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authorDave Jiang <dave.jiang@intel.com>2015-07-13 08:07:17 -0400
committerJon Mason <jdmason@kudzu.us>2015-09-07 15:17:08 -0400
commite74bfeedad08180b968d8613dcde141ffb0720c3 (patch)
tree989c37a03defc84cd2db4ed121bf633ebb074632 /drivers/ntb/ntb_transport.c
parent5e9fd733fa34b491e7ac41c91aa42ba0a9d8ea10 (diff)
NTB: Add flow control to the ntb_netdev
Right now if we push the NTB really hard, we start dropping packets due to not able to process the packets fast enough. We need to st:qop the upper layer from flooding us when that happens. A timer is necessary in order to restart the queue once the resource has been processed on the receive side. Due to the way NTB is setup, the resources on the tx side are tied to the processing of the rx side and there's no async way to know when the rx side has released those resources. Signed-off-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Jon Mason <jdmason@kudzu.us>
Diffstat (limited to 'drivers/ntb/ntb_transport.c')
-rw-r--r--drivers/ntb/ntb_transport.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
index 1c6386d5f79c..0d851d684523 100644
--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -494,6 +494,12 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count,
"tx_index - \t%u\n", qp->tx_index);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"tx_max_entry - \t%u\n", qp->tx_max_entry);
+ out_offset += snprintf(buf + out_offset, out_count - out_offset,
+ "qp->remote_rx_info->entry - \t%u\n",
+ qp->remote_rx_info->entry);
+ out_offset += snprintf(buf + out_offset, out_count - out_offset,
+ "free tx - \t%u\n",
+ ntb_transport_tx_free_entry(qp));
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"\nQP Link %s\n",
@@ -535,6 +541,7 @@ static struct ntb_queue_entry *ntb_list_rm(spinlock_t *lock,
}
entry = list_first_entry(list, struct ntb_queue_entry, entry);
list_del(&entry->entry);
+
out:
spin_unlock_irqrestore(lock, flags);
@@ -1843,7 +1850,7 @@ int ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data,
entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q);
if (!entry) {
qp->tx_err_no_buf++;
- return -ENOMEM;
+ return -EBUSY;
}
entry->cb_data = cb;
@@ -1969,6 +1976,15 @@ unsigned int ntb_transport_max_size(struct ntb_transport_qp *qp)
}
EXPORT_SYMBOL_GPL(ntb_transport_max_size);
+unsigned int ntb_transport_tx_free_entry(struct ntb_transport_qp *qp)
+{
+ unsigned int head = qp->tx_index;
+ unsigned int tail = qp->remote_rx_info->entry;
+
+ return tail > head ? tail - head : qp->tx_max_entry + tail - head;
+}
+EXPORT_SYMBOL_GPL(ntb_transport_tx_free_entry);
+
static void ntb_transport_doorbell_callback(void *data, int vector)
{
struct ntb_transport_ctx *nt = data;