign_irq() to pci_device_add()
> > > for ALL PCI devices or just fix this for IDE subsytem.
> > > 
> > 
> > That I can not answer ...
> 
> It is not a clean-cut answer. Moving pci_assign_irq() from
> 
> pci_device_probe()
> 
> to
> 
> pci_device_add()
> 
> would fix this issue too and just map/swizzle() irqs for ALL PCI devices
> earlier (even ones that are not even probed); it should have no side
> effects (famous last words) and would be a cleaner fix.
> 
> Fix below is fine but I am not a big fan of it, I would like to
> get Bjorn's opinion before I send a fix out.

I think that for now the fix below should be ok, I would like to
send it out before -rc3, the only question is related to the
"Fixes:" tag, I am reluctant to add:

Fixes: 0e4c2eeb758 ("alpha/PCI: Replace pci_fixup_irqs() call with host bridge mapping hooks")

since this is not necessarily just an alpha/PCI bug (ie it is related to
IDE legacy IRQ routing - which Guenter hit on Alpha), the tag can be
misleading in that sense.

Please let me know what you think, I will send out the patch then.

Thanks,
Lorenzo

> Thanks,
> Lorenzo
> 
> > Guenter
> > 
> > > Lorenzo
> > > 
> > > -- >8 --
> > > diff --git a/drivers/ide/setup-pci.c b/drivers/ide/setup-pci.c
> > > index 112d2fe..94ca9cc 100644
> > > --- a/drivers/ide/setup-pci.c
> > > +++ b/drivers/ide/setup-pci.c
> > > @@ -502,6 +502,8 @@ static int do_ide_setup_pci_device(struct pci_dev *dev,
> > >  {
> > >  	int pciirq, ret;
> > >  
> > > +	pci_assign_irq(dev);
> > > +
> > >  	/*
> > >  	 * Can we trust the reported IRQ?
> > >  	 */