RDS: Message parsing
authorAndy Grover <andy.grover@oracle.com>
Tue, 24 Feb 2009 15:30:26 +0000 (15:30 +0000)
committerDavid S. Miller <davem@davemloft.net>
Fri, 27 Feb 2009 07:39:28 +0000 (23:39 -0800)
Parsing of newly-received RDS message headers (including ext.
headers) and copy-to/from-user routines.

page.c implements a per-cpu page remainder cache, to reduce the
number of allocations needed for small datagrams.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/rds/message.c [new file with mode: 0644]
net/rds/page.c [new file with mode: 0644]

diff --git a/net/rds/message.c b/net/rds/message.c
new file mode 100644 (file)
index 0000000..5a15dc8
--- /dev/null
@@ -0,0 +1,402 @@
+/*
+ * Copyright (c) 2006 Oracle.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+
+#include "rds.h"
+#include "rdma.h"
+
+static DECLARE_WAIT_QUEUE_HEAD(rds_message_flush_waitq);
+
+static unsigned int    rds_exthdr_size[__RDS_EXTHDR_MAX] = {
+[RDS_EXTHDR_NONE]      = 0,
+[RDS_EXTHDR_VERSION]   = sizeof(struct rds_ext_header_version),
+[RDS_EXTHDR_RDMA]      = sizeof(struct rds_ext_header_rdma),
+[RDS_EXTHDR_RDMA_DEST] = sizeof(struct rds_ext_header_rdma_dest),
+};
+
+
+void rds_message_addref(struct rds_message *rm)
+{
+       rdsdebug("addref rm %p ref %d\n", rm, atomic_read(&rm->m_refcount));
+       atomic_inc(&rm->m_refcount);
+}
+
+/*
+ * This relies on dma_map_sg() not touching sg[].page during merging.
+ */
+static void rds_message_purge(struct rds_message *rm)
+{
+       unsigned long i;
+
+       if (unlikely(test_bit(RDS_MSG_PAGEVEC, &rm->m_flags)))
+               return;
+
+       for (i = 0; i < rm->m_nents; i++) {
+               rdsdebug("putting data page %p\n", (void *)sg_page(&rm->m_sg[i]));
+               /* XXX will have to put_page for page refs */
+               __free_page(sg_page(&rm->m_sg[i]));
+       }
+       rm->m_nents = 0;
+
+       if (rm->m_rdma_op)
+               rds_rdma_free_op(rm->m_rdma_op);
+       if (rm->m_rdma_mr)
+               rds_mr_put(rm->m_rdma_mr);
+}
+
+void rds_message_inc_purge(struct rds_incoming *inc)
+{
+       struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
+       rds_message_purge(rm);
+}
+
+void rds_message_put(struct rds_message *rm)
+{
+       rdsdebug("put rm %p ref %d\n", rm, atomic_read(&rm->m_refcount));
+
+       if (atomic_dec_and_test(&rm->m_refcount)) {
+               BUG_ON(!list_empty(&rm->m_sock_item));
+               BUG_ON(!list_empty(&rm->m_conn_item));
+               rds_message_purge(rm);
+
+               kfree(rm);
+       }
+}
+
+void rds_message_inc_free(struct rds_incoming *inc)
+{
+       struct rds_message *rm = container_of(inc, struct rds_message, m_inc);
+       rds_message_put(rm);
+}
+
+void rds_message_populate_header(struct rds_header *hdr, __be16 sport,
+                                __be16 dport, u64 seq)
+{
+       hdr->h_flags = 0;
+       hdr->h_sport = sport;
+       hdr->h_dport = dport;
+       hdr->h_sequence = cpu_to_be64(seq);
+       hdr->h_exthdr[0] = RDS_EXTHDR_NONE;
+}
+
+int rds_message_add_extension(struct rds_header *hdr,
+               unsigned int type, const void *data, unsigned int len)
+{
+       unsigned int ext_len = sizeof(u8) + len;
+       unsigned char *dst;
+
+       /* For now, refuse to add more than one extension header */
+       if (hdr->h_exthdr[0] != RDS_EXTHDR_NONE)
+               return 0;
+
+       if (type >= __RDS_EXTHDR_MAX
+        || len != rds_exthdr_size[type])
+               return 0;
+
+       if (ext_len >= RDS_HEADER_EXT_SPACE)
+               return 0;
+       dst = hdr->h_exthdr;
+
+       *dst++ = type;
+       memcpy(dst, data, len);
+
+       dst[len] = RDS_EXTHDR_NONE;
+       return 1;
+}
+
+/*
+ * If a message has extension headers, retrieve them here.
+ * Call like this:
+ *
+ * unsigned int pos = 0;
+ *
+ * while (1) {
+ *     buflen = sizeof(buffer);
+ *     type = rds_message_next_extension(hdr, &pos, buffer, &buflen);
+ *     if (type == RDS_EXTHDR_NONE)
+ *             break;
+ *     ...
+ * }
+ */
+int rds_message_next_extension(struct rds_header *hdr,
+               unsigned int *pos, void *buf, unsigned int *buflen)
+{
+       unsigned int offset, ext_type, ext_len;
+       u8 *src = hdr->h_exthdr;
+
+       offset = *pos;
+       if (offset >= RDS_HEADER_EXT_SPACE)
+               goto none;
+
+       /* Get the extension type and length. For now, the
+        * length is implied by the extension type. */
+       ext_type = src[offset++];
+
+       if (ext_type == RDS_EXTHDR_NONE || ext_type >= __RDS_EXTHDR_MAX)
+               goto none;
+       ext_len = rds_exthdr_size[ext_type];
+       if (offset + ext_len > RDS_HEADER_EXT_SPACE)
+               goto none;
+
+       *pos = offset + ext_len;
+       if (ext_len < *buflen)
+               *buflen = ext_len;
+       memcpy(buf, src + offset, *buflen);
+       return ext_type;
+
+none:
+       *pos = RDS_HEADER_EXT_SPACE;
+       *buflen = 0;
+       return RDS_EXTHDR_NONE;
+}
+
+int rds_message_add_version_extension(struct rds_header *hdr, unsigned int version)
+{
+       struct rds_ext_header_version ext_hdr;
+
+       ext_hdr.h_version = cpu_to_be32(version);
+       return rds_message_add_extension(hdr, RDS_EXTHDR_VERSION, &ext_hdr, sizeof(ext_hdr));
+}
+
+int rds_message_get_version_extension(struct rds_header *hdr, unsigned int *version)
+{
+       struct rds_ext_header_version ext_hdr;
+       unsigned int pos = 0, len = sizeof(ext_hdr);
+
+       /* We assume the version extension is the only one present */
+       if (rds_message_next_extension(hdr, &pos, &ext_hdr, &len) != RDS_EXTHDR_VERSION)
+               return 0;
+       *version = be32_to_cpu(ext_hdr.h_version);
+       return 1;
+}
+
+int rds_message_add_rdma_dest_extension(struct rds_header *hdr, u32 r_key, u32 offset)
+{
+       struct rds_ext_header_rdma_dest ext_hdr;
+
+       ext_hdr.h_rdma_rkey = cpu_to_be32(r_key);
+       ext_hdr.h_rdma_offset = cpu_to_be32(offset);
+       return rds_message_add_extension(hdr, RDS_EXTHDR_RDMA_DEST, &ext_hdr, sizeof(ext_hdr));
+}
+
+struct rds_message *rds_message_alloc(unsigned int nents, gfp_t gfp)
+{
+       struct rds_message *rm;
+
+       rm = kzalloc(sizeof(struct rds_message) +
+                    (nents * sizeof(struct scatterlist)), gfp);
+       if (!rm)
+               goto out;
+
+       if (nents)
+               sg_init_table(rm->m_sg, nents);
+       atomic_set(&rm->m_refcount, 1);
+       INIT_LIST_HEAD(&rm->m_sock_item);
+       INIT_LIST_HEAD(&rm->m_conn_item);
+       spin_lock_init(&rm->m_rs_lock);
+
+out:
+       return rm;
+}
+
+struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned int total_len)
+{
+       struct rds_message *rm;
+       unsigned int i;
+
+       rm = rds_message_alloc(ceil(total_len, PAGE_SIZE), GFP_KERNEL);
+       if (rm == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       set_bit(RDS_MSG_PAGEVEC, &rm->m_flags);
+       rm->m_inc.i_hdr.h_len = cpu_to_be32(total_len);
+       rm->m_nents = ceil(total_len, PAGE_SIZE);
+
+       for (i = 0; i < rm->m_nents; ++i) {
+               sg_set_page(&rm->m_sg[i],
+                               virt_to_page(page_addrs[i]),
+                               PAGE_SIZE, 0);
+       }
+
+       return rm;
+}
+
+struct rds_message *rds_message_copy_from_user(struct iovec *first_iov,
+                                              size_t total_len)
+{
+       unsigned long to_copy;
+       unsigned long iov_off;
+       unsigned long sg_off;
+       struct rds_message *rm;
+       struct iovec *iov;
+       struct scatterlist *sg;
+       int ret;
+
+       rm = rds_message_alloc(ceil(total_len, PAGE_SIZE), GFP_KERNEL);
+       if (rm == NULL) {
+               ret = -ENOMEM;
+               goto out;
+       }
+
+       rm->m_inc.i_hdr.h_len = cpu_to_be32(total_len);
+
+       /*
+        * now allocate and copy in the data payload.
+        */
+       sg = rm->m_sg;
+       iov = first_iov;
+       iov_off = 0;
+       sg_off = 0; /* Dear gcc, sg->page will be null from kzalloc. */
+
+       while (total_len) {
+               if (sg_page(sg) == NULL) {
+                       ret = rds_page_remainder_alloc(sg, total_len,
+                                                      GFP_HIGHUSER);
+                       if (ret)
+                               goto out;
+                       rm->m_nents++;
+                       sg_off = 0;
+               }
+
+               while (iov_off == iov->iov_len) {
+                       iov_off = 0;
+                       iov++;
+               }
+
+               to_copy = min(iov->iov_len - iov_off, sg->length - sg_off);
+               to_copy = min_t(size_t, to_copy, total_len);
+
+               rdsdebug("copying %lu bytes from user iov [%p, %zu] + %lu to "
+                        "sg [%p, %u, %u] + %lu\n",
+                        to_copy, iov->iov_base, iov->iov_len, iov_off,
+                        (void *)sg_page(sg), sg->offset, sg->length, sg_off);
+
+               ret = rds_page_copy_from_user(sg_page(sg), sg->offset + sg_off,
+                                             iov->iov_base + iov_off,
+                                             to_copy);
+               if (ret)
+                       goto out;
+
+               iov_off += to_copy;
+               total_len -= to_copy;
+               sg_off += to_copy;
+
+               if (sg_off == sg->length)
+                       sg++;
+       }
+
+       ret = 0;
+out:
+       if (ret) {
+               if (rm)
+                       rds_message_put(rm);
+               rm = ERR_PTR(ret);
+       }
+       return rm;
+}
+
+int rds_message_inc_copy_to_user(struct rds_incoming *inc,
+                                struct iovec *first_iov, size_t size)
+{
+       struct rds_message *rm;
+       struct iovec *iov;
+       struct scatterlist *sg;
+       unsigned long to_copy;
+       unsigned long iov_off;
+       unsigned long vec_off;
+       int copied;
+       int ret;
+       u32 len;
+
+       rm = container_of(inc, struct rds_message, m_inc);
+       len = be32_to_cpu(rm->m_inc.i_hdr.h_len);
+
+       iov = first_iov;
+       iov_off = 0;
+       sg = rm->m_sg;
+       vec_off = 0;
+       copied = 0;
+
+       while (copied < size && copied < len) {
+               while (iov_off == iov->iov_len) {
+                       iov_off = 0;
+                       iov++;
+               }
+
+               to_copy = min(iov->iov_len - iov_off, sg->length - vec_off);
+               to_copy = min_t(size_t, to_copy, size - copied);
+               to_copy = min_t(unsigned long, to_copy, len - copied);
+
+               rdsdebug("copying %lu bytes to user iov [%p, %zu] + %lu to "
+                        "sg [%p, %u, %u] + %lu\n",
+                        to_copy, iov->iov_base, iov->iov_len, iov_off,
+                        sg_page(sg), sg->offset, sg->length, vec_off);
+
+               ret = rds_page_copy_to_user(sg_page(sg), sg->offset + vec_off,
+                                           iov->iov_base + iov_off,
+                                           to_copy);
+               if (ret) {
+                       copied = ret;
+                       break;
+               }
+
+               iov_off += to_copy;
+               vec_off += to_copy;
+               copied += to_copy;
+
+               if (vec_off == sg->length) {
+                       vec_off = 0;
+                       sg++;
+               }
+       }
+
+       return copied;
+}
+
+/*
+ * If the message is still on the send queue, wait until the transport
+ * is done with it. This is particularly important for RDMA operations.
+ */
+void rds_message_wait(struct rds_message *rm)
+{
+       wait_event(rds_message_flush_waitq,
+                       !test_bit(RDS_MSG_MAPPED, &rm->m_flags));
+}
+
+void rds_message_unmapped(struct rds_message *rm)
+{
+       clear_bit(RDS_MSG_MAPPED, &rm->m_flags);
+       if (waitqueue_active(&rds_message_flush_waitq))
+               wake_up(&rds_message_flush_waitq);
+}
+
diff --git a/net/rds/page.c b/net/rds/page.c
new file mode 100644 (file)
index 0000000..c460743
--- /dev/null
@@ -0,0 +1,221 @@
+/*
+ * Copyright (c) 2006 Oracle.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/highmem.h>
+
+#include "rds.h"
+
+struct rds_page_remainder {
+       struct page     *r_page;
+       unsigned long   r_offset;
+};
+
+DEFINE_PER_CPU(struct rds_page_remainder, rds_page_remainders) ____cacheline_aligned;
+
+/*
+ * returns 0 on success or -errno on failure.
+ *
+ * We don't have to worry about flush_dcache_page() as this only works
+ * with private pages.  If, say, we were to do directed receive to pinned
+ * user pages we'd have to worry more about cache coherence.  (Though
+ * the flush_dcache_page() in get_user_pages() would probably be enough).
+ */
+int rds_page_copy_user(struct page *page, unsigned long offset,
+                      void __user *ptr, unsigned long bytes,
+                      int to_user)
+{
+       unsigned long ret;
+       void *addr;
+
+       if (to_user)
+               rds_stats_add(s_copy_to_user, bytes);
+       else
+               rds_stats_add(s_copy_from_user, bytes);
+
+       addr = kmap_atomic(page, KM_USER0);
+       if (to_user)
+               ret = __copy_to_user_inatomic(ptr, addr + offset, bytes);
+       else
+               ret = __copy_from_user_inatomic(addr + offset, ptr, bytes);
+       kunmap_atomic(addr, KM_USER0);
+
+       if (ret) {
+               addr = kmap(page);
+               if (to_user)
+                       ret = copy_to_user(ptr, addr + offset, bytes);
+               else
+                       ret = copy_from_user(addr + offset, ptr, bytes);
+               kunmap(page);
+               if (ret)
+                       return -EFAULT;
+       }
+
+       return 0;
+}
+
+/*
+ * Message allocation uses this to build up regions of a message.
+ *
+ * @bytes - the number of bytes needed.
+ * @gfp - the waiting behaviour of the allocation
+ *
+ * @gfp is always ored with __GFP_HIGHMEM.  Callers must be prepared to
+ * kmap the pages, etc.
+ *
+ * If @bytes is at least a full page then this just returns a page from
+ * alloc_page().
+ *
+ * If @bytes is a partial page then this stores the unused region of the
+ * page in a per-cpu structure.  Future partial-page allocations may be
+ * satisfied from that cached region.  This lets us waste less memory on
+ * small allocations with minimal complexity.  It works because the transmit
+ * path passes read-only page regions down to devices.  They hold a page
+ * reference until they are done with the region.
+ */
+int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
+                            gfp_t gfp)
+{
+       struct rds_page_remainder *rem;
+       unsigned long flags;
+       struct page *page;
+       int ret;
+
+       gfp |= __GFP_HIGHMEM;
+
+       /* jump straight to allocation if we're trying for a huge page */
+       if (bytes >= PAGE_SIZE) {
+               page = alloc_page(gfp);
+               if (page == NULL) {
+                       ret = -ENOMEM;
+               } else {
+                       sg_set_page(scat, page, PAGE_SIZE, 0);
+                       ret = 0;
+               }
+               goto out;
+       }
+
+       rem = &per_cpu(rds_page_remainders, get_cpu());
+       local_irq_save(flags);
+
+       while (1) {
+               /* avoid a tiny region getting stuck by tossing it */
+               if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
+                       rds_stats_inc(s_page_remainder_miss);
+                       __free_page(rem->r_page);
+                       rem->r_page = NULL;
+               }
+
+               /* hand out a fragment from the cached page */
+               if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
+                       sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
+                       get_page(sg_page(scat));
+
+                       if (rem->r_offset != 0)
+                               rds_stats_inc(s_page_remainder_hit);
+
+                       rem->r_offset += bytes;
+                       if (rem->r_offset == PAGE_SIZE) {
+                               __free_page(rem->r_page);
+                               rem->r_page = NULL;
+                       }
+                       ret = 0;
+                       break;
+               }
+
+               /* alloc if there is nothing for us to use */
+               local_irq_restore(flags);
+               put_cpu();
+
+               page = alloc_page(gfp);
+
+               rem = &per_cpu(rds_page_remainders, get_cpu());
+               local_irq_save(flags);
+
+               if (page == NULL) {
+                       ret = -ENOMEM;
+                       break;
+               }
+
+               /* did someone race to fill the remainder before us? */
+               if (rem->r_page) {
+                       __free_page(page);
+                       continue;
+               }
+
+               /* otherwise install our page and loop around to alloc */
+               rem->r_page = page;
+               rem->r_offset = 0;
+       }
+
+       local_irq_restore(flags);
+       put_cpu();
+out:
+       rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
+                ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
+                ret ? 0 : scat->length);
+       return ret;
+}
+
+static int rds_page_remainder_cpu_notify(struct notifier_block *self,
+                                        unsigned long action, void *hcpu)
+{
+       struct rds_page_remainder *rem;
+       long cpu = (long)hcpu;
+
+       rem = &per_cpu(rds_page_remainders, cpu);
+
+       rdsdebug("cpu %ld action 0x%lx\n", cpu, action);
+
+       switch (action) {
+       case CPU_DEAD:
+               if (rem->r_page)
+                       __free_page(rem->r_page);
+               rem->r_page = NULL;
+               break;
+       }
+
+       return 0;
+}
+
+static struct notifier_block rds_page_remainder_nb = {
+       .notifier_call = rds_page_remainder_cpu_notify,
+};
+
+void rds_page_exit(void)
+{
+       int i;
+
+       for_each_possible_cpu(i)
+               rds_page_remainder_cpu_notify(&rds_page_remainder_nb,
+                                             (unsigned long)CPU_DEAD,
+                                             (void *)(long)i);
+}