nvme-pci: fix race condition between reset and nvme_dev_disable()

In the Linux kernel, the following vulnerability has been resolved:

nvme-pci: fix race condition between reset and nvme_dev_disable()

nvme_dev_disable() modifies the dev->online_queues field, therefore

nvme_pci_update_nr_queues() should avoid racing against it, otherwise

we could end up passing invalid values to blk_mq_update_nr_hw_queues().

WARNING: CPU: 39 PID: 61303 at drivers/pci/msi/api.c:347

pci_irq_get_affinity+0x187/0x210

Workqueue: nvme-reset-wq nvme_reset_work [nvme]

RIP: 0010:pci_irq_get_affinity+0x187/0x210

Call Trace:

<TASK>

? blk_mq_pci_map_queues+0x87/0x3c0

? pci_irq_get_affinity+0x187/0x210

blk_mq_pci_map_queues+0x87/0x3c0

nvme_pci_map_queues+0x189/0x460 [nvme]

blk_mq_update_nr_hw_queues+0x2a/0x40

nvme_reset_work+0x1be/0x2a0 [nvme]

Fix the bug by locking the shutdown_lock mutex before using

dev->online_queues. Give up if nvme_dev_disable() is running or if

it has been executed already.