Re: [PATCH net-next 10/10] net: dsa: Add lockdep class to tx queues to avoid lockdep splat
From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2015-05-05 23:22:49
On 05/05/15 16:09, Andrew Lunn wrote:
DSA stacks an Ethernet device on top of an Ethernet device. This can
cause false positive lockdep splats for the transmit queue:
=============================================
[ INFO: possible recursive locking detected ]
4.0.0-rc7-01838-g70621a215fc7 #386 Not tainted
---------------------------------------------
kworker/0:0/4 is trying to acquire lock:
(_xmit_ETHER#2){+.-...}, at: [<c040e95c>] sch_direct_xmit+0xa8/0x1fc
but task is already holding lock:
(_xmit_ETHER#2){+.-...}, at: [<c03f4208>] __dev_queue_xmit+0x4d4/0x56c
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(_xmit_ETHER#2);
lock(_xmit_ETHER#2);
To avoid this, walk the tq queues of the dsa slaves and set a lockdep
class.Had meant to fix that a while ago when this was bugging me, thanks for doing this!
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Florian Fainelli <f.fainelli@gmail.com> -- Florian