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[PATCH V2 4/4] ofnet: implement the receive buffer


From: Stanislav Kholmanskikh
Subject: [PATCH V2 4/4] ofnet: implement the receive buffer
Date: Fri, 2 Dec 2016 18:10:05 +0300

get_card_packet() from ofnet.c allocates a netbuff based on the device's MTU:

 nb = grub_netbuff_alloc (dev->mtu + 64 + 2);

In the case when the MTU is large, and the received packet is
relatively small, this leads to allocation of significantly more memory,
than it's required. An example could be transmission of TFTP packets
with 0x400 blksize via a network card with 0x10000 MTU.

This patch implements a per-card receive buffer in a way similar to efinet.c,
and makes get_card_packet() allocate a netbuff of the received data size.

Signed-off-by: Stanislav Kholmanskikh <address@hidden>
---
 grub-core/net/drivers/ieee1275/ofnet.c |   50 ++++++++++++++++++++++---------
 1 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/grub-core/net/drivers/ieee1275/ofnet.c 
b/grub-core/net/drivers/ieee1275/ofnet.c
index 1f8ac9a..471b87b 100644
--- a/grub-core/net/drivers/ieee1275/ofnet.c
+++ b/grub-core/net/drivers/ieee1275/ofnet.c
@@ -85,9 +85,18 @@ get_card_packet (struct grub_net_card *dev)
   grub_uint64_t start_time;
   struct grub_net_buff *nb;
 
-  nb = grub_netbuff_alloc (dev->mtu + 64 + 2);
+  start_time = grub_get_time_ms ();
+  do
+    rc = grub_ieee1275_read (data->handle, dev->rcvbuf, dev->rcvbufsize, 
&actual);
+  while ((actual <= 0 || rc < 0) && (grub_get_time_ms () - start_time < 200));
+
+  if (actual <= 0)
+    return NULL;
+
+  nb = grub_netbuff_alloc (actual + 2);
   if (!nb)
     return NULL;
+
   /* Reserve 2 bytes so that 2 + 14/18 bytes of ethernet header is divisible
      by 4. So that IP header is aligned on 4 bytes. */
   if (grub_netbuff_reserve (nb, 2))
@@ -96,17 +105,15 @@ get_card_packet (struct grub_net_card *dev)
       return NULL;
     }
 
-  start_time = grub_get_time_ms ();
-  do
-    rc = grub_ieee1275_read (data->handle, nb->data, dev->mtu + 64, &actual);
-  while ((actual <= 0 || rc < 0) && (grub_get_time_ms () - start_time < 200));
-  if (actual > 0)
+  grub_memcpy (nb->data, dev->rcvbuf, actual);
+
+  if (grub_netbuff_put (nb, actual))
     {
-      grub_netbuff_put (nb, actual);
-      return nb;
+      grub_netbuff_free (nb);
+      return NULL;
     }
-  grub_netbuff_free (nb);
-  return NULL;
+
+  return nb;
 }
 
 static struct grub_net_card_driver ofdriver =
@@ -498,16 +505,21 @@ search_net_devices (struct grub_ieee1275_devalias *alias)
   card->default_address = lla;
 
   card->txbufsize = ALIGN_UP (card->mtu, 64) + 256;
+  card->rcvbufsize = ALIGN_UP (card->mtu, 64) + 256;
 
   card->txbuf = ofnet_alloc_netbuf (card->txbufsize);
   if (!card->txbuf)
+    goto fail_netbuf;
+
+  card->rcvbuf = ofnet_alloc_netbuf (card->rcvbufsize);
+  if (!card->rcvbuf)
     {
-      grub_free (ofdata->path);
-      grub_free (ofdata);
-      grub_free (card);
-      grub_print_error ();
-      return 1;
+      grub_error_push ();
+      ofnet_free_netbuf(card->txbuf, card->txbufsize);
+      grub_error_pop ();
+      goto fail_netbuf;
     }
+  
   card->driver = NULL;
   card->data = ofdata;
   card->flags = 0;
@@ -519,6 +531,13 @@ search_net_devices (struct grub_ieee1275_devalias *alias)
   card->driver = &ofdriver;
   grub_net_card_register (card);
   return 0;
+
+fail_netbuf:
+  grub_free (ofdata->path);
+  grub_free (ofdata);
+  grub_free (card);
+  grub_print_error ();
+  return 1;
 }
 
 static void
@@ -553,6 +572,7 @@ GRUB_MOD_FINI(ofnet)
        grub_free (ofdata);
 
        ofnet_free_netbuf (card->txbuf, card->txbufsize);
+       ofnet_free_netbuf (card->rcvbuf, card->rcvbufsize);
 
        grub_free ((void *) card->name);
        grub_free (card);
-- 
1.7.1




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