+++ /dev/null
-This file documents how to use memory mapped I/O with netlink.
-
-Author: Patrick McHardy <kaber@trash.net>
-
-Overview
---------
-
-Memory mapped netlink I/O can be used to increase throughput and decrease
-overhead of unicast receive and transmit operations. Some netlink subsystems
-require high throughput, these are mainly the netfilter subsystems
-nfnetlink_queue and nfnetlink_log, but it can also help speed up large
-dump operations of f.i. the routing database.
-
-Memory mapped netlink I/O used two circular ring buffers for RX and TX which
-are mapped into the processes address space.
-
-The RX ring is used by the kernel to directly construct netlink messages into
-user-space memory without copying them as done with regular socket I/O,
-additionally as long as the ring contains messages no recvmsg() or poll()
-syscalls have to be issued by user-space to get more message.
-
-The TX ring is used to process messages directly from user-space memory, the
-kernel processes all messages contained in the ring using a single sendmsg()
-call.
-
-Usage overview
---------------
-
-In order to use memory mapped netlink I/O, user-space needs three main changes:
-
-- ring setup
-- conversion of the RX path to get messages from the ring instead of recvmsg()
-- conversion of the TX path to construct messages into the ring
-
-Ring setup is done using setsockopt() to provide the ring parameters to the
-kernel, then a call to mmap() to map the ring into the processes address space:
-
-- setsockopt(fd, SOL_NETLINK, NETLINK_RX_RING, ¶ms, sizeof(params));
-- setsockopt(fd, SOL_NETLINK, NETLINK_TX_RING, ¶ms, sizeof(params));
-- ring = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)
-
-Usage of either ring is optional, but even if only the RX ring is used the
-mapping still needs to be writable in order to update the frame status after
-processing.
-
-Conversion of the reception path involves calling poll() on the file
-descriptor, once the socket is readable the frames from the ring are
-processed in order until no more messages are available, as indicated by
-a status word in the frame header.
-
-On kernel side, in order to make use of memory mapped I/O on receive, the
-originating netlink subsystem needs to support memory mapped I/O, otherwise
-it will use an allocated socket buffer as usual and the contents will be
- copied to the ring on transmission, nullifying most of the performance gains.
-Dumps of kernel databases automatically support memory mapped I/O.
-
-Conversion of the transmit path involves changing message construction to
-use memory from the TX ring instead of (usually) a buffer declared on the
-stack and setting up the frame header appropriately. Optionally poll() can
-be used to wait for free frames in the TX ring.
-
-Structured and definitions for using memory mapped I/O are contained in
-<linux/netlink.h>.
-
-RX and TX rings
-----------------
-
-Each ring contains a number of continuous memory blocks, containing frames of
-fixed size dependent on the parameters used for ring setup.
-
-Ring: [ block 0 ]
- [ frame 0 ]
- [ frame 1 ]
- [ block 1 ]
- [ frame 2 ]
- [ frame 3 ]
- ...
- [ block n ]
- [ frame 2 * n ]
- [ frame 2 * n + 1 ]
-
-The blocks are only visible to the kernel, from the point of view of user-space
-the ring just contains the frames in a continuous memory zone.
-
-The ring parameters used for setting up the ring are defined as follows:
-
-struct nl_mmap_req {
- unsigned int nm_block_size;
- unsigned int nm_block_nr;
- unsigned int nm_frame_size;
- unsigned int nm_frame_nr;
-};
-
-Frames are grouped into blocks, where each block is a continuous region of memory
-and holds nm_block_size / nm_frame_size frames. The total number of frames in
-the ring is nm_frame_nr. The following invariants hold:
-
-- frames_per_block = nm_block_size / nm_frame_size
-
-- nm_frame_nr = frames_per_block * nm_block_nr
-
-Some parameters are constrained, specifically:
-
-- nm_block_size must be a multiple of the architectures memory page size.
- The getpagesize() function can be used to get the page size.
-
-- nm_frame_size must be equal or larger to NL_MMAP_HDRLEN, IOW a frame must be
- able to hold at least the frame header
-
-- nm_frame_size must be smaller or equal to nm_block_size
-
-- nm_frame_size must be a multiple of NL_MMAP_MSG_ALIGNMENT
-
-- nm_frame_nr must equal the actual number of frames as specified above.
-
-When the kernel can't allocate physically continuous memory for a ring block,
-it will fall back to use physically discontinuous memory. This might affect
-performance negatively, in order to avoid this the nm_frame_size parameter
-should be chosen to be as small as possible for the required frame size and
-the number of blocks should be increased instead.
-
-Ring frames
-------------
-
-Each frames contain a frame header, consisting of a synchronization word and some
-meta-data, and the message itself.
-
-Frame: [ header message ]
-
-The frame header is defined as follows:
-
-struct nl_mmap_hdr {
- unsigned int nm_status;
- unsigned int nm_len;
- __u32 nm_group;
- /* credentials */
- __u32 nm_pid;
- __u32 nm_uid;
- __u32 nm_gid;
-};
-
-- nm_status is used for synchronizing processing between the kernel and user-
- space and specifies ownership of the frame as well as the operation to perform
-
-- nm_len contains the length of the message contained in the data area
-
-- nm_group specified the destination multicast group of message
-
-- nm_pid, nm_uid and nm_gid contain the netlink pid, UID and GID of the sending
- process. These values correspond to the data available using SOCK_PASSCRED in
- the SCM_CREDENTIALS cmsg.
-
-The possible values in the status word are:
-
-- NL_MMAP_STATUS_UNUSED:
- RX ring: frame belongs to the kernel and contains no message
- for user-space. Approriate action is to invoke poll()
- to wait for new messages.
-
- TX ring: frame belongs to user-space and can be used for
- message construction.
-
-- NL_MMAP_STATUS_RESERVED:
- RX ring only: frame is currently used by the kernel for message
- construction and contains no valid message yet.
- Appropriate action is to invoke poll() to wait for
- new messages.
-
-- NL_MMAP_STATUS_VALID:
- RX ring: frame contains a valid message. Approriate action is
- to process the message and release the frame back to
- the kernel by setting the status to
- NL_MMAP_STATUS_UNUSED or queue the frame by setting the
- status to NL_MMAP_STATUS_SKIP.
-
- TX ring: the frame contains a valid message from user-space to
- be processed by the kernel. After completing processing
- the kernel will release the frame back to user-space by
- setting the status to NL_MMAP_STATUS_UNUSED.
-
-- NL_MMAP_STATUS_COPY:
- RX ring only: a message is ready to be processed but could not be
- stored in the ring, either because it exceeded the
- frame size or because the originating subsystem does
- not support memory mapped I/O. Appropriate action is
- to invoke recvmsg() to receive the message and release
- the frame back to the kernel by setting the status to
- NL_MMAP_STATUS_UNUSED.
-
-- NL_MMAP_STATUS_SKIP:
- RX ring only: user-space queued the message for later processing, but
- processed some messages following it in the ring. The
- kernel should skip this frame when looking for unused
- frames.
-
-The data area of a frame begins at a offset of NL_MMAP_HDRLEN relative to the
-frame header.
-
-TX limitations
---------------
-
-As of Jan 2015 the message is always copied from the ring frame to an
-allocated buffer due to unresolved security concerns.
-See commit 4682a0358639b29cf ("netlink: Always copy on mmap TX.").
-
-Example
--------
-
-Ring setup:
-
- unsigned int block_size = 16 * getpagesize();
- struct nl_mmap_req req = {
- .nm_block_size = block_size,
- .nm_block_nr = 64,
- .nm_frame_size = 16384,
- .nm_frame_nr = 64 * block_size / 16384,
- };
- unsigned int ring_size;
- void *rx_ring, *tx_ring;
-
- /* Configure ring parameters */
- if (setsockopt(fd, SOL_NETLINK, NETLINK_RX_RING, &req, sizeof(req)) < 0)
- exit(1);
- if (setsockopt(fd, SOL_NETLINK, NETLINK_TX_RING, &req, sizeof(req)) < 0)
- exit(1)
-
- /* Calculate size of each individual ring */
- ring_size = req.nm_block_nr * req.nm_block_size;
-
- /* Map RX/TX rings. The TX ring is located after the RX ring */
- rx_ring = mmap(NULL, 2 * ring_size, PROT_READ | PROT_WRITE,
- MAP_SHARED, fd, 0);
- if ((long)rx_ring == -1L)
- exit(1);
- tx_ring = rx_ring + ring_size:
-
-Message reception:
-
-This example assumes some ring parameters of the ring setup are available.
-
- unsigned int frame_offset = 0;
- struct nl_mmap_hdr *hdr;
- struct nlmsghdr *nlh;
- unsigned char buf[16384];
- ssize_t len;
-
- while (1) {
- struct pollfd pfds[1];
-
- pfds[0].fd = fd;
- pfds[0].events = POLLIN | POLLERR;
- pfds[0].revents = 0;
-
- if (poll(pfds, 1, -1) < 0 && errno != -EINTR)
- exit(1);
-
- /* Check for errors. Error handling omitted */
- if (pfds[0].revents & POLLERR)
- <handle error>
-
- /* If no new messages, poll again */
- if (!(pfds[0].revents & POLLIN))
- continue;
-
- /* Process all frames */
- while (1) {
- /* Get next frame header */
- hdr = rx_ring + frame_offset;
-
- if (hdr->nm_status == NL_MMAP_STATUS_VALID) {
- /* Regular memory mapped frame */
- nlh = (void *)hdr + NL_MMAP_HDRLEN;
- len = hdr->nm_len;
-
- /* Release empty message immediately. May happen
- * on error during message construction.
- */
- if (len == 0)
- goto release;
- } else if (hdr->nm_status == NL_MMAP_STATUS_COPY) {
- /* Frame queued to socket receive queue */
- len = recv(fd, buf, sizeof(buf), MSG_DONTWAIT);
- if (len <= 0)
- break;
- nlh = buf;
- } else
- /* No more messages to process, continue polling */
- break;
-
- process_msg(nlh);
-release:
- /* Release frame back to the kernel */
- hdr->nm_status = NL_MMAP_STATUS_UNUSED;
-
- /* Advance frame offset to next frame */
- frame_offset = (frame_offset + frame_size) % ring_size;
- }
- }
-
-Message transmission:
-
-This example assumes some ring parameters of the ring setup are available.
-A single message is constructed and transmitted, to send multiple messages
-at once they would be constructed in consecutive frames before a final call
-to sendto().
-
- unsigned int frame_offset = 0;
- struct nl_mmap_hdr *hdr;
- struct nlmsghdr *nlh;
- struct sockaddr_nl addr = {
- .nl_family = AF_NETLINK,
- };
-
- hdr = tx_ring + frame_offset;
- if (hdr->nm_status != NL_MMAP_STATUS_UNUSED)
- /* No frame available. Use poll() to avoid. */
- exit(1);
-
- nlh = (void *)hdr + NL_MMAP_HDRLEN;
-
- /* Build message */
- build_message(nlh);
-
- /* Fill frame header: length and status need to be set */
- hdr->nm_len = nlh->nlmsg_len;
- hdr->nm_status = NL_MMAP_STATUS_VALID;
-
- if (sendto(fd, NULL, 0, 0, &addr, sizeof(addr)) < 0)
- exit(1);
-
- /* Advance frame offset to next frame */
- frame_offset = (frame_offset + frame_size) % ring_size;
dev_hold(dev);
- if (netlink_skb_is_mmaped(skb) || is_vmalloc_addr(skb->head))
+ if (is_vmalloc_addr(skb->head))
nskb = netlink_to_full_skb(skb, GFP_ATOMIC);
else
nskb = skb_clone(skb, GFP_ATOMIC);
wake_up_interruptible(&nlk->wait);
}
-#ifdef CONFIG_NETLINK_MMAP
-static bool netlink_rx_is_mmaped(struct sock *sk)
-{
- return nlk_sk(sk)->rx_ring.pg_vec != NULL;
-}
-
-static bool netlink_tx_is_mmaped(struct sock *sk)
-{
- return nlk_sk(sk)->tx_ring.pg_vec != NULL;
-}
-
-static __pure struct page *pgvec_to_page(const void *addr)
-{
- if (is_vmalloc_addr(addr))
- return vmalloc_to_page(addr);
- else
- return virt_to_page(addr);
-}
-
-static void free_pg_vec(void **pg_vec, unsigned int order, unsigned int len)
-{
- unsigned int i;
-
- for (i = 0; i < len; i++) {
- if (pg_vec[i] != NULL) {
- if (is_vmalloc_addr(pg_vec[i]))
- vfree(pg_vec[i]);
- else
- free_pages((unsigned long)pg_vec[i], order);
- }
- }
- kfree(pg_vec);
-}
-
-static void *alloc_one_pg_vec_page(unsigned long order)
-{
- void *buffer;
- gfp_t gfp_flags = GFP_KERNEL | __GFP_COMP | __GFP_ZERO |
- __GFP_NOWARN | __GFP_NORETRY;
-
- buffer = (void *)__get_free_pages(gfp_flags, order);
- if (buffer != NULL)
- return buffer;
-
- buffer = vzalloc((1 << order) * PAGE_SIZE);
- if (buffer != NULL)
- return buffer;
-
- gfp_flags &= ~__GFP_NORETRY;
- return (void *)__get_free_pages(gfp_flags, order);
-}
-
-static void **alloc_pg_vec(struct netlink_sock *nlk,
- struct nl_mmap_req *req, unsigned int order)
-{
- unsigned int block_nr = req->nm_block_nr;
- unsigned int i;
- void **pg_vec;
-
- pg_vec = kcalloc(block_nr, sizeof(void *), GFP_KERNEL);
- if (pg_vec == NULL)
- return NULL;
-
- for (i = 0; i < block_nr; i++) {
- pg_vec[i] = alloc_one_pg_vec_page(order);
- if (pg_vec[i] == NULL)
- goto err1;
- }
-
- return pg_vec;
-err1:
- free_pg_vec(pg_vec, order, block_nr);
- return NULL;
-}
-
-
-static void
-__netlink_set_ring(struct sock *sk, struct nl_mmap_req *req, bool tx_ring, void **pg_vec,
- unsigned int order)
-{
- struct netlink_sock *nlk = nlk_sk(sk);
- struct sk_buff_head *queue;
- struct netlink_ring *ring;
-
- queue = tx_ring ? &sk->sk_write_queue : &sk->sk_receive_queue;
- ring = tx_ring ? &nlk->tx_ring : &nlk->rx_ring;
-
- spin_lock_bh(&queue->lock);
-
- ring->frame_max = req->nm_frame_nr - 1;
- ring->head = 0;
- ring->frame_size = req->nm_frame_size;
- ring->pg_vec_pages = req->nm_block_size / PAGE_SIZE;
-
- swap(ring->pg_vec_len, req->nm_block_nr);
- swap(ring->pg_vec_order, order);
- swap(ring->pg_vec, pg_vec);
-
- __skb_queue_purge(queue);
- spin_unlock_bh(&queue->lock);
-
- WARN_ON(atomic_read(&nlk->mapped));
-
- if (pg_vec)
- free_pg_vec(pg_vec, order, req->nm_block_nr);
-}
-
-static int netlink_set_ring(struct sock *sk, struct nl_mmap_req *req,
- bool tx_ring)
-{
- struct netlink_sock *nlk = nlk_sk(sk);
- struct netlink_ring *ring;
- void **pg_vec = NULL;
- unsigned int order = 0;
-
- ring = tx_ring ? &nlk->tx_ring : &nlk->rx_ring;
-
- if (atomic_read(&nlk->mapped))
- return -EBUSY;
- if (atomic_read(&ring->pending))
- return -EBUSY;
-
- if (req->nm_block_nr) {
- if (ring->pg_vec != NULL)
- return -EBUSY;
-
- if ((int)req->nm_block_size <= 0)
- return -EINVAL;
- if (!PAGE_ALIGNED(req->nm_block_size))
- return -EINVAL;
- if (req->nm_frame_size < NL_MMAP_HDRLEN)
- return -EINVAL;
- if (!IS_ALIGNED(req->nm_frame_size, NL_MMAP_MSG_ALIGNMENT))
- return -EINVAL;
-
- ring->frames_per_block = req->nm_block_size /
- req->nm_frame_size;
- if (ring->frames_per_block == 0)
- return -EINVAL;
- if (ring->frames_per_block * req->nm_block_nr !=
- req->nm_frame_nr)
- return -EINVAL;
-
- order = get_order(req->nm_block_size);
- pg_vec = alloc_pg_vec(nlk, req, order);
- if (pg_vec == NULL)
- return -ENOMEM;
- } else {
- if (req->nm_frame_nr)
- return -EINVAL;
- }
-
- mutex_lock(&nlk->pg_vec_lock);
- if (atomic_read(&nlk->mapped) == 0) {
- __netlink_set_ring(sk, req, tx_ring, pg_vec, order);
- mutex_unlock(&nlk->pg_vec_lock);
- return 0;
- }
-
- mutex_unlock(&nlk->pg_vec_lock);
-
- if (pg_vec)
- free_pg_vec(pg_vec, order, req->nm_block_nr);
-
- return -EBUSY;
-}
-
-static void netlink_mm_open(struct vm_area_struct *vma)
-{
- struct file *file = vma->vm_file;
- struct socket *sock = file->private_data;
- struct sock *sk = sock->sk;
-
- if (sk)
- atomic_inc(&nlk_sk(sk)->mapped);
-}
-
-static void netlink_mm_close(struct vm_area_struct *vma)
-{
- struct file *file = vma->vm_file;
- struct socket *sock = file->private_data;
- struct sock *sk = sock->sk;
-
- if (sk)
- atomic_dec(&nlk_sk(sk)->mapped);
-}
-
-static const struct vm_operations_struct netlink_mmap_ops = {
- .open = netlink_mm_open,
- .close = netlink_mm_close,
-};
-
-static int netlink_mmap(struct file *file, struct socket *sock,
- struct vm_area_struct *vma)
-{
- struct sock *sk = sock->sk;
- struct netlink_sock *nlk = nlk_sk(sk);
- struct netlink_ring *ring;
- unsigned long start, size, expected;
- unsigned int i;
- int err = -EINVAL;
-
- if (vma->vm_pgoff)
- return -EINVAL;
-
- mutex_lock(&nlk->pg_vec_lock);
-
- expected = 0;
- for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
- if (ring->pg_vec == NULL)
- continue;
- expected += ring->pg_vec_len * ring->pg_vec_pages * PAGE_SIZE;
- }
-
- if (expected == 0)
- goto out;
-
- size = vma->vm_end - vma->vm_start;
- if (size != expected)
- goto out;
-
- start = vma->vm_start;
- for (ring = &nlk->rx_ring; ring <= &nlk->tx_ring; ring++) {
- if (ring->pg_vec == NULL)
- continue;
-
- for (i = 0; i < ring->pg_vec_len; i++) {
- struct page *page;
- void *kaddr = ring->pg_vec[i];
- unsigned int pg_num;
-
- for (pg_num = 0; pg_num < ring->pg_vec_pages; pg_num++) {
- page = pgvec_to_page(kaddr);
- err = vm_insert_page(vma, start, page);
- if (err < 0)
- goto out;
- start += PAGE_SIZE;
- kaddr += PAGE_SIZE;
- }
- }
- }
-
- atomic_inc(&nlk->mapped);
- vma->vm_ops = &netlink_mmap_ops;
- err = 0;
-out:
- mutex_unlock(&nlk->pg_vec_lock);
- return err;
-}
-
-static void netlink_frame_flush_dcache(const struct nl_mmap_hdr *hdr, unsigned int nm_len)
-{
-#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_HDRLEN + 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)
-{
- smp_mb();
- hdr->nm_status = status;
- flush_dcache_page(pgvec_to_page(hdr));
-}
-
-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 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;
- const struct nl_mmap_hdr *hdr;
-
- do {
- hdr = __netlink_lookup_frame(ring, ring->head);
- 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 bool netlink_has_valid_frame(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_VALID)
- return true;
- pos = pos != 0 ? pos - 1 : ring->frame_max;
- } while (pos != head);
-
- return false;
-}
-
-static bool netlink_dump_space(struct netlink_sock *nlk)
-{
- struct netlink_ring *ring = &nlk->rx_ring;
- struct nl_mmap_hdr *hdr;
- unsigned int n;
-
- hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
- if (hdr == NULL)
- return false;
-
- n = ring->head + ring->frame_max / 2;
- if (n > ring->frame_max)
- n -= ring->frame_max;
-
- hdr = __netlink_lookup_frame(ring, n);
-
- return hdr->nm_status == NL_MMAP_STATUS_UNUSED;
-}
-
-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;
- int err;
-
- if (nlk->rx_ring.pg_vec != NULL) {
- /* Memory mapped sockets don't call recvmsg(), so flow control
- * for dumps is performed here. A dump is allowed to continue
- * if at least half the ring is unused.
- */
- while (nlk->cb_running && netlink_dump_space(nlk)) {
- err = netlink_dump(sk);
- if (err < 0) {
- sk->sk_err = -err;
- sk->sk_error_report(sk);
- break;
- }
- }
- netlink_rcv_wake(sk);
- }
-
- mask = datagram_poll(file, sock, wait);
-
- /* We could already have received frames in the normal receive
- * queue, that will show up as NL_MMAP_STATUS_COPY in the ring,
- * so if mask contains pollin/etc already, there's no point
- * walking the ring.
- */
- if ((mask & (POLLIN | POLLRDNORM)) != (POLLIN | POLLRDNORM)) {
- spin_lock_bh(&sk->sk_receive_queue.lock);
- if (nlk->rx_ring.pg_vec) {
- if (netlink_has_valid_frame(&nlk->rx_ring))
- 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;
-}
-
-static int netlink_mmap_sendmsg(struct sock *sk, struct msghdr *msg,
- u32 dst_portid, u32 dst_group,
- struct scm_cookie *scm)
-{
- struct netlink_sock *nlk = nlk_sk(sk);
- struct netlink_ring *ring;
- struct nl_mmap_hdr *hdr;
- struct sk_buff *skb;
- unsigned int maxlen;
- int err = 0, len = 0;
-
- mutex_lock(&nlk->pg_vec_lock);
-
- ring = &nlk->tx_ring;
- maxlen = ring->frame_size - NL_MMAP_HDRLEN;
-
- do {
- unsigned int nm_len;
-
- hdr = netlink_current_frame(ring, NL_MMAP_STATUS_VALID);
- if (hdr == NULL) {
- if (!(msg->msg_flags & MSG_DONTWAIT) &&
- atomic_read(&nlk->tx_ring.pending))
- schedule();
- continue;
- }
-
- nm_len = ACCESS_ONCE(hdr->nm_len);
- if (nm_len > maxlen) {
- err = -EINVAL;
- goto out;
- }
-
- netlink_frame_flush_dcache(hdr, nm_len);
-
- skb = alloc_skb(nm_len, GFP_KERNEL);
- if (skb == NULL) {
- err = -ENOBUFS;
- goto out;
- }
- __skb_put(skb, nm_len);
- memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, nm_len);
- netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
-
- netlink_increment_head(ring);
-
- NETLINK_CB(skb).portid = nlk->portid;
- NETLINK_CB(skb).dst_group = dst_group;
- NETLINK_CB(skb).creds = scm->creds;
-
- err = security_netlink_send(sk, skb);
- if (err) {
- kfree_skb(skb);
- goto out;
- }
-
- if (unlikely(dst_group)) {
- atomic_inc(&skb->users);
- netlink_broadcast(sk, skb, dst_portid, dst_group,
- GFP_KERNEL);
- }
- err = netlink_unicast(sk, skb, dst_portid,
- msg->msg_flags & MSG_DONTWAIT);
- if (err < 0)
- goto out;
- len += err;
-
- } while (hdr != NULL ||
- (!(msg->msg_flags & MSG_DONTWAIT) &&
- atomic_read(&nlk->tx_ring.pending)));
-
- if (len > 0)
- err = len;
-out:
- mutex_unlock(&nlk->pg_vec_lock);
- return err;
-}
-
-static void netlink_queue_mmaped_skb(struct sock *sk, struct sk_buff *skb)
-{
- struct nl_mmap_hdr *hdr;
-
- hdr = netlink_mmap_hdr(skb);
- hdr->nm_len = skb->len;
- hdr->nm_group = NETLINK_CB(skb).dst_group;
- hdr->nm_pid = NETLINK_CB(skb).creds.pid;
- hdr->nm_uid = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
- hdr->nm_gid = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
- netlink_frame_flush_dcache(hdr, hdr->nm_len);
- netlink_set_status(hdr, NL_MMAP_STATUS_VALID);
-
- NETLINK_CB(skb).flags |= NETLINK_SKB_DELIVERED;
- kfree_skb(skb);
-}
-
-static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
-{
- struct netlink_sock *nlk = nlk_sk(sk);
- struct netlink_ring *ring = &nlk->rx_ring;
- struct nl_mmap_hdr *hdr;
-
- spin_lock_bh(&sk->sk_receive_queue.lock);
- hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
- if (hdr == NULL) {
- spin_unlock_bh(&sk->sk_receive_queue.lock);
- kfree_skb(skb);
- netlink_overrun(sk);
- return;
- }
- netlink_increment_head(ring);
- __skb_queue_tail(&sk->sk_receive_queue, skb);
- spin_unlock_bh(&sk->sk_receive_queue.lock);
-
- hdr->nm_len = skb->len;
- hdr->nm_group = NETLINK_CB(skb).dst_group;
- hdr->nm_pid = NETLINK_CB(skb).creds.pid;
- hdr->nm_uid = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
- hdr->nm_gid = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
- netlink_set_status(hdr, NL_MMAP_STATUS_COPY);
-}
-
-#else /* CONFIG_NETLINK_MMAP */
-#define netlink_rx_is_mmaped(sk) false
-#define netlink_tx_is_mmaped(sk) false
-#define netlink_mmap sock_no_mmap
-#define netlink_poll datagram_poll
-#define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, scm) 0
-#endif /* CONFIG_NETLINK_MMAP */
-
static void netlink_skb_destructor(struct sk_buff *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_TX) {
- netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
- ring = &nlk_sk(sk)->tx_ring;
- } else {
- 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->head = NULL;
- }
-#endif
if (is_vmalloc_addr(skb->head)) {
if (!skb->cloned ||
!atomic_dec_return(&(skb_shinfo(skb)->dataref)))
}
skb_queue_purge(&sk->sk_receive_queue);
-#ifdef CONFIG_NETLINK_MMAP
- if (1) {
- struct nl_mmap_req req;
-
- memset(&req, 0, sizeof(req));
- if (nlk->rx_ring.pg_vec)
- __netlink_set_ring(sk, &req, false, NULL, 0);
- memset(&req, 0, sizeof(req));
- if (nlk->tx_ring.pg_vec)
- __netlink_set_ring(sk, &req, true, NULL, 0);
- }
-#endif /* CONFIG_NETLINK_MMAP */
if (!sock_flag(sk, SOCK_DEAD)) {
printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
mutex_init(nlk->cb_mutex);
}
init_waitqueue_head(&nlk->wait);
-#ifdef CONFIG_NETLINK_MMAP
- mutex_init(&nlk->pg_vec_lock);
-#endif
sk->sk_destruct = netlink_sock_destruct;
sk->sk_protocol = protocol;
nlk = nlk_sk(sk);
if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
- test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
- !netlink_skb_is_mmaped(skb)) {
+ test_bit(NETLINK_S_CONGESTED, &nlk->state))) {
DECLARE_WAITQUEUE(wait, current);
if (!*timeo) {
if (!ssk || netlink_is_kernel(ssk))
netlink_deliver_tap(skb);
-#ifdef CONFIG_NETLINK_MMAP
- if (netlink_skb_is_mmaped(skb))
- netlink_queue_mmaped_skb(sk, skb);
- else if (netlink_rx_is_mmaped(sk))
- netlink_ring_set_copied(sk, skb);
- else
-#endif /* CONFIG_NETLINK_MMAP */
- skb_queue_tail(&sk->sk_receive_queue, skb);
+ skb_queue_tail(&sk->sk_receive_queue, skb);
sk->sk_data_ready(sk);
return len;
}
int delta;
WARN_ON(skb->sk != NULL);
- if (netlink_skb_is_mmaped(skb))
- return skb;
-
delta = skb->end - skb->tail;
if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
return skb;
unsigned int ldiff, u32 dst_portid,
gfp_t gfp_mask)
{
-#ifdef CONFIG_NETLINK_MMAP
- unsigned int maxlen, linear_size;
- struct sock *sk = NULL;
- struct sk_buff *skb;
- struct netlink_ring *ring;
- struct nl_mmap_hdr *hdr;
-
- sk = netlink_getsockbyportid(ssk, dst_portid);
- if (IS_ERR(sk))
- goto out;
-
- ring = &nlk_sk(sk)->rx_ring;
- /* fast-path without atomic ops for common case: non-mmaped receiver */
- if (ring->pg_vec == NULL)
- goto out_put;
-
- /* We need to account the full linear size needed as a ring
- * slot cannot have non-linear parts.
- */
- linear_size = size + ldiff;
- if (ring->frame_size - NL_MMAP_HDRLEN < linear_size)
- goto out_put;
-
- skb = alloc_skb_head(gfp_mask);
- if (skb == NULL)
- goto err1;
-
- spin_lock_bh(&sk->sk_receive_queue.lock);
- /* check again under lock */
- if (ring->pg_vec == NULL)
- goto out_free;
-
- /* check again under lock */
- maxlen = ring->frame_size - NL_MMAP_HDRLEN;
- if (maxlen < linear_size)
- goto out_free;
-
- netlink_forward_ring(ring);
- hdr = netlink_current_frame(ring, NL_MMAP_STATUS_UNUSED);
- if (hdr == NULL)
- goto err2;
-
- netlink_ring_setup_skb(skb, sk, ring, hdr);
- netlink_set_status(hdr, NL_MMAP_STATUS_RESERVED);
- atomic_inc(&ring->pending);
- netlink_increment_head(ring);
-
- spin_unlock_bh(&sk->sk_receive_queue.lock);
- return skb;
-
-err2:
- kfree_skb(skb);
- spin_unlock_bh(&sk->sk_receive_queue.lock);
- netlink_overrun(sk);
-err1:
- sock_put(sk);
- return NULL;
-
-out_free:
- kfree_skb(skb);
- spin_unlock_bh(&sk->sk_receive_queue.lock);
-out_put:
- sock_put(sk);
-out:
-#endif
return alloc_skb(size, gfp_mask);
}
EXPORT_SYMBOL_GPL(__netlink_alloc_skb);
if (level != SOL_NETLINK)
return -ENOPROTOOPT;
- if (optname != NETLINK_RX_RING && optname != NETLINK_TX_RING &&
- optlen >= sizeof(int) &&
+ if (optlen >= sizeof(int) &&
get_user(val, (unsigned int __user *)optval))
return -EFAULT;
}
err = 0;
break;
-#ifdef CONFIG_NETLINK_MMAP
- case NETLINK_RX_RING:
- case NETLINK_TX_RING: {
- struct nl_mmap_req req;
-
- /* Rings might consume more memory than queue limits, require
- * CAP_NET_ADMIN.
- */
- if (!capable(CAP_NET_ADMIN))
- return -EPERM;
- if (optlen < sizeof(req))
- return -EINVAL;
- if (copy_from_user(&req, optval, sizeof(req)))
- return -EFAULT;
- err = netlink_set_ring(sk, &req,
- optname == NETLINK_TX_RING);
- break;
- }
-#endif /* CONFIG_NETLINK_MMAP */
case NETLINK_LISTEN_ALL_NSID:
if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
return -EPERM;
smp_rmb();
}
- /* It's a really convoluted way for userland to ask for mmaped
- * sendmsg(), but that's what we've got...
- */
- if (netlink_tx_is_mmaped(sk) &&
- iter_is_iovec(&msg->msg_iter) &&
- msg->msg_iter.nr_segs == 1 &&
- msg->msg_iter.iov->iov_base == NULL) {
- err = netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group,
- &scm);
- goto out;
- }
-
err = -EMSGSIZE;
if (len > sk->sk_sndbuf - 32)
goto out;
goto errout_skb;
}
- if (!netlink_rx_is_mmaped(sk) &&
- atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
+ if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
goto errout_skb;
/* NLMSG_GOODSIZE is small to avoid high order allocations being
* reasonable static buffer based on the expected largest dump of a
* single netdev. The outcome is MSG_TRUNC error.
*/
- if (!netlink_rx_is_mmaped(sk))
- skb_reserve(skb, skb_tailroom(skb) - alloc_size);
+ skb_reserve(skb, skb_tailroom(skb) - alloc_size);
netlink_skb_set_owner_r(skb, sk);
len = cb->dump(skb, cb);
struct netlink_sock *nlk;
int ret;
- /* Memory mapped dump requests need to be copied to avoid looping
- * on the pending state in netlink_mmap_sendmsg() while the CB hold
- * a reference to the skb.
- */
- if (netlink_skb_is_mmaped(skb)) {
- skb = skb_copy(skb, GFP_KERNEL);
- if (skb == NULL)
- return -ENOBUFS;
- } else
- atomic_inc(&skb->users);
+ atomic_inc(&skb->users);
sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
if (sk == NULL) {
.socketpair = sock_no_socketpair,
.accept = sock_no_accept,
.getname = netlink_getname,
- .poll = netlink_poll,
+ .poll = datagram_poll,
.ioctl = sock_no_ioctl,
.listen = sock_no_listen,
.shutdown = sock_no_shutdown,
.getsockopt = netlink_getsockopt,
.sendmsg = netlink_sendmsg,
.recvmsg = netlink_recvmsg,
- .mmap = netlink_mmap,
+ .mmap = sock_no_mmap,
.sendpage = sock_no_sendpage,
};
projects / users / hch / xfs.git / commitdiff