dsa: Fix conversion from host device to mii bus
authorGuenter Roeck <linux@roeck-us.net>
Fri, 17 Oct 2014 19:30:58 +0000 (12:30 -0700)
committerDavid S. Miller <davem@davemloft.net>
Sat, 18 Oct 2014 03:52:08 +0000 (23:52 -0400)
commitb184e497f7fe2895b2175859e0cb21ae5d531555
treeea1d277d73e4388820caf1fab98f8d6f53f993dc
parent643566d4b47e2956110e79c0e6f65db9b9ea42c6
dsa: Fix conversion from host device to mii bus

Commit b4d2394d01bc ("dsa: Replace mii_bus with a generic host device")
replaces mii_bus with a generic host_dev, and introduces
dsa_host_dev_to_mii_bus() to support conversion from host_dev to mii_bus.
However, in some cases it uses to_mii_bus to perform that conversion.
Since host_dev is not the phy bus device but typically a platform device,
this fails and results in a crash with the affected drivers.

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff81781d35>] __mutex_lock_slowpath+0x75/0x100
PGD 406783067 PUD 406784067 PMD 0
Oops: 0002 [#1] SMP
...
Call Trace:
[<ffffffff810a538b>] ? pick_next_task_fair+0x61b/0x880
[<ffffffff81781de3>] mutex_lock+0x23/0x37
[<ffffffff81533244>] mdiobus_read+0x34/0x60
[<ffffffff8153b95a>] __mv88e6xxx_reg_read+0x8a/0xa0
[<ffffffff8153b9bc>] mv88e6xxx_reg_read+0x4c/0xa0

Fixes: b4d2394d01bc ("dsa: Replace mii_bus with a generic host device")
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/dsa/mv88e6060.c
drivers/net/dsa/mv88e6xxx.c