[PATCH] efinet: retransmit if our device is busy

[Josef Bacik <jbacik@fb.com>]

When I fixed the txbuf handling I ripped out the retransmission code since it
was flooding our network when we had the buggy behavior.  Turns out this was too
heavy handed as we can still have transient tx timeouts.  So instead make sure
we retry our transmission once per timeout.  This way we can deal with transient
transmission problems without flooding the box.  This fixes an issue we were
seeing in production.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
---
 grub-core/net/drivers/efi/efinet.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/grub-core/net/drivers/efi/efinet.c b/grub-core/net/drivers/efi/efinet.c
index 692d5ad..c8f80a1 100644
--- a/grub-core/net/drivers/efi/efinet.c
+++ b/grub-core/net/drivers/efi/efinet.c
@@ -38,6 +38,7 @@ send_card_buffer (struct grub_net_card *dev,
   grub_efi_simple_network_t *net = dev->efi_net;
   grub_uint64_t limit_time = grub_get_time_ms () + 4000;
   void *txbuf;
+  int retry = 0;
 
   if (dev->txbusy)
     while (1)
@@ -60,6 +61,15 @@ send_card_buffer (struct grub_net_card *dev,
 	    dev->txbusy = 0;
 	    break;
 	  }
+	if (!retry)
+	  {
+	    st = efi_call_7 (net->transmit, net, 0, dev->last_pkt_size,
+			     dev->txbuf, NULL, NULL, NULL);
+	    if (st != GRUB_EFI_SUCCESS)
+	      return grub_error (GRUB_ERR_IO,
+				 N_("couldn't send network packet"));
+	    retry = 1;
+	  }
 	if (limit_time < grub_get_time_ms ())
 	  return grub_error (GRUB_ERR_TIMEOUT,
 			     N_("couldn't send network packet"));
-- 
2.1.0