[PATCH] nvme: add missing lock nesting notation

[Johannes Thumshirn]

On 2016-04-05 08:42, Ming Lin wrote:
> From: Ming Lin <ming.l at ssi.samsung.com>
> 
> When unloading driver, nvme_disable_io_queues() calls 
> nvme_delete_queue()
> that sends nvme_admin_delete_cq command to admin sq. So when the 
> command
> completed, the lock acquired by nvme_irq() actually belongs to admin 
> queue.
> 
> While the lock that nvme_del_cq_end() trying to acquire belongs to io 
> queue.
> So it will not deadlock.
> 
> This patch adds lock nesting notation to fix following report.
> 
> [  109.840952] =============================================
> [  109.846379] [ INFO: possible recursive locking detected ]
> [  109.851806] 4.5.0+ #180 Tainted: G            E
> [  109.856533] ---------------------------------------------
> [  109.861958] swapper/0/0 is trying to acquire lock:
> [  109.866771]  (&(&nvmeq->q_lock)->rlock){-.....}, at:
> [<ffffffffc0820bc6>] nvme_del_cq_end+0x26/0x70 [nvme]
> [  109.876535]
> [  109.876535] but task is already holding lock:
> [  109.882398]  (&(&nvmeq->q_lock)->rlock){-.....}, at:
> [<ffffffffc0820c2b>] nvme_irq+0x1b/0x50 [nvme]
> [  109.891547]
> [  109.891547] other info that might help us debug this:
> [  109.898107]  Possible unsafe locking scenario:
> [  109.898107]
> [  109.904056]        CPU0
> [  109.906515]        ----
> [  109.908974]   lock(&(&nvmeq->q_lock)->rlock);
> [  109.913381]   lock(&(&nvmeq->q_lock)->rlock);
> [  109.917787]
> [  109.917787]  *** DEADLOCK ***
> [  109.917787]
> [  109.923738]  May be due to missing lock nesting notation
> [  109.923738]
> [  109.930558] 1 lock held by swapper/0/0:
> [  109.934413]  #0:  (&(&nvmeq->q_lock)->rlock){-.....}, at:
> [<ffffffffc0820c2b>] nvme_irq+0x1b/0x50 [nvme]
> [  109.944010]
> [  109.944010] stack backtrace:
> [  109.948389] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G            E
> 4.5.0+ #180
> [  109.955734] Hardware name: Dell Inc. OptiPlex 7010/0YXT71, BIOS A15
> 08/12/2013
> [  109.962989]  0000000000000000 ffff88011e203c38 ffffffff81383d9c
> ffffffff81c13540
> [  109.970478]  ffffffff826711d0 ffff88011e203ce8 ffffffff810bb429
> 0000000000000046
> [  109.977964]  0000000000000046 0000000000000000 0000000000b2e597
> ffffffff81f4cb00
> [  109.985453] Call Trace:
> [  109.987911]  <IRQ>  [<ffffffff81383d9c>] dump_stack+0x85/0xc9
> [  109.993711]  [<ffffffff810bb429>] __lock_acquire+0x19b9/0x1c60
> [  109.999575]  [<ffffffff810b6d1d>] ? trace_hardirqs_off+0xd/0x10
> [  110.005524]  [<ffffffff810b386d>] ? complete+0x3d/0x50
> [  110.010688]  [<ffffffff810bb760>] lock_acquire+0x90/0xf0
> [  110.016029]  [<ffffffffc0820bc6>] ? nvme_del_cq_end+0x26/0x70 [nvme]
> [  110.022418]  [<ffffffff81772afb>] _raw_spin_lock_irqsave+0x4b/0x60
> [  110.028632]  [<ffffffffc0820bc6>] ? nvme_del_cq_end+0x26/0x70 [nvme]
> [  110.035019]  [<ffffffffc0820bc6>] nvme_del_cq_end+0x26/0x70 [nvme]
> [  110.041232]  [<ffffffff8135b485>] blk_mq_end_request+0x35/0x60
> [  110.047095]  [<ffffffffc0821ad8>] nvme_complete_rq+0x68/0x190 [nvme]
> [  110.053481]  [<ffffffff8135b53f>] 
> __blk_mq_complete_request+0x8f/0x130
> [  110.060043]  [<ffffffff8135b611>] blk_mq_complete_request+0x31/0x40
> [  110.066343]  [<ffffffffc08209e3>] __nvme_process_cq+0x83/0x240 
> [nvme]
> [  110.072818]  [<ffffffffc0820c35>] nvme_irq+0x25/0x50 [nvme]
> [  110.078419]  [<ffffffff810cdb66>] handle_irq_event_percpu+0x36/0x110
> [  110.084804]  [<ffffffff810cdc77>] handle_irq_event+0x37/0x60
> [  110.090491]  [<ffffffff810d0ea3>] handle_edge_irq+0x93/0x150
> [  110.096180]  [<ffffffff81012306>] handle_irq+0xa6/0x130
> [  110.101431]  [<ffffffff81011abe>] do_IRQ+0x5e/0x120
> [  110.106333]  [<ffffffff8177384c>] common_interrupt+0x8c/0x8c
> 
> Signed-off-by: Ming Lin <ming.l at ssi.samsung.com>
> ---

Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>