NVMe: Call nvme_free_queue directly

Rather than relying on call_rcu, this patch directly frees the
nvme_queue's memory after ensuring no readers exist. Some arch specific
dma_free_coherent implementations may not be called from a call_rcu's
soft interrupt context, hence the change.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reported-by: Matthew Minter <matthew_minter@xyratex.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 3ada636356e82796fd7531b30a6d1420162e8223..d3a025fc126860b6aff7721b1faedd8c5be86edf 100644 (file)
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -95,7 +95,7 @@ struct async_cmd_info {
  * commands and one for I/O commands).
  */
 struct nvme_queue {
-       struct rcu_head r_head;
+       struct llist_node node;
        struct device *q_dmadev;
        struct nvme_dev *dev;
        char irqname[24];       /* nvme4294967295-65535\0 */
@@ -1192,10 +1192,8 @@ static void nvme_cancel_ios(struct nvme_queue *nvmeq, bool timeout)
        }
 }
 
-static void nvme_free_queue(struct rcu_head *r)
+static void nvme_free_queue(struct nvme_queue *nvmeq)
 {
-       struct nvme_queue *nvmeq = container_of(r, struct nvme_queue, r_head);
-
        spin_lock_irq(&nvmeq->q_lock);
        while (bio_list_peek(&nvmeq->sq_cong)) {
                struct bio *bio = bio_list_pop(&nvmeq->sq_cong);
@@ -1225,14 +1223,21 @@ static void nvme_free_queue(struct rcu_head *r)
 
 static void nvme_free_queues(struct nvme_dev *dev, int lowest)
 {
+       LLIST_HEAD(q_list);
+       struct nvme_queue *nvmeq, *next;
+       struct llist_node *entry;
        int i;
 
        for (i = dev->queue_count - 1; i >= lowest; i--) {
-               struct nvme_queue *nvmeq = raw_nvmeq(dev, i);
+               nvmeq = raw_nvmeq(dev, i);
                rcu_assign_pointer(dev->queues[i], NULL);
-               call_rcu(&nvmeq->r_head, nvme_free_queue);
+               llist_add(&nvmeq->node, &q_list);
                dev->queue_count--;
        }
+       synchronize_rcu();
+       entry = llist_del_all(&q_list);
+       llist_for_each_entry_safe(nvmeq, next, entry, node)
+               nvme_free_queue(nvmeq);
 }
 
 /**
@@ -2929,7 +2934,6 @@ static void nvme_remove(struct pci_dev *pdev)
        nvme_dev_remove(dev);
        nvme_dev_shutdown(dev);
        nvme_free_queues(dev, 0);
-       rcu_barrier();
        nvme_release_instance(dev);
        nvme_release_prp_pools(dev);
        kref_put(&dev->kref, nvme_free_dev);