[PATCH v2] nvme: Suspend all queues before deletion

[keith.busch@intel.com (Keith Busch)]

On Tue, Aug 02, 2016@11:10:38PM -0300, Gabriel Krisman Bertazi wrote:
> Yes, that approach seems to be ok. Please take the tested v2 below, in
> which I apply your suggestion, as well as clean up a bit the code in
> nvme_disable_io_queues and simplify the logic a bit.

The new patch looks good to me.


 
> -- >8 --
> Subject: [PATCH v2] nvme: Suspend all queues before deletion
> 
> When nvme_delete_queue fails in the first pass of the
> nvme_disable_io_queues() loop, we return early, failing to suspend all
> of the IO queues.  Later, on the nvme_pci_disable path, this causes us
> to disable MSI without actually having freed all the IRQs, which
> triggers the BUG_ON in free_msi_irqs(), as show below.
> 
> This patch refactors nvme_disable_io_queues to suspend all queues before
> start submitting delete queue commands.  This way, we ensure that we
> have at least returned every IRQ before continuing with the removal
> path.
> 
> [  487.529200] kernel BUG at ../drivers/pci/msi.c:368!
> cpu 0x46: Vector: 700 (Program Check) at [c0000078c5b83650]
>     pc: c000000000627a50: free_msi_irqs+0x90/0x200
>     lr: c000000000627a40: free_msi_irqs+0x80/0x200
>     sp: c0000078c5b838d0
>    msr: 9000000100029033
>   current = 0xc0000078c5b40000
>   paca    = 0xc000000002bd7600   softe: 0        irq_happened: 0x01
>     pid   = 1376, comm = kworker/70:1H
> kernel BUG at ../drivers/pci/msi.c:368!
> Linux version 4.7.0.mainline+ (root at iod76) (gcc version 5.3.1 20160413
> (Ubuntu/IBM 5.3.1-14ubuntu2.1) ) #104 SMP Fri Jul 29 09:20:17 CDT 2016
> enter ? for help
> [c0000078c5b83920] d0000000363b0cd8 nvme_dev_disable+0x208/0x4f0 [nvme]
> [c0000078c5b83a10] d0000000363b12a4 nvme_timeout+0xe4/0x250 [nvme]
> [c0000078c5b83ad0] c0000000005690e4 blk_mq_rq_timed_out+0x64/0x110
> [c0000078c5b83b40] c00000000056c930 bt_for_each+0x160/0x170
> [c0000078c5b83bb0] c00000000056d928 blk_mq_queue_tag_busy_iter+0x78/0x110
> [c0000078c5b83c00] c0000000005675d8 blk_mq_timeout_work+0xd8/0x1b0
> [c0000078c5b83c50] c0000000000e8cf0 process_one_work+0x1e0/0x590
> [c0000078c5b83ce0] c0000000000e9148 worker_thread+0xa8/0x660
> [c0000078c5b83d80] c0000000000f2090 kthread+0x110/0x130
> [c0000078c5b83e30] c0000000000095f0 ret_from_kernel_thread+0x5c/0x6c
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman at linux.vnet.ibm.com>
> Cc: Brian King <brking at linux.vnet.ibm.com>
> Cc: Keith Busch <keith.busch at intel.com>
> Cc: linux-nvme at lists.infradead.org
> ---
>  drivers/nvme/host/pci.c | 20 ++++++++------------
>  1 file changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index befac5b..cf38fe4 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1561,15 +1561,10 @@ static void nvme_disable_io_queues(struct nvme_dev *dev)
>  		reinit_completion(&dev->ioq_wait);
>   retry:
>  		timeout = ADMIN_TIMEOUT;
> -		for (; i > 0; i--) {
> -			struct nvme_queue *nvmeq = dev->queues[i];
> -
> -			if (!pass)
> -				nvme_suspend_queue(nvmeq);
> -			if (nvme_delete_queue(nvmeq, opcode))
> +		for (; i > 0; i--, sent++)
> +			if (nvme_delete_queue(dev->queues[i], opcode))
>  				break;
> -			++sent;
> -		}
> +
>  		while (sent--) {
>  			timeout = wait_for_completion_io_timeout(&dev->ioq_wait, timeout);
>  			if (timeout == 0)
> @@ -1716,11 +1711,12 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
>  		nvme_stop_queues(&dev->ctrl);
>  		csts = readl(dev->bar + NVME_REG_CSTS);
>  	}
> +
> +	for (i = dev->queue_count - 1; i > 0; i--)
> +		nvme_suspend_queue(dev->queues[i]);
> +
>  	if (csts & NVME_CSTS_CFS || !(csts & NVME_CSTS_RDY)) {
> -		for (i = dev->queue_count - 1; i >= 0; i--) {
> -			struct nvme_queue *nvmeq = dev->queues[i];
> -			nvme_suspend_queue(nvmeq);
> -		}
> +		nvme_suspend_queue(dev->queues[0]);
>  	} else {
>  		nvme_disable_io_queues(dev);
>  		nvme_disable_admin_queue(dev, shutdown);
> -- 
> 2.7.4