Andy Gospodarek [off-list ref] wrote:

The main purpose of this patch is to clean-up the bonding code so that
several important operations are not done in the incorrect (softirq)
context. Whenever a kernel is compiled with CONFIG_DEBUG_SPINLOCK_SLEEP
all sorts of backtraces are spewed to the log since might_sleep will
kindly remind us we are doing something in a atomic context when we
probably should not.

[...]

	I'll look at the patch in detail in a bit (and I have 802.3ad
switches to test on), but on first glance, does this not still hold a
lock during failover operations in balance-alb mode?  I.e., this doesn't
change the locking model, it just moves the timers to workqueues and
relaxes the _bh locking.

	The really problematic case calls dev_set_mac_address() with a
lock held, and I don't see that this patch changes that behavior.  Do
you still get the lock warnings during link fail / recovery in
balance-alb mode?

	Also, on an CONFIG_PREEMPT kernel, it'll still get the sleep
warnings, since in_atomic() will trip __might_sleep() for any lock (if
I'm reading things correctly).

	Don't get me wrong, this (switching to workqueues, etc) needs to
be done, but I don't think this patch really resolves the underlying
problem that causes the warnings.

	Let me see if I can dust off the extensive patch that does
change the locking model; I'll see if I can bring it up to the current
git and post it.

	-J

---
	-Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com