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-rw-r--r--fs/relayfs/relay.c431
1 files changed, 431 insertions, 0 deletions
diff --git a/fs/relayfs/relay.c b/fs/relayfs/relay.c
new file mode 100644
index 00000000000..16446a15c96
--- /dev/null
+++ b/fs/relayfs/relay.c
@@ -0,0 +1,431 @@
+/*
+ * Public API and common code for RelayFS.
+ *
+ * See Documentation/filesystems/relayfs.txt for an overview of relayfs.
+ *
+ * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
+ * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/errno.h>
+#include <linux/stddef.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/relayfs_fs.h>
+#include "relay.h"
+#include "buffers.h"
+
+/**
+ * relay_buf_empty - boolean, is the channel buffer empty?
+ * @buf: channel buffer
+ *
+ * Returns 1 if the buffer is empty, 0 otherwise.
+ */
+int relay_buf_empty(struct rchan_buf *buf)
+{
+ return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
+}
+
+/**
+ * relay_buf_full - boolean, is the channel buffer full?
+ * @buf: channel buffer
+ *
+ * Returns 1 if the buffer is full, 0 otherwise.
+ */
+int relay_buf_full(struct rchan_buf *buf)
+{
+ size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
+ return (ready >= buf->chan->n_subbufs) ? 1 : 0;
+}
+
+/*
+ * High-level relayfs kernel API and associated functions.
+ */
+
+/*
+ * rchan_callback implementations defining default channel behavior. Used
+ * in place of corresponding NULL values in client callback struct.
+ */
+
+/*
+ * subbuf_start() default callback. Does nothing.
+ */
+static int subbuf_start_default_callback (struct rchan_buf *buf,
+ void *subbuf,
+ void *prev_subbuf,
+ size_t prev_padding)
+{
+ if (relay_buf_full(buf))
+ return 0;
+
+ return 1;
+}
+
+/*
+ * buf_mapped() default callback. Does nothing.
+ */
+static void buf_mapped_default_callback(struct rchan_buf *buf,
+ struct file *filp)
+{
+}
+
+/*
+ * buf_unmapped() default callback. Does nothing.
+ */
+static void buf_unmapped_default_callback(struct rchan_buf *buf,
+ struct file *filp)
+{
+}
+
+/* relay channel default callbacks */
+static struct rchan_callbacks default_channel_callbacks = {
+ .subbuf_start = subbuf_start_default_callback,
+ .buf_mapped = buf_mapped_default_callback,
+ .buf_unmapped = buf_unmapped_default_callback,
+};
+
+/**
+ * wakeup_readers - wake up readers waiting on a channel
+ * @private: the channel buffer
+ *
+ * This is the work function used to defer reader waking. The
+ * reason waking is deferred is that calling directly from write
+ * causes problems if you're writing from say the scheduler.
+ */
+static void wakeup_readers(void *private)
+{
+ struct rchan_buf *buf = private;
+ wake_up_interruptible(&buf->read_wait);
+}
+
+/**
+ * __relay_reset - reset a channel buffer
+ * @buf: the channel buffer
+ * @init: 1 if this is a first-time initialization
+ *
+ * See relay_reset for description of effect.
+ */
+static inline void __relay_reset(struct rchan_buf *buf, unsigned int init)
+{
+ size_t i;
+
+ if (init) {
+ init_waitqueue_head(&buf->read_wait);
+ kref_init(&buf->kref);
+ INIT_WORK(&buf->wake_readers, NULL, NULL);
+ } else {
+ cancel_delayed_work(&buf->wake_readers);
+ flush_scheduled_work();
+ }
+
+ buf->subbufs_produced = 0;
+ buf->subbufs_consumed = 0;
+ buf->bytes_consumed = 0;
+ buf->finalized = 0;
+ buf->data = buf->start;
+ buf->offset = 0;
+
+ for (i = 0; i < buf->chan->n_subbufs; i++)
+ buf->padding[i] = 0;
+
+ buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
+}
+
+/**
+ * relay_reset - reset the channel
+ * @chan: the channel
+ *
+ * This has the effect of erasing all data from all channel buffers
+ * and restarting the channel in its initial state. The buffers
+ * are not freed, so any mappings are still in effect.
+ *
+ * NOTE: Care should be taken that the channel isn't actually
+ * being used by anything when this call is made.
+ */
+void relay_reset(struct rchan *chan)
+{
+ unsigned int i;
+
+ if (!chan)
+ return;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ if (!chan->buf[i])
+ continue;
+ __relay_reset(chan->buf[i], 0);
+ }
+}
+
+/**
+ * relay_open_buf - create a new channel buffer in relayfs
+ *
+ * Internal - used by relay_open().
+ */
+static struct rchan_buf *relay_open_buf(struct rchan *chan,
+ const char *filename,
+ struct dentry *parent)
+{
+ struct rchan_buf *buf;
+ struct dentry *dentry;
+
+ /* Create file in fs */
+ dentry = relayfs_create_file(filename, parent, S_IRUSR, chan);
+ if (!dentry)
+ return NULL;
+
+ buf = RELAYFS_I(dentry->d_inode)->buf;
+ buf->dentry = dentry;
+ __relay_reset(buf, 1);
+
+ return buf;
+}
+
+/**
+ * relay_close_buf - close a channel buffer
+ * @buf: channel buffer
+ *
+ * Marks the buffer finalized and restores the default callbacks.
+ * The channel buffer and channel buffer data structure are then freed
+ * automatically when the last reference is given up.
+ */
+static inline void relay_close_buf(struct rchan_buf *buf)
+{
+ buf->finalized = 1;
+ buf->chan->cb = &default_channel_callbacks;
+ cancel_delayed_work(&buf->wake_readers);
+ flush_scheduled_work();
+ kref_put(&buf->kref, relay_remove_buf);
+}
+
+static inline void setup_callbacks(struct rchan *chan,
+ struct rchan_callbacks *cb)
+{
+ if (!cb) {
+ chan->cb = &default_channel_callbacks;
+ return;
+ }
+
+ if (!cb->subbuf_start)
+ cb->subbuf_start = subbuf_start_default_callback;
+ if (!cb->buf_mapped)
+ cb->buf_mapped = buf_mapped_default_callback;
+ if (!cb->buf_unmapped)
+ cb->buf_unmapped = buf_unmapped_default_callback;
+ chan->cb = cb;
+}
+
+/**
+ * relay_open - create a new relayfs channel
+ * @base_filename: base name of files to create
+ * @parent: dentry of parent directory, NULL for root directory
+ * @subbuf_size: size of sub-buffers
+ * @n_subbufs: number of sub-buffers
+ * @cb: client callback functions
+ *
+ * Returns channel pointer if successful, NULL otherwise.
+ *
+ * Creates a channel buffer for each cpu using the sizes and
+ * attributes specified. The created channel buffer files
+ * will be named base_filename0...base_filenameN-1. File
+ * permissions will be S_IRUSR.
+ */
+struct rchan *relay_open(const char *base_filename,
+ struct dentry *parent,
+ size_t subbuf_size,
+ size_t n_subbufs,
+ struct rchan_callbacks *cb)
+{
+ unsigned int i;
+ struct rchan *chan;
+ char *tmpname;
+
+ if (!base_filename)
+ return NULL;
+
+ if (!(subbuf_size && n_subbufs))
+ return NULL;
+
+ chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL);
+ if (!chan)
+ return NULL;
+
+ chan->version = RELAYFS_CHANNEL_VERSION;
+ chan->n_subbufs = n_subbufs;
+ chan->subbuf_size = subbuf_size;
+ chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
+ setup_callbacks(chan, cb);
+ kref_init(&chan->kref);
+
+ tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+ if (!tmpname)
+ goto free_chan;
+
+ for_each_online_cpu(i) {
+ sprintf(tmpname, "%s%d", base_filename, i);
+ chan->buf[i] = relay_open_buf(chan, tmpname, parent);
+ chan->buf[i]->cpu = i;
+ if (!chan->buf[i])
+ goto free_bufs;
+ }
+
+ kfree(tmpname);
+ return chan;
+
+free_bufs:
+ for (i = 0; i < NR_CPUS; i++) {
+ if (!chan->buf[i])
+ break;
+ relay_close_buf(chan->buf[i]);
+ }
+ kfree(tmpname);
+
+free_chan:
+ kref_put(&chan->kref, relay_destroy_channel);
+ return NULL;
+}
+
+/**
+ * relay_switch_subbuf - switch to a new sub-buffer
+ * @buf: channel buffer
+ * @length: size of current event
+ *
+ * Returns either the length passed in or 0 if full.
+
+ * Performs sub-buffer-switch tasks such as invoking callbacks,
+ * updating padding counts, waking up readers, etc.
+ */
+size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
+{
+ void *old, *new;
+ size_t old_subbuf, new_subbuf;
+
+ if (unlikely(length > buf->chan->subbuf_size))
+ goto toobig;
+
+ if (buf->offset != buf->chan->subbuf_size + 1) {
+ buf->prev_padding = buf->chan->subbuf_size - buf->offset;
+ old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
+ buf->padding[old_subbuf] = buf->prev_padding;
+ buf->subbufs_produced++;
+ if (waitqueue_active(&buf->read_wait)) {
+ PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf);
+ schedule_delayed_work(&buf->wake_readers, 1);
+ }
+ }
+
+ old = buf->data;
+ new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
+ new = buf->start + new_subbuf * buf->chan->subbuf_size;
+ buf->offset = 0;
+ if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
+ buf->offset = buf->chan->subbuf_size + 1;
+ return 0;
+ }
+ buf->data = new;
+ buf->padding[new_subbuf] = 0;
+
+ if (unlikely(length + buf->offset > buf->chan->subbuf_size))
+ goto toobig;
+
+ return length;
+
+toobig:
+ printk(KERN_WARNING "relayfs: event too large (%Zd)\n", length);
+ WARN_ON(1);
+ return 0;
+}
+
+/**
+ * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
+ * @chan: the channel
+ * @cpu: the cpu associated with the channel buffer to update
+ * @subbufs_consumed: number of sub-buffers to add to current buf's count
+ *
+ * Adds to the channel buffer's consumed sub-buffer count.
+ * subbufs_consumed should be the number of sub-buffers newly consumed,
+ * not the total consumed.
+ *
+ * NOTE: kernel clients don't need to call this function if the channel
+ * mode is 'overwrite'.
+ */
+void relay_subbufs_consumed(struct rchan *chan,
+ unsigned int cpu,
+ size_t subbufs_consumed)
+{
+ struct rchan_buf *buf;
+
+ if (!chan)
+ return;
+
+ if (cpu >= NR_CPUS || !chan->buf[cpu])
+ return;
+
+ buf = chan->buf[cpu];
+ buf->subbufs_consumed += subbufs_consumed;
+ if (buf->subbufs_consumed > buf->subbufs_produced)
+ buf->subbufs_consumed = buf->subbufs_produced;
+}
+
+/**
+ * relay_destroy_channel - free the channel struct
+ *
+ * Should only be called from kref_put().
+ */
+void relay_destroy_channel(struct kref *kref)
+{
+ struct rchan *chan = container_of(kref, struct rchan, kref);
+ kfree(chan);
+}
+
+/**
+ * relay_close - close the channel
+ * @chan: the channel
+ *
+ * Closes all channel buffers and frees the channel.
+ */
+void relay_close(struct rchan *chan)
+{
+ unsigned int i;
+
+ if (!chan)
+ return;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ if (!chan->buf[i])
+ continue;
+ relay_close_buf(chan->buf[i]);
+ }
+
+ kref_put(&chan->kref, relay_destroy_channel);
+}
+
+/**
+ * relay_flush - close the channel
+ * @chan: the channel
+ *
+ * Flushes all channel buffers i.e. forces buffer switch.
+ */
+void relay_flush(struct rchan *chan)
+{
+ unsigned int i;
+
+ if (!chan)
+ return;
+
+ for (i = 0; i < NR_CPUS; i++) {
+ if (!chan->buf[i])
+ continue;
+ relay_switch_subbuf(chan->buf[i], 0);
+ }
+}
+
+EXPORT_SYMBOL_GPL(relay_open);
+EXPORT_SYMBOL_GPL(relay_close);
+EXPORT_SYMBOL_GPL(relay_flush);
+EXPORT_SYMBOL_GPL(relay_reset);
+EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
+EXPORT_SYMBOL_GPL(relay_switch_subbuf);
+EXPORT_SYMBOL_GPL(relay_buf_full);