diff mbox

[v4,5/6] pci: Use parent domain number when allocating child busses.

Message ID CACoXjcnP80rSaYqy2EK8SBh8Q=5E8kh_GQ84Y_0hg3WrQ=fy+A@mail.gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Tanmay Inamdar March 3, 2014, 11:14 p.m. UTC 
Hello Liviu,

Thanks for fixing up domain_nr. Now I have moved on further to a new
domain_nr related warning dump :-)

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
xgene-pcie 1f500000.pcie: (rc) x8 gen-3 link up
pci_bus 0001:00: scanning bus
pci_setup_device:1101 domain_nr = 1
pci 0001:00:00.0: [e008:e004] type 01 class 0x060400
pci 0001:00:00.0: reg 0x10: [mem 0x4000000000-0x7fffffffff 64bit]
pci 0001:00:00.0: calling xgene_pcie_fixup_bridge+0x0/0x80
pci 0001:00:00.0: Hiding X-Gene pci host bridge resources 0001:00:00.0
pci 0001:00:00.0: supports D1 D2
pci_bus 0001:00: fixups for bus
pci 0001:00:00.0: scanning [bus 03-03] behind bridge, pass 0
pci 0001:00:00.0: bridge configuration invalid ([bus 03-03]), reconfiguring
pci 0001:00:00.0: scanning [bus 00-00] behind bridge, pass 1
** pci_scan_bridge:855  pci_domain_nr(bus) = 1
** pci_alloc_child_bus:681  pci_domain_nr(bus) = 1
pci_bus 0001:01: scanning bus
pci_setup_device:1101 domain_nr = 0
pci 0000:01:00.0: [15b3:1003] type 00 class 0x020000
pci 0000:01:00.0: reg 0x10: [mem 0x00100000-0x001fffff 64bit]
pci 0000:01:00.0: reg 0x18: [mem 0x00800000-0x00ffffff 64bit pref]
pci 0000:01:00.0: reg 0x30: [mem 0x01000000-0x010fffff pref]
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at
/home/tinamdar/work/open-source/linux/fs/sysfs/dir.c:52
sysfs_warn_dup+0x80/0xc0()
sysfs: cannot create duplicate filename '/bus/pci/devices/0000:01:00.0'
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc5+ #40
Call trace:
[<ffffffc000088180>] dump_backtrace+0x0/0x140
[<ffffffc0000882d0>] show_stack+0x10/0x20
[<ffffffc0004f65ac>] dump_stack+0x74/0xc4
[<ffffffc000096e04>] warn_slowpath_common+0x84/0xc0
[<ffffffc000096e8c>] warn_slowpath_fmt+0x4c/0x60
[<ffffffc0001b83dc>] sysfs_warn_dup+0x7c/0xc0
[<ffffffc0001b8894>] sysfs_do_create_link_sd.isra.2+0xf4/0x100
[<ffffffc0001b88bc>] sysfs_create_link+0x1c/0x40
[<ffffffc0003250b0>] bus_add_device+0x110/0x1c0
[<ffffffc000322f1c>] device_add+0x31c/0x520
[<ffffffc0002c444c>] pci_device_add+0xec/0x140
[<ffffffc0004f1758>] pci_scan_single_device+0x98/0xe0
[<ffffffc0002c44e8>] pci_scan_slot+0x48/0x120
[<ffffffc0002c5368>] pci_scan_child_bus+0x48/0x140
[<ffffffc0002c522c>] pci_scan_bridge+0x4ec/0x5e0
[<ffffffc0002c53c8>] pci_scan_child_bus+0xa8/0x140
[<ffffffc0004f1b30>] pci_rescan_bus+0x10/0x40
[<ffffffc0006a12ac>] xgene_pcie_probe_bridge+0x660/0x72c
[<ffffffc000327d20>] platform_drv_probe+0x20/0x60
[<ffffffc000325e30>] really_probe+0xf0/0x220
[<ffffffc000326080>] __driver_attach+0xa0/0xc0
[<ffffffc000323ed4>] bus_for_each_dev+0x54/0xa0
[<ffffffc0003258bc>] driver_attach+0x1c/0x40
[<ffffffc00032548c>] bus_add_driver+0x14c/0x220
[<ffffffc00032683c>] driver_register+0x5c/0x120
[<ffffffc000327cdc>] __platform_driver_register+0x5c/0x80
[<ffffffc0006a0c40>] xgene_pcie_driver_init+0x14/0x20
[<ffffffc0000814c0>] do_one_initcall+0xe0/0x160
[<ffffffc00068c934>] kernel_init_freeable+0x134/0x1d8
[<ffffffc0004f07ac>] kernel_init+0xc/0xe0
---[ end trace 3ee052d463aab7f3 ]---
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at
/home/tinamdar/work/open-source/linux/drivers/pci/probe.c:1380
pci_device_add+0x128/0x140()
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I have made a small fix above your patch. After the fix is applied,
dumps are gone and the enumeration finishes up smoothly for all the
ports.
Since the change is small, just pasting it here. Please review and
apply if it's clean.

        pci_set_bus_speed(child);

Thanks,
Tanmay

On Mon, Mar 3, 2014 at 9:33 AM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> pci_alloc_child_bus() uses the newly allocated child bus to figure
> out the domain number that is going to use for setting the device
> name. A better option is to use the parent bus domain number.
>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 26237a0..a12cda5 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -677,7 +677,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
>          * now as the parent is not properly set up yet.
>          */
>         child->dev.class = &pcibus_class;
> -       dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);
> +       dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(parent), busnr);
>
>         /*
>          * Set up the primary, secondary and subordinate
> --
> 1.9.0
>

Comments

Liviu Dudau March 3, 2014, 11:51 p.m. UTC | #1 
On Mon, Mar 03, 2014 at 03:14:47PM -0800, Tanmay Inamdar wrote:
> Hello Liviu,
> 
> Thanks for fixing up domain_nr. Now I have moved on further to a new
> domain_nr related warning dump :-)
> 
> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> xgene-pcie 1f500000.pcie: (rc) x8 gen-3 link up
> pci_bus 0001:00: scanning bus
> pci_setup_device:1101 domain_nr = 1
> pci 0001:00:00.0: [e008:e004] type 01 class 0x060400
> pci 0001:00:00.0: reg 0x10: [mem 0x4000000000-0x7fffffffff 64bit]
> pci 0001:00:00.0: calling xgene_pcie_fixup_bridge+0x0/0x80
> pci 0001:00:00.0: Hiding X-Gene pci host bridge resources 0001:00:00.0
> pci 0001:00:00.0: supports D1 D2
> pci_bus 0001:00: fixups for bus
> pci 0001:00:00.0: scanning [bus 03-03] behind bridge, pass 0
> pci 0001:00:00.0: bridge configuration invalid ([bus 03-03]), reconfiguring
> pci 0001:00:00.0: scanning [bus 00-00] behind bridge, pass 1
> ** pci_scan_bridge:855  pci_domain_nr(bus) = 1
> ** pci_alloc_child_bus:681  pci_domain_nr(bus) = 1
> pci_bus 0001:01: scanning bus
> pci_setup_device:1101 domain_nr = 0

Why does the domain_nr change here?

> pci 0000:01:00.0: [15b3:1003] type 00 class 0x020000
> pci 0000:01:00.0: reg 0x10: [mem 0x00100000-0x001fffff 64bit]
> pci 0000:01:00.0: reg 0x18: [mem 0x00800000-0x00ffffff 64bit pref]
> pci 0000:01:00.0: reg 0x30: [mem 0x01000000-0x010fffff pref]
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at
> /home/tinamdar/work/open-source/linux/fs/sysfs/dir.c:52
> sysfs_warn_dup+0x80/0xc0()
> sysfs: cannot create duplicate filename '/bus/pci/devices/0000:01:00.0'
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc5+ #40
> Call trace:
> [<ffffffc000088180>] dump_backtrace+0x0/0x140
> [<ffffffc0000882d0>] show_stack+0x10/0x20
> [<ffffffc0004f65ac>] dump_stack+0x74/0xc4
> [<ffffffc000096e04>] warn_slowpath_common+0x84/0xc0
> [<ffffffc000096e8c>] warn_slowpath_fmt+0x4c/0x60
> [<ffffffc0001b83dc>] sysfs_warn_dup+0x7c/0xc0
> [<ffffffc0001b8894>] sysfs_do_create_link_sd.isra.2+0xf4/0x100
> [<ffffffc0001b88bc>] sysfs_create_link+0x1c/0x40
> [<ffffffc0003250b0>] bus_add_device+0x110/0x1c0
> [<ffffffc000322f1c>] device_add+0x31c/0x520
> [<ffffffc0002c444c>] pci_device_add+0xec/0x140
> [<ffffffc0004f1758>] pci_scan_single_device+0x98/0xe0
> [<ffffffc0002c44e8>] pci_scan_slot+0x48/0x120
> [<ffffffc0002c5368>] pci_scan_child_bus+0x48/0x140
> [<ffffffc0002c522c>] pci_scan_bridge+0x4ec/0x5e0
> [<ffffffc0002c53c8>] pci_scan_child_bus+0xa8/0x140
> [<ffffffc0004f1b30>] pci_rescan_bus+0x10/0x40
> [<ffffffc0006a12ac>] xgene_pcie_probe_bridge+0x660/0x72c
> [<ffffffc000327d20>] platform_drv_probe+0x20/0x60
> [<ffffffc000325e30>] really_probe+0xf0/0x220
> [<ffffffc000326080>] __driver_attach+0xa0/0xc0
> [<ffffffc000323ed4>] bus_for_each_dev+0x54/0xa0
> [<ffffffc0003258bc>] driver_attach+0x1c/0x40
> [<ffffffc00032548c>] bus_add_driver+0x14c/0x220
> [<ffffffc00032683c>] driver_register+0x5c/0x120
> [<ffffffc000327cdc>] __platform_driver_register+0x5c/0x80
> [<ffffffc0006a0c40>] xgene_pcie_driver_init+0x14/0x20
> [<ffffffc0000814c0>] do_one_initcall+0xe0/0x160
> [<ffffffc00068c934>] kernel_init_freeable+0x134/0x1d8
> [<ffffffc0004f07ac>] kernel_init+0xc/0xe0
> ---[ end trace 3ee052d463aab7f3 ]---
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at
> /home/tinamdar/work/open-source/linux/drivers/pci/probe.c:1380
> pci_device_add+0x128/0x140()
> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> 
> I have made a small fix above your patch. After the fix is applied,
> dumps are gone and the enumeration finishes up smoothly for all the
> ports.
> Since the change is small, just pasting it here. Please review and
> apply if it's clean.

Honestly, I have no idea. I kept staring at the code for a better part of an hour
trying to decipher what the intent of the code was, without too much progress. I
still don't understand why the code in pci_alloc_child_bus() takes a shortcut when
the bridge argument is NULL when in my opinion it should use parent->bridge instead
and continue as normal.

> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index a12cda5..aac8366 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -693,7 +693,7 @@ static struct pci_bus *pci_alloc_child_bus(struct
> pci_bus *parent,
>         }
> 
>         child->self = bridge;
> -       child->bridge = get_device(&bridge->dev);
> +       child->bridge = get_device(parent->bridge);
>         child->dev.parent = child->bridge;

Hmm, not sure why this is needed. What does get_device(&bridge->dev)
return for you? The next line sets child->dev.parent to child->bridge,
but with your change I'm not sure we end up using the correct parent.

Can you try to revert your change and modify the implementation of pci_domain_nr() in arm64
to look like this:

static inline int pci_domain_nr(struct pci_bus *bus)
{
	struct pci_host_bridge *bridge;

	while (bus->parent)
		bus = bus->parent;

	bridge = to_pci_host_bridge(bus->bridge);
	if (bridge)
		return bridge->domain_nr;

	return 0;
}

Please let me know what results you get.

Best regards,
Liviu


>         pci_set_bus_of_node(child);
>         pci_set_bus_speed(child);
> 
> Thanks,
> Tanmay
> 
> On Mon, Mar 3, 2014 at 9:33 AM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> > pci_alloc_child_bus() uses the newly allocated child bus to figure
> > out the domain number that is going to use for setting the device
> > name. A better option is to use the parent bus domain number.
> >
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> >
> > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > index 26237a0..a12cda5 100644
> > --- a/drivers/pci/probe.c
> > +++ b/drivers/pci/probe.c
> > @@ -677,7 +677,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
> >          * now as the parent is not properly set up yet.
> >          */
> >         child->dev.class = &pcibus_class;
> > -       dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);
> > +       dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(parent), busnr);
> >
> >         /*
> >          * Set up the primary, secondary and subordinate
> > --
> > 1.9.0
> >
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
diff mbox

Patch

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index a12cda5..aac8366 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -693,7 +693,7 @@  static struct pci_bus *pci_alloc_child_bus(struct
pci_bus *parent,
        }

        child->self = bridge;
-       child->bridge = get_device(&bridge->dev);
+       child->bridge = get_device(parent->bridge);
        child->dev.parent = child->bridge;
        pci_set_bus_of_node(child);