Patch "phylib: fix device deletion order in mdiobus_unregister()" has been added to the 4.2-stable tree

Patch "phylib: fix device deletion order in mdiobus_unregister()" has been added to the 4.2-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    phylib: fix device deletion order in mdiobus_unregister()

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     phylib-fix-device-deletion-order-in-mdiobus_unregister.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed Sep 30 05:25:07 CEST 2015
From: Mark Salter <msalter@redhat.com>
Date: Tue, 1 Sep 2015 09:36:05 -0400
Subject: phylib: fix device deletion order in mdiobus_unregister()

From: Mark Salter <msalter@redhat.com>

[ Upstream commit b6c6aedcbcbacd7b0cb4b64ed5ac835bc1c60a03 ]

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.

Fixes: 8b63ec1837fa ("phylib: Make PHYs children of their MDIO bus, not the bus' parent.")
Signed-off-by: Mark Salter <msalter@redhat.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/phy/mdio_bus.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -303,12 +303,12 @@ void mdiobus_unregister(struct mii_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);
 


Patches currently in stable-queue which might be from msalter@redhat.com are

queue-4.2/phylib-fix-device-deletion-order-in-mdiobus_unregister.patch