Re: [PATCH RT] blk-mq: revert raw locks, post pone notifier to POST_DEAD

[Mike Galbraith <umgwanakikbuti@gmail.com>]

On Wed, 2014-05-07 at 10:19 +0200, Sebastian Andrzej Siewior wrote: 
> On 05/03/2014 07:03 PM, Mike Galbraith wrote:
> >> Mike, I see that lockdep splat (sleeping while atomic) during cpu-hotplug.
> >> Don't you see this, too?
> > 
> > Nope, didn't.
> 
> Hmm. blk_mq_hctx_notify(). It does
> 	spin_lock(&ctx->lock);
> 
> Isn't this a sleeping spinlock for you or don't get here at all?

Hm, cts->lock...

git@marge:~/suse/scratch_area/linux-3.12-SLE12-RT> grep -IR cpu_lock block
git@marge:~/suse/scratch_area/linux-3.12-SLE12-RT>

(here lock lock lock, here boy)

marge:/usr/local/src/kernel/linux-3.x.git # grep -IR cpu_lock block
marge:/usr/local/src/kernel/linux-3.x.git # 

marge:/usr/local/src/kernel/linux-3.14 # grep -IR cpu_lock block
marge:/usr/local/src/kernel/linux-3.14 #

(what the..)

marge:/usr/local/src/kernel/linux-3.14-rt # grep -IR cpu_lock block
block/blk-mq.c: spin_lock(&ctx->cpu_lock);
block/blk-mq.c: spin_unlock(&ctx->cpu_lock);
block/blk-mq.c:                         spin_unlock(&ctx->cpu_lock);
block/blk-mq.c:                         spin_lock(&ctx->cpu_lock);
block/blk-mq.c:         spin_lock_init(&__ctx->cpu_lock);
block/blk-mq.h: spinlock_t              cpu_lock;
marge:/usr/local/src/kernel/linux-3.14-rt #

(aha!)

Nope, I definitely don't get there.

	-Mike