net:Add sysctl_max_skb_frags

Devices may have limits on the number of fragments in an skb they support.
Current codebase uses a constant as maximum for number of fragments one
skb can hold and use.
When enabling scatter/gather and running traffic with many small messages
the codebase uses the maximum number of fragments and may thereby violate
the max for certain devices.
The patch introduces a global variable as max number of fragments.

Signed-off-by: Hans Westgaard Ry <hans.westgaard.ry@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 19746b3fcbbe..0c36ef4a3f86 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -940,7 +940,7 @@ new_segment:
 
                 i = skb_shinfo(skb)->nr_frags;
                 can_coalesce = skb_can_coalesce(skb, i, page, offset);
-                if (!can_coalesce && i >= MAX_SKB_FRAGS) {
+                if (!can_coalesce && i >= sysctl_max_skb_frags) {
                         tcp_mark_push(tp, skb);
                         goto new_segment;
                 }
@@ -1213,7 +1213,7 @@ new_segment:
 
                         if (!skb_can_coalesce(skb, i, pfrag->page,
                                               pfrag->offset)) {
-                                if (i == MAX_SKB_FRAGS || !sg) {
+                                if (i == sysctl_max_skb_frags || !sg) {
                                         tcp_mark_push(tp, skb);
                                         goto new_segment;
                                 }