nvme/pci: Poll CQ on timeout

If an IO timeout occurs, it's helpful to know if the controller did not
post a completion or the driver missed an interrupt. While we never expect
the latter, this patch will make it possible to tell the difference so
we don't have to guess.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index a363fecb8d8256f16d9ca1a047358fba8856224e..212f7e0db84ffcbc26a3c76b43bb6de971ac1ab0 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -846,10 +846,8 @@ static irqreturn_t nvme_irq_check(int irq, void *data)
        return IRQ_NONE;
 }
 
-static int nvme_poll(struct blk_mq_hw_ctx *hctx, unsigned int tag)
+static int __nvme_poll(struct nvme_queue *nvmeq, unsigned int tag)
 {
-       struct nvme_queue *nvmeq = hctx->driver_data;
-
        if (nvme_cqe_valid(nvmeq, nvmeq->cq_head, nvmeq->cq_phase)) {
                spin_lock_irq(&nvmeq->q_lock);
                __nvme_process_cq(nvmeq, &tag);
@@ -862,6 +860,13 @@ static int nvme_poll(struct blk_mq_hw_ctx *hctx, unsigned int tag)
        return 0;
 }
 
+static int nvme_poll(struct blk_mq_hw_ctx *hctx, unsigned int tag)
+{
+       struct nvme_queue *nvmeq = hctx->driver_data;
+
+       return __nvme_poll(nvmeq, tag);
+}
+
 static void nvme_pci_submit_async_event(struct nvme_ctrl *ctrl, int aer_idx)
 {
        struct nvme_dev *dev = to_nvme_dev(ctrl);
@@ -959,6 +964,16 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req, bool reserved)
        struct request *abort_req;
        struct nvme_command cmd;
 
+       /*
+        * Did we miss an interrupt?
+        */
+       if (__nvme_poll(nvmeq, req->tag)) {
+               dev_warn(dev->ctrl.device,
+                        "I/O %d QID %d timeout, completion polled\n",
+                        req->tag, nvmeq->qid);
+               return BLK_EH_HANDLED;
+       }
+
        /*
         * Shutdown immediately if controller times out while starting. The
         * reset work will see the pci device disabled when it gets the forced