nvme: fix irq vs io_queue calculations

Guenter reported an boot hang issue on HPPA after we default to 0 poll
queues. We have two issues in the queue count calculations:

1) We don't separate the poll queues from the read/write queues. This is
   important, since the former doesn't need interrupts.
2) The adjust logic is broken.

Adjust the poll queue count before doing nvme_calc_io_queues(). The poll
queue count is only limited by the IO queue count we were able to get
from the controller, not failures in the IRQ allocation loop. This
leaves nvme_calc_io_queues() just adjusting the read/write queue map.

Reported-by: Reported-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 7732c49..fb9d827 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2030,60 +2030,40 @@ static int nvme_setup_host_mem(struct nvme_dev *dev)
        return ret;
 }
 
-static void nvme_calc_io_queues(struct nvme_dev *dev, unsigned int nr_io_queues)
+static void nvme_calc_io_queues(struct nvme_dev *dev, unsigned int irq_queues)
 {
        unsigned int this_w_queues = write_queues;
-       unsigned int this_p_queues = poll_queues;
 
        /*
         * Setup read/write queue split
         */
-       if (nr_io_queues == 1) {
+       if (irq_queues == 1) {
                dev->io_queues[HCTX_TYPE_DEFAULT] = 1;
                dev->io_queues[HCTX_TYPE_READ] = 0;
-               dev->io_queues[HCTX_TYPE_POLL] = 0;
                return;
        }
 
-       /*
-        * Configure number of poll queues, if set
-        */
-       if (this_p_queues) {
-               /*
-                * We need at least one queue left. With just one queue, we'll
-                * have a single shared read/write set.
-                */
-               if (this_p_queues >= nr_io_queues) {
-                       this_w_queues = 0;
-                       this_p_queues = nr_io_queues - 1;
-               }
-
-               dev->io_queues[HCTX_TYPE_POLL] = this_p_queues;
-               nr_io_queues -= this_p_queues;
-       } else
-               dev->io_queues[HCTX_TYPE_POLL] = 0;
-
        /*
         * If 'write_queues' is set, ensure it leaves room for at least
         * one read queue
         */
-       if (this_w_queues >= nr_io_queues)
-               this_w_queues = nr_io_queues - 1;
+       if (this_w_queues >= irq_queues)
+               this_w_queues = irq_queues - 1;
 
        /*
         * If 'write_queues' is set to zero, reads and writes will share
         * a queue set.
         */
        if (!this_w_queues) {
-               dev->io_queues[HCTX_TYPE_DEFAULT] = nr_io_queues;
+               dev->io_queues[HCTX_TYPE_DEFAULT] = irq_queues;
                dev->io_queues[HCTX_TYPE_READ] = 0;
        } else {
                dev->io_queues[HCTX_TYPE_DEFAULT] = this_w_queues;
-               dev->io_queues[HCTX_TYPE_READ] = nr_io_queues - this_w_queues;
+               dev->io_queues[HCTX_TYPE_READ] = irq_queues - this_w_queues;
        }
 }
 
-static int nvme_setup_irqs(struct nvme_dev *dev, int nr_io_queues)
+static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues)
 {
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int irq_sets[2];
@@ -2093,6 +2073,20 @@ static int nvme_setup_irqs(struct nvme_dev *dev, int nr_io_queues)
                .sets = irq_sets,
        };
        int result = 0;
+       unsigned int irq_queues, this_p_queues;
+
+       /*
+        * Poll queues don't need interrupts, but we need at least one IO
+        * queue left over for non-polled IO.
+        */
+       this_p_queues = poll_queues;
+       if (this_p_queues >= nr_io_queues) {
+               this_p_queues = nr_io_queues - 1;
+               irq_queues = 1;
+       } else {
+               irq_queues = nr_io_queues - this_p_queues;
+       }
+       dev->io_queues[HCTX_TYPE_POLL] = this_p_queues;
 
        /*
         * For irq sets, we have to ask for minvec == maxvec. This passes
@@ -2100,7 +2094,7 @@ static int nvme_setup_irqs(struct nvme_dev *dev, int nr_io_queues)
         * IRQ vector needs.
         */
        do {
-               nvme_calc_io_queues(dev, nr_io_queues);
+               nvme_calc_io_queues(dev, irq_queues);
                irq_sets[0] = dev->io_queues[HCTX_TYPE_DEFAULT];
                irq_sets[1] = dev->io_queues[HCTX_TYPE_READ];
                if (!irq_sets[1])
@@ -2111,11 +2105,11 @@ static int nvme_setup_irqs(struct nvme_dev *dev, int nr_io_queues)
                 * 1 + 1 queues, just ask for a single vector. We'll share
                 * that between the single IO queue and the admin queue.
                 */
-               if (!(result < 0 && nr_io_queues == 1))
-                       nr_io_queues = irq_sets[0] + irq_sets[1] + 1;
+               if (result >= 0 && irq_queues > 1)
+                       irq_queues = irq_sets[0] + irq_sets[1] + 1;
 
-               result = pci_alloc_irq_vectors_affinity(pdev, nr_io_queues,
-                               nr_io_queues,
+               result = pci_alloc_irq_vectors_affinity(pdev, irq_queues,
+                               irq_queues,
                                PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd);
 
                /*
@@ -2125,12 +2119,12 @@ static int nvme_setup_irqs(struct nvme_dev *dev, int nr_io_queues)
                 * likely does not. Back down to ask for just one vector.
                 */
                if (result == -ENOSPC) {
-                       nr_io_queues--;
-                       if (!nr_io_queues)
+                       irq_queues--;
+                       if (!irq_queues)
                                return result;
                        continue;
                } else if (result == -EINVAL) {
-                       nr_io_queues = 1;
+                       irq_queues = 1;
                        continue;
                } else if (result <= 0)
                        return -EIO;