phylib: fix device deletion order in mdiobus_unregister()

Message ID 1441114565-2340-1-git-send-email-msalter@redhat.com
State New
Headers show

Commit Message

Mark Salter Sept. 1, 2015, 1:36 p.m.
commit 8b63ec1837fa ("phylib: Make PHYs children of their MDIO bus, not
the bus' parent.") uncovered a problem in mdiobus_unregister() which
leads to this warning when I reboot an APM Mustang (arm64) platform:

  WARNING: CPU: 7 PID: 4239 at fs/sysfs/group.c:224 sysfs_remove_group+0xa0/0xa4()
  sysfs group fffffe0000e07a10 not found for kobject 'xgene-mii-eth0:03'
  ...
  CPU: 7 PID: 4239 Comm: reboot Tainted: G            E   4.2.0-0.18.el7.test15.aarch64 #1
  Hardware name: AppliedMicro Mustang/Mustang, BIOS 1.1.0 Aug 26 2015
  Call Trace:
  [<fffffe000009739c>] dump_backtrace+0x0/0x170
  [<fffffe000009752c>] show_stack+0x20/0x2c
  [<fffffe00007436f0>] dump_stack+0x78/0x9c
  [<fffffe00000c2cb4>] warn_slowpath_common+0xa0/0xd8
  [<fffffe00000c2d60>] warn_slowpath_fmt+0x74/0x88
  [<fffffe0000293d3c>] sysfs_remove_group+0x9c/0xa4
  [<fffffe00004a8bac>] dpm_sysfs_remove+0x5c/0x70
  [<fffffe000049b388>] device_del+0x44/0x208
  [<fffffe000049b578>] device_unregister+0x2c/0x7c
  [<fffffe000050dc68>] mdiobus_unregister+0x48/0x94
  [<fffffe000052afd0>] xgene_enet_mdio_remove+0x28/0x44
  [<fffffe000052d3f0>] xgene_enet_remove+0xd0/0xd8
  [<fffffe000052d424>] xgene_enet_shutdown+0x2c/0x3c
  [<fffffe00004a204c>] platform_drv_shutdown+0x24/0x40
  [<fffffe000049d4f4>] device_shutdown+0xf0/0x1b4
  [<fffffe00000e31ec>] kernel_restart_prepare+0x40/0x4c
  [<fffffe00000e32f8>] kernel_restart+0x1c/0x80
  [<fffffe00000e3670>] SyS_reboot+0x17c/0x250

The problem is that mdiobus_unregister() deletes the bus device before
unregistering the phy devices on the bus. This wasn't a problem before
because the phys were not children of the bus:

  /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0:03
  /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0

But now that they are:

  /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0/xgene-mii-eth0:03

when mdiobus_unregister deletes the bus device, the phy subdirs are
removed from sysfs also. So when the phys are unregistered afterward,
we get the warning. This patch changes the order so that phys are
unregistered before the bus device is deleted.

Signed-off-by: Mark Salter <msalter@redhat.com>
---
 drivers/net/phy/mdio_bus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Florian Fainelli Sept. 1, 2015, 1:55 p.m. | #1
Le 09/01/15 06:36, Mark Salter a écrit :
> commit 8b63ec1837fa ("phylib: Make PHYs children of their MDIO bus, not
> the bus' parent.") uncovered a problem in mdiobus_unregister() which
> leads to this warning when I reboot an APM Mustang (arm64) platform:
> 
>   WARNING: CPU: 7 PID: 4239 at fs/sysfs/group.c:224 sysfs_remove_group+0xa0/0xa4()
>   sysfs group fffffe0000e07a10 not found for kobject 'xgene-mii-eth0:03'
>   ...
>   CPU: 7 PID: 4239 Comm: reboot Tainted: G            E   4.2.0-0.18.el7.test15.aarch64 #1
>   Hardware name: AppliedMicro Mustang/Mustang, BIOS 1.1.0 Aug 26 2015
>   Call Trace:
>   [<fffffe000009739c>] dump_backtrace+0x0/0x170
>   [<fffffe000009752c>] show_stack+0x20/0x2c
>   [<fffffe00007436f0>] dump_stack+0x78/0x9c
>   [<fffffe00000c2cb4>] warn_slowpath_common+0xa0/0xd8
>   [<fffffe00000c2d60>] warn_slowpath_fmt+0x74/0x88
>   [<fffffe0000293d3c>] sysfs_remove_group+0x9c/0xa4
>   [<fffffe00004a8bac>] dpm_sysfs_remove+0x5c/0x70
>   [<fffffe000049b388>] device_del+0x44/0x208
>   [<fffffe000049b578>] device_unregister+0x2c/0x7c
>   [<fffffe000050dc68>] mdiobus_unregister+0x48/0x94
>   [<fffffe000052afd0>] xgene_enet_mdio_remove+0x28/0x44
>   [<fffffe000052d3f0>] xgene_enet_remove+0xd0/0xd8
>   [<fffffe000052d424>] xgene_enet_shutdown+0x2c/0x3c
>   [<fffffe00004a204c>] platform_drv_shutdown+0x24/0x40
>   [<fffffe000049d4f4>] device_shutdown+0xf0/0x1b4
>   [<fffffe00000e31ec>] kernel_restart_prepare+0x40/0x4c
>   [<fffffe00000e32f8>] kernel_restart+0x1c/0x80
>   [<fffffe00000e3670>] SyS_reboot+0x17c/0x250
> 
> The problem is that mdiobus_unregister() deletes the bus device before
> unregistering the phy devices on the bus. This wasn't a problem before
> because the phys were not children of the bus:
> 
>   /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0:03
>   /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0
> 
> But now that they are:
> 
>   /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0/xgene-mii-eth0:03
> 
> when mdiobus_unregister deletes the bus device, the phy subdirs are
> removed from sysfs also. So when the phys are unregistered afterward,
> we get the warning. This patch changes the order so that phys are
> unregistered before the bus device is deleted.
> 
> Signed-off-by: Mark Salter <msalter@redhat.com>

Fixes: 8b63ec1837fa ("phylib: Make PHYs children of their MDIO bus, not
the bus' parent.")
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

Thanks!
Mark Langsdorf Sept. 1, 2015, 2:07 p.m. | #2
On 09/01/2015 08:36 AM, Mark Salter wrote:
> commit 8b63ec1837fa ("phylib: Make PHYs children of their MDIO bus, not
> the bus' parent.") uncovered a problem in mdiobus_unregister() which
> leads to this warning when I reboot an APM Mustang (arm64) platform:
>
>    WARNING: CPU: 7 PID: 4239 at fs/sysfs/group.c:224 sysfs_remove_group+0xa0/0xa4()
>    sysfs group fffffe0000e07a10 not found for kobject 'xgene-mii-eth0:03'
>    ...
>    CPU: 7 PID: 4239 Comm: reboot Tainted: G            E   4.2.0-0.18.el7.test15.aarch64 #1
>    Hardware name: AppliedMicro Mustang/Mustang, BIOS 1.1.0 Aug 26 2015
>    Call Trace:
>    [<fffffe000009739c>] dump_backtrace+0x0/0x170
>    [<fffffe000009752c>] show_stack+0x20/0x2c
>    [<fffffe00007436f0>] dump_stack+0x78/0x9c
>    [<fffffe00000c2cb4>] warn_slowpath_common+0xa0/0xd8
>    [<fffffe00000c2d60>] warn_slowpath_fmt+0x74/0x88
>    [<fffffe0000293d3c>] sysfs_remove_group+0x9c/0xa4
>    [<fffffe00004a8bac>] dpm_sysfs_remove+0x5c/0x70
>    [<fffffe000049b388>] device_del+0x44/0x208
>    [<fffffe000049b578>] device_unregister+0x2c/0x7c
>    [<fffffe000050dc68>] mdiobus_unregister+0x48/0x94
>    [<fffffe000052afd0>] xgene_enet_mdio_remove+0x28/0x44
>    [<fffffe000052d3f0>] xgene_enet_remove+0xd0/0xd8
>    [<fffffe000052d424>] xgene_enet_shutdown+0x2c/0x3c
>    [<fffffe00004a204c>] platform_drv_shutdown+0x24/0x40
>    [<fffffe000049d4f4>] device_shutdown+0xf0/0x1b4
>    [<fffffe00000e31ec>] kernel_restart_prepare+0x40/0x4c
>    [<fffffe00000e32f8>] kernel_restart+0x1c/0x80
>    [<fffffe00000e3670>] SyS_reboot+0x17c/0x250
>
> The problem is that mdiobus_unregister() deletes the bus device before
> unregistering the phy devices on the bus. This wasn't a problem before
> because the phys were not children of the bus:
>
>    /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0:03
>    /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0
>
> But now that they are:
>
>    /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0/xgene-mii-eth0:03
>
> when mdiobus_unregister deletes the bus device, the phy subdirs are
> removed from sysfs also. So when the phys are unregistered afterward,
> we get the warning. This patch changes the order so that phys are
> unregistered before the bus device is deleted.
>
> Signed-off-by: Mark Salter <msalter@redhat.com>
> ---

Tested-by: Mark Langsdorf <mlangsdo@redhat.com>

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David Miller Sept. 1, 2015, 10:03 p.m. | #3
From: Mark Salter <msalter@redhat.com>
Date: Tue,  1 Sep 2015 09:36:05 -0400

> commit 8b63ec1837fa ("phylib: Make PHYs children of their MDIO bus, not
> the bus' parent.") uncovered a problem in mdiobus_unregister() which
> leads to this warning when I reboot an APM Mustang (arm64) platform:
 ...
> The problem is that mdiobus_unregister() deletes the bus device before
> unregistering the phy devices on the bus. This wasn't a problem before
> because the phys were not children of the bus:
> 
>   /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0:03
>   /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0
> 
> But now that they are:
> 
>   /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0/xgene-mii-eth0:03
> 
> when mdiobus_unregister deletes the bus device, the phy subdirs are
> removed from sysfs also. So when the phys are unregistered afterward,
> we get the warning. This patch changes the order so that phys are
> unregistered before the bus device is deleted.
> 
> Signed-off-by: Mark Salter <msalter@redhat.com>

Applied and queued up for -stable, thanks.
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Patch

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 46a14cb..02a4615 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -303,12 +303,12 @@  void mdiobus_unregister(struct mii_bus *bus)
 	BUG_ON(bus->state != MDIOBUS_REGISTERED);
 	bus->state = MDIOBUS_UNREGISTERED;
 
-	device_del(&bus->dev);
 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		if (bus->phy_map[i])
 			device_unregister(&bus->phy_map[i]->dev);
 		bus->phy_map[i] = NULL;
 	}
+	device_del(&bus->dev);
 }
 EXPORT_SYMBOL(mdiobus_unregister);