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authorPatrick McHardy <kaber@trash.net>2013-04-17 06:47:02 +0000
committerDavid S. Miller <davem@davemloft.net>2013-04-19 14:57:57 -0400
commit9652e931e73be7e54a9c40e9bcd4bbdafe92a406 (patch)
treeb943a75e53e22e9dcdb26558d971ac25af566a02 /net/netlink
parentccdfcc398594ddf3f77348c5a10938dbe9efefbe (diff)
downloadlinux-9652e931e73be7e54a9c40e9bcd4bbdafe92a406.tar.gz
netlink: add mmap'ed netlink helper functions
Add helper functions for looking up mmap'ed frame headers, reading and writing their status, allocating skbs with mmap'ed data areas and a poll function. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink')
-rw-r--r--net/netlink/af_netlink.c185
1 files changed, 183 insertions, 2 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 1d3c7128e90..6560635fd25 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -56,6 +56,7 @@
#include <linux/audit.h>
#include <linux/mutex.h>
#include <linux/vmalloc.h>
+#include <asm/cacheflush.h>
#include <net/net_namespace.h>
#include <net/sock.h>
@@ -89,6 +90,7 @@ EXPORT_SYMBOL_GPL(nl_table);
static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
static int netlink_dump(struct sock *sk);
+static void netlink_skb_destructor(struct sk_buff *skb);
DEFINE_RWLOCK(nl_table_lock);
EXPORT_SYMBOL_GPL(nl_table_lock);
@@ -109,6 +111,11 @@ static inline struct hlist_head *nl_portid_hashfn(struct nl_portid_hash *hash, u
}
#ifdef CONFIG_NETLINK_MMAP
+static bool netlink_skb_is_mmaped(const struct sk_buff *skb)
+{
+ return NETLINK_CB(skb).flags & NETLINK_SKB_MMAPED;
+}
+
static __pure struct page *pgvec_to_page(const void *addr)
{
if (is_vmalloc_addr(addr))
@@ -332,8 +339,154 @@ out:
mutex_unlock(&nlk->pg_vec_lock);
return 0;
}
+
+static void netlink_frame_flush_dcache(const struct nl_mmap_hdr *hdr)
+{
+#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 1
+ struct page *p_start, *p_end;
+
+ /* First page is flushed through netlink_{get,set}_status */
+ p_start = pgvec_to_page(hdr + PAGE_SIZE);
+ p_end = pgvec_to_page((void *)hdr + NL_MMAP_MSG_HDRLEN + hdr->nm_len - 1);
+ while (p_start <= p_end) {
+ flush_dcache_page(p_start);
+ p_start++;
+ }
+#endif
+}
+
+static enum nl_mmap_status netlink_get_status(const struct nl_mmap_hdr *hdr)
+{
+ smp_rmb();
+ flush_dcache_page(pgvec_to_page(hdr));
+ return hdr->nm_status;
+}
+
+static void netlink_set_status(struct nl_mmap_hdr *hdr,
+ enum nl_mmap_status status)
+{
+ hdr->nm_status = status;
+ flush_dcache_page(pgvec_to_page(hdr));
+ smp_wmb();
+}
+
+static struct nl_mmap_hdr *
+__netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos)
+{
+ unsigned int pg_vec_pos, frame_off;
+
+ pg_vec_pos = pos / ring->frames_per_block;
+ frame_off = pos % ring->frames_per_block;
+
+ return ring->pg_vec[pg_vec_pos] + (frame_off * ring->frame_size);
+}
+
+static struct nl_mmap_hdr *
+netlink_lookup_frame(const struct netlink_ring *ring, unsigned int pos,
+ enum nl_mmap_status status)
+{
+ struct nl_mmap_hdr *hdr;
+
+ hdr = __netlink_lookup_frame(ring, pos);
+ if (netlink_get_status(hdr) != status)
+ return NULL;
+
+ return hdr;
+}
+
+static struct nl_mmap_hdr *
+netlink_current_frame(const struct netlink_ring *ring,
+ enum nl_mmap_status status)
+{
+ return netlink_lookup_frame(ring, ring->head, status);
+}
+
+static struct nl_mmap_hdr *
+netlink_previous_frame(const struct netlink_ring *ring,
+ enum nl_mmap_status status)
+{
+ unsigned int prev;
+
+ prev = ring->head ? ring->head - 1 : ring->frame_max;
+ return netlink_lookup_frame(ring, prev, status);
+}
+
+static void netlink_increment_head(struct netlink_ring *ring)
+{
+ ring->head = ring->head != ring->frame_max ? ring->head + 1 : 0;
+}
+
+static void netlink_forward_ring(struct netlink_ring *ring)
+{
+ unsigned int head = ring->head, pos = head;
+ const struct nl_mmap_hdr *hdr;
+
+ do {
+ hdr = __netlink_lookup_frame(ring, pos);
+ if (hdr->nm_status == NL_MMAP_STATUS_UNUSED)
+ break;
+ if (hdr->nm_status != NL_MMAP_STATUS_SKIP)
+ break;
+ netlink_increment_head(ring);
+ } while (ring->head != head);
+}
+
+static unsigned int netlink_poll(struct file *file, struct socket *sock,
+ poll_table *wait)
+{
+ struct sock *sk = sock->sk;
+ struct netlink_sock *nlk = nlk_sk(sk);
+ unsigned int mask;
+
+ mask = datagram_poll(file, sock, wait);
+
+ spin_lock_bh(&sk->sk_receive_queue.lock);
+ if (nlk->rx_ring.pg_vec) {
+ netlink_forward_ring(&nlk->rx_ring);
+ if (!netlink_previous_frame(&nlk->rx_ring, NL_MMAP_STATUS_UNUSED))
+ mask |= POLLIN | POLLRDNORM;
+ }
+ spin_unlock_bh(&sk->sk_receive_queue.lock);
+
+ spin_lock_bh(&sk->sk_write_queue.lock);
+ if (nlk->tx_ring.pg_vec) {
+ if (netlink_current_frame(&nlk->tx_ring, NL_MMAP_STATUS_UNUSED))
+ mask |= POLLOUT | POLLWRNORM;
+ }
+ spin_unlock_bh(&sk->sk_write_queue.lock);
+
+ return mask;
+}
+
+static struct nl_mmap_hdr *netlink_mmap_hdr(struct sk_buff *skb)
+{
+ return (struct nl_mmap_hdr *)(skb->head - NL_MMAP_HDRLEN);
+}
+
+static void netlink_ring_setup_skb(struct sk_buff *skb, struct sock *sk,
+ struct netlink_ring *ring,
+ struct nl_mmap_hdr *hdr)
+{
+ unsigned int size;
+ void *data;
+
+ size = ring->frame_size - NL_MMAP_HDRLEN;
+ data = (void *)hdr + NL_MMAP_HDRLEN;
+
+ skb->head = data;
+ skb->data = data;
+ skb_reset_tail_pointer(skb);
+ skb->end = skb->tail + size;
+ skb->len = 0;
+
+ skb->destructor = netlink_skb_destructor;
+ NETLINK_CB(skb).flags |= NETLINK_SKB_MMAPED;
+ NETLINK_CB(skb).sk = sk;
+}
#else /* CONFIG_NETLINK_MMAP */
+#define netlink_skb_is_mmaped(skb) false
#define netlink_mmap sock_no_mmap
+#define netlink_poll datagram_poll
#endif /* CONFIG_NETLINK_MMAP */
static void netlink_destroy_callback(struct netlink_callback *cb)
@@ -350,7 +503,35 @@ static void netlink_consume_callback(struct netlink_callback *cb)
static void netlink_skb_destructor(struct sk_buff *skb)
{
- sock_rfree(skb);
+#ifdef CONFIG_NETLINK_MMAP
+ struct nl_mmap_hdr *hdr;
+ struct netlink_ring *ring;
+ struct sock *sk;
+
+ /* If a packet from the kernel to userspace was freed because of an
+ * error without being delivered to userspace, the kernel must reset
+ * the status. In the direction userspace to kernel, the status is
+ * always reset here after the packet was processed and freed.
+ */
+ if (netlink_skb_is_mmaped(skb)) {
+ hdr = netlink_mmap_hdr(skb);
+ sk = NETLINK_CB(skb).sk;
+
+ if (!(NETLINK_CB(skb).flags & NETLINK_SKB_DELIVERED)) {
+ hdr->nm_len = 0;
+ netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
+ }
+ ring = &nlk_sk(sk)->rx_ring;
+
+ WARN_ON(atomic_read(&ring->pending) == 0);
+ atomic_dec(&ring->pending);
+ sock_put(sk);
+
+ skb->data = NULL;
+ }
+#endif
+ if (skb->sk != NULL)
+ sock_rfree(skb);
}
static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
@@ -2349,7 +2530,7 @@ static const struct proto_ops netlink_ops = {
.socketpair = sock_no_socketpair,
.accept = sock_no_accept,
.getname = netlink_getname,
- .poll = datagram_poll,
+ .poll = netlink_poll,
.ioctl = sock_no_ioctl,
.listen = sock_no_listen,
.shutdown = sock_no_shutdown,