Commit 541cc07f authored by Hans Westgaard Ry's avatar Hans Westgaard Ry Committed by Kamal Mostafa

net:Add sysctl_max_skb_frags

commit 5f74f82e 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: default avatarHans Westgaard Ry <hans.westgaard.ry@oracle.com>
Reviewed-by: default avatarHåkon Bugge <haakon.bugge@oracle.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
parent 79cd94bc
......@@ -148,6 +148,7 @@ 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;
......
......@@ -75,6 +75,8 @@
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
......
......@@ -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,
......@@ -362,6 +363,15 @@ 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,
},
{ }
};
......
......@@ -887,7 +887,7 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
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;
}
......@@ -1170,7 +1170,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
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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