linux-kernel - [PATCH 4.2 01/30] phylib: fix device deletion order in mdiobus

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu,  1 Oct 2015 11:21:23 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Mark Salter <msalter@...hat.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Mark Langsdorf <mlangsdo@...hat.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.2 01/30] phylib: fix device deletion order in mdiobus_unregister()

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Salter <msalter@...hat.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@...hat.com>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Tested-by: Mark Langsdorf <mlangsdo@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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);
 


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/