3.16.7-ckt26 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Hans Westgaard Ry <hans.westgaard.ry@xxxxxxxxxx>
commit 5f74f82ea34c0da80ea0b49192bb5ea06e063593 upstream.
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@xxxxxxxxxx>
Reviewed-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
include/linux/skbuff.h | 1 +
net/core/skbuff.c | 2 ++
net/core/sysctl_net_core.c | 10 ++++++++++
net/ipv4/tcp.c | 4 ++--
4 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 010bc80be91c..c046cb92172e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -169,6 +169,7 @@ struct sk_buff;
#else
#define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
#endif
+extern int sysctl_max_skb_frags;
typedef struct skb_frag_struct skb_frag_t;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7e31a99e0ed9..8c5409067930 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -77,6 +77,8 @@
struct kmem_cache *skbuff_head_cache __read_mostly;
static struct kmem_cache *skbuff_fclone_cache __read_mostly;
+int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
+EXPORT_SYMBOL(sysctl_max_skb_frags);
/**
* skb_panic - private function for out-of-line support
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index e731c96eac4b..cd386d2fd039 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -27,6 +27,7 @@ static int one = 1;
static int ushort_max = USHRT_MAX;
static int min_sndbuf = SOCK_MIN_SNDBUF;
static int min_rcvbuf = SOCK_MIN_RCVBUF;
+static int max_skb_frags = MAX_SKB_FRAGS;
#ifdef CONFIG_RPS
static int rps_sock_flow_sysctl(struct ctl_table *table, int write,
@@ -363,6 +364,15 @@ static struct ctl_table net_core_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec
},
+ {
+ .procname = "max_skb_frags",
+ .data = &sysctl_max_skb_frags,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
+ .extra2 = &max_skb_frags,
+ },
{ }
};
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9c4f0d2f2892..9ee5a4bbb289 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -929,7 +929,7 @@ 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;
}
--
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