RDS: Info and stats

RDS currently generates a lot of stats that are accessible via
the rds-info utility. This code implements the support for this.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 419 insertions, 0 deletions

diff --git a/net/rds/info.c b/net/rds/info.c
new file mode 100644
index 000000000000..1d885535214d
--- /dev/null
+++ b/net/rds/info.c
@@ -0,0 +1,241 @@
+/*
+ * 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/percpu.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+
+#include "rds.h"
+
+/*
+ * This file implements a getsockopt() call which copies a set of fixed
+ * sized structs into a user-specified buffer as a means of providing
+ * read-only information about RDS.
+ *
+ * For a given information source there are a given number of fixed sized
+ * structs at a given time.  The structs are only copied if the user-specified
+ * buffer is big enough.  The destination pages that make up the buffer
+ * are pinned for the duration of the copy.
+ *
+ * This gives us the following benefits:
+ *
+ * - simple implementation, no copy "position" across multiple calls
+ * - consistent snapshot of an info source
+ * - atomic copy works well with whatever locking info source has
+ * - one portable tool to get rds info across implementations
+ * - long-lived tool can get info without allocating
+ *
+ * at the following costs:
+ *
+ * - info source copy must be pinned, may be "large"
+ */
+
+struct rds_info_iterator {
+        struct page **pages;
+        void *addr;
+        unsigned long offset;
+};
+
+static DEFINE_SPINLOCK(rds_info_lock);
+static rds_info_func rds_info_funcs[RDS_INFO_LAST - RDS_INFO_FIRST + 1];
+
+void rds_info_register_func(int optname, rds_info_func func)
+{
+        int offset = optname - RDS_INFO_FIRST;
+
+        BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST);
+
+        spin_lock(&rds_info_lock);
+        BUG_ON(rds_info_funcs[offset] != NULL);
+        rds_info_funcs[offset] = func;
+        spin_unlock(&rds_info_lock);
+}
+
+void rds_info_deregister_func(int optname, rds_info_func func)
+{
+        int offset = optname - RDS_INFO_FIRST;
+
+        BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST);
+
+        spin_lock(&rds_info_lock);
+        BUG_ON(rds_info_funcs[offset] != func);
+        rds_info_funcs[offset] = NULL;
+        spin_unlock(&rds_info_lock);
+}
+
+/*
+ * Typically we hold an atomic kmap across multiple rds_info_copy() calls
+ * because the kmap is so expensive.  This must be called before using blocking
+ * operations while holding the mapping and as the iterator is torn down.
+ */
+void rds_info_iter_unmap(struct rds_info_iterator *iter)
+{
+        if (iter->addr != NULL) {
+                kunmap_atomic(iter->addr, KM_USER0);
+                iter->addr = NULL;
+        }
+}
+
+/*
+ * get_user_pages() called flush_dcache_page() on the pages for us.
+ */
+void rds_info_copy(struct rds_info_iterator *iter, void *data,
+                   unsigned long bytes)
+{
+        unsigned long this;
+
+        while (bytes) {
+                if (iter->addr == NULL)
+                        iter->addr = kmap_atomic(*iter->pages, KM_USER0);
+
+                this = min(bytes, PAGE_SIZE - iter->offset);
+
+                rdsdebug("page %p addr %p offset %lu this %lu data %p "
+                          "bytes %lu\n", *iter->pages, iter->addr,
+                          iter->offset, this, data, bytes);
+
+                memcpy(iter->addr + iter->offset, data, this);
+
+                data += this;
+                bytes -= this;
+                iter->offset += this;
+
+                if (iter->offset == PAGE_SIZE) {
+                        kunmap_atomic(iter->addr, KM_USER0);
+                        iter->addr = NULL;
+                        iter->offset = 0;
+                        iter->pages++;
+                }
+        }
+}
+
+/*
+ * @optval points to the userspace buffer that the information snapshot
+ * will be copied into.
+ *
+ * @optlen on input is the size of the buffer in userspace.  @optlen
+ * on output is the size of the requested snapshot in bytes.
+ *
+ * This function returns -errno if there is a failure, particularly -ENOSPC
+ * if the given userspace buffer was not large enough to fit the snapshot.
+ * On success it returns the positive number of bytes of each array element
+ * in the snapshot.
+ */
+int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval,
+                        int __user *optlen)
+{
+        struct rds_info_iterator iter;
+        struct rds_info_lengths lens;
+        unsigned long nr_pages = 0;
+        unsigned long start;
+        unsigned long i;
+        rds_info_func func;
+        struct page **pages = NULL;
+        int ret;
+        int len;
+        int total;
+
+        if (get_user(len, optlen)) {
+                ret = -EFAULT;
+                goto out;
+        }
+
+        /* check for all kinds of wrapping and the like */
+        start = (unsigned long)optval;
+        if (len < 0 || len + PAGE_SIZE - 1 < len || start + len < start) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        /* a 0 len call is just trying to probe its length */
+        if (len == 0)
+                goto call_func;
+
+        nr_pages = (PAGE_ALIGN(start + len) - (start & PAGE_MASK))
+                        >> PAGE_SHIFT;
+
+        pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
+        if (pages == NULL) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        down_read(&current->mm->mmap_sem);
+        ret = get_user_pages(current, current->mm, start, nr_pages, 1, 0,
+                             pages, NULL);
+        up_read(&current->mm->mmap_sem);
+        if (ret != nr_pages) {
+                if (ret > 0)
+                        nr_pages = ret;
+                else
+                        nr_pages = 0;
+                ret = -EAGAIN; /* XXX ? */
+                goto out;
+        }
+
+        rdsdebug("len %d nr_pages %lu\n", len, nr_pages);
+
+call_func:
+        func = rds_info_funcs[optname - RDS_INFO_FIRST];
+        if (func == NULL) {
+                ret = -ENOPROTOOPT;
+                goto out;
+        }
+
+        iter.pages = pages;
+        iter.addr = NULL;
+        iter.offset = start & (PAGE_SIZE - 1);
+
+        func(sock, len, &iter, &lens);
+        BUG_ON(lens.each == 0);
+
+        total = lens.nr * lens.each;
+
+        rds_info_iter_unmap(&iter);
+
+        if (total > len) {
+                len = total;
+                ret = -ENOSPC;
+        } else {
+                len = total;
+                ret = lens.each;
+        }
+
+        if (put_user(len, optlen))
+                ret = -EFAULT;
+
+out:
+        for (i = 0; pages != NULL && i < nr_pages; i++)
+                put_page(pages[i]);
+        kfree(pages);
+
+        return ret;
+}
diff --git a/net/rds/info.h b/net/rds/info.h
new file mode 100644
index 000000000000..b6c052ca7d22
--- /dev/null
+++ b/net/rds/info.h
@@ -0,0 +1,30 @@
+#ifndef _RDS_INFO_H
+#define _RDS_INFO_H
+
+struct rds_info_lengths {
+        unsigned int    nr;
+        unsigned int    each;
+};
+
+struct rds_info_iterator;
+
+/*
+ * These functions must fill in the fields of @lens to reflect the size
+ * of the available info source.  If the snapshot fits in @len then it
+ * should be copied using @iter.  The caller will deduce if it was copied
+ * or not by comparing the lengths.
+ */
+typedef void (*rds_info_func)(struct socket *sock, unsigned int len,
+                              struct rds_info_iterator *iter,
+                              struct rds_info_lengths *lens);
+
+void rds_info_register_func(int optname, rds_info_func func);
+void rds_info_deregister_func(int optname, rds_info_func func);
+int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval,
+                        int __user *optlen);
+void rds_info_copy(struct rds_info_iterator *iter, void *data,
+                   unsigned long bytes);
+void rds_info_iter_unmap(struct rds_info_iterator *iter);
+
+
+#endif
diff --git a/net/rds/stats.c b/net/rds/stats.c
new file mode 100644
index 000000000000..637146893cf3
--- /dev/null
+++ b/net/rds/stats.c
@@ -0,0 +1,148 @@
+/*
+ * 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/percpu.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+
+#include "rds.h"
+
+DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_statistics, rds_stats);
+
+/* :.,$s/unsigned long\>.*\<s_\(.*\);/"\1",/g */
+
+static char *rds_stat_names[] = {
+        "conn_reset",
+        "recv_drop_bad_checksum",
+        "recv_drop_old_seq",
+        "recv_drop_no_sock",
+        "recv_drop_dead_sock",
+        "recv_deliver_raced",
+        "recv_delivered",
+        "recv_queued",
+        "recv_immediate_retry",
+        "recv_delayed_retry",
+        "recv_ack_required",
+        "recv_rdma_bytes",
+        "recv_ping",
+        "send_queue_empty",
+        "send_queue_full",
+        "send_sem_contention",
+        "send_sem_queue_raced",
+        "send_immediate_retry",
+        "send_delayed_retry",
+        "send_drop_acked",
+        "send_ack_required",
+        "send_queued",
+        "send_rdma",
+        "send_rdma_bytes",
+        "send_pong",
+        "page_remainder_hit",
+        "page_remainder_miss",
+        "copy_to_user",
+        "copy_from_user",
+        "cong_update_queued",
+        "cong_update_received",
+        "cong_send_error",
+        "cong_send_blocked",
+};
+
+void rds_stats_info_copy(struct rds_info_iterator *iter,
+                         uint64_t *values, char **names, size_t nr)
+{
+        struct rds_info_counter ctr;
+        size_t i;
+
+        for (i = 0; i < nr; i++) {
+                BUG_ON(strlen(names[i]) >= sizeof(ctr.name));
+                strncpy(ctr.name, names[i], sizeof(ctr.name) - 1);
+                ctr.value = values[i];
+
+                rds_info_copy(iter, &ctr, sizeof(ctr));
+        }
+}
+
+/*
+ * This gives global counters across all the transports.  The strings
+ * are copied in so that the tool doesn't need knowledge of the specific
+ * stats that we're exporting.  Some are pretty implementation dependent
+ * and may change over time.  That doesn't stop them from being useful.
+ *
+ * This is the only function in the chain that knows about the byte granular
+ * length in userspace.  It converts it to number of stat entries that the
+ * rest of the functions operate in.
+ */
+static void rds_stats_info(struct socket *sock, unsigned int len,
+                           struct rds_info_iterator *iter,
+                           struct rds_info_lengths *lens)
+{
+        struct rds_statistics stats = {0, };
+        uint64_t *src;
+        uint64_t *sum;
+        size_t i;
+        int cpu;
+        unsigned int avail;
+
+        avail = len / sizeof(struct rds_info_counter);
+
+        if (avail < ARRAY_SIZE(rds_stat_names)) {
+                avail = 0;
+                goto trans;
+        }
+
+        for_each_online_cpu(cpu) {
+                src = (uint64_t *)&(per_cpu(rds_stats, cpu));
+                sum = (uint64_t *)&stats;
+                for (i = 0; i < sizeof(stats) / sizeof(uint64_t); i++)
+                        *(sum++) += *(src++);
+        }
+
+        rds_stats_info_copy(iter, (uint64_t *)&stats, rds_stat_names,
+                            ARRAY_SIZE(rds_stat_names));
+        avail -= ARRAY_SIZE(rds_stat_names);
+
+trans:
+        lens->each = sizeof(struct rds_info_counter);
+        lens->nr = rds_trans_stats_info_copy(iter, avail) +
+                   ARRAY_SIZE(rds_stat_names);
+}
+
+void rds_stats_exit(void)
+{
+        rds_info_deregister_func(RDS_INFO_COUNTERS, rds_stats_info);
+}
+
+int __init rds_stats_init(void)
+{
+        rds_info_register_func(RDS_INFO_COUNTERS, rds_stats_info);
+        return 0;
+}