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-rw-r--r--kernel/relay.c182
1 files changed, 152 insertions, 30 deletions
diff --git a/kernel/relay.c b/kernel/relay.c
index 7de644cdec43..8d13a7855c08 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -407,6 +407,35 @@ void relay_reset(struct rchan *chan)
}
EXPORT_SYMBOL_GPL(relay_reset);
+static inline void relay_set_buf_dentry(struct rchan_buf *buf,
+ struct dentry *dentry)
+{
+ buf->dentry = dentry;
+ buf->dentry->d_inode->i_size = buf->early_bytes;
+}
+
+static struct dentry *relay_create_buf_file(struct rchan *chan,
+ struct rchan_buf *buf,
+ unsigned int cpu)
+{
+ struct dentry *dentry;
+ char *tmpname;
+
+ tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
+ if (!tmpname)
+ return NULL;
+ snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
+
+ /* Create file in fs */
+ dentry = chan->cb->create_buf_file(tmpname, chan->parent,
+ S_IRUSR, buf,
+ &chan->is_global);
+
+ kfree(tmpname);
+
+ return dentry;
+}
+
/*
* relay_open_buf - create a new relay channel buffer
*
@@ -416,45 +445,34 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
{
struct rchan_buf *buf = NULL;
struct dentry *dentry;
- char *tmpname;
if (chan->is_global)
return chan->buf[0];
- tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL);
- if (!tmpname)
- goto end;
- snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
-
buf = relay_create_buf(chan);
if (!buf)
- goto free_name;
+ return NULL;
+
+ if (chan->has_base_filename) {
+ dentry = relay_create_buf_file(chan, buf, cpu);
+ if (!dentry)
+ goto free_buf;
+ relay_set_buf_dentry(buf, dentry);
+ }
buf->cpu = cpu;
__relay_reset(buf, 1);
- /* Create file in fs */
- dentry = chan->cb->create_buf_file(tmpname, chan->parent, S_IRUSR,
- buf, &chan->is_global);
- if (!dentry)
- goto free_buf;
-
- buf->dentry = dentry;
-
if(chan->is_global) {
chan->buf[0] = buf;
buf->cpu = 0;
}
- goto free_name;
+ return buf;
free_buf:
relay_destroy_buf(buf);
- buf = NULL;
-free_name:
- kfree(tmpname);
-end:
- return buf;
+ return NULL;
}
/**
@@ -537,8 +555,8 @@ static int __cpuinit relay_hotcpu_callback(struct notifier_block *nb,
/**
* relay_open - create a new relay channel
- * @base_filename: base name of files to create
- * @parent: dentry of parent directory, %NULL for root directory
+ * @base_filename: base name of files to create, %NULL for buffering only
+ * @parent: dentry of parent directory, %NULL for root directory or buffer
* @subbuf_size: size of sub-buffers
* @n_subbufs: number of sub-buffers
* @cb: client callback functions
@@ -560,8 +578,6 @@ struct rchan *relay_open(const char *base_filename,
{
unsigned int i;
struct rchan *chan;
- if (!base_filename)
- return NULL;
if (!(subbuf_size && n_subbufs))
return NULL;
@@ -576,7 +592,10 @@ struct rchan *relay_open(const char *base_filename,
chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
chan->parent = parent;
chan->private_data = private_data;
- strlcpy(chan->base_filename, base_filename, NAME_MAX);
+ if (base_filename) {
+ chan->has_base_filename = 1;
+ strlcpy(chan->base_filename, base_filename, NAME_MAX);
+ }
setup_callbacks(chan, cb);
kref_init(&chan->kref);
@@ -604,6 +623,94 @@ free_bufs:
}
EXPORT_SYMBOL_GPL(relay_open);
+struct rchan_percpu_buf_dispatcher {
+ struct rchan_buf *buf;
+ struct dentry *dentry;
+};
+
+/* Called in atomic context. */
+static void __relay_set_buf_dentry(void *info)
+{
+ struct rchan_percpu_buf_dispatcher *p = info;
+
+ relay_set_buf_dentry(p->buf, p->dentry);
+}
+
+/**
+ * relay_late_setup_files - triggers file creation
+ * @chan: channel to operate on
+ * @base_filename: base name of files to create
+ * @parent: dentry of parent directory, %NULL for root directory
+ *
+ * Returns 0 if successful, non-zero otherwise.
+ *
+ * Use to setup files for a previously buffer-only channel.
+ * Useful to do early tracing in kernel, before VFS is up, for example.
+ */
+int relay_late_setup_files(struct rchan *chan,
+ const char *base_filename,
+ struct dentry *parent)
+{
+ int err = 0;
+ unsigned int i, curr_cpu;
+ unsigned long flags;
+ struct dentry *dentry;
+ struct rchan_percpu_buf_dispatcher disp;
+
+ if (!chan || !base_filename)
+ return -EINVAL;
+
+ strlcpy(chan->base_filename, base_filename, NAME_MAX);
+
+ mutex_lock(&relay_channels_mutex);
+ /* Is chan already set up? */
+ if (unlikely(chan->has_base_filename))
+ return -EEXIST;
+ chan->has_base_filename = 1;
+ chan->parent = parent;
+ curr_cpu = get_cpu();
+ /*
+ * The CPU hotplug notifier ran before us and created buffers with
+ * no files associated. So it's safe to call relay_setup_buf_file()
+ * on all currently online CPUs.
+ */
+ for_each_online_cpu(i) {
+ if (unlikely(!chan->buf[i])) {
+ printk(KERN_ERR "relay_late_setup_files: CPU %u "
+ "has no buffer, it must have!\n", i);
+ BUG();
+ err = -EINVAL;
+ break;
+ }
+
+ dentry = relay_create_buf_file(chan, chan->buf[i], i);
+ if (unlikely(!dentry)) {
+ err = -EINVAL;
+ break;
+ }
+
+ if (curr_cpu == i) {
+ local_irq_save(flags);
+ relay_set_buf_dentry(chan->buf[i], dentry);
+ local_irq_restore(flags);
+ } else {
+ disp.buf = chan->buf[i];
+ disp.dentry = dentry;
+ smp_mb();
+ /* relay_channels_mutex must be held, so wait. */
+ err = smp_call_function_single(i,
+ __relay_set_buf_dentry,
+ &disp, 1);
+ }
+ if (unlikely(err))
+ break;
+ }
+ put_cpu();
+ mutex_unlock(&relay_channels_mutex);
+
+ return err;
+}
+
/**
* relay_switch_subbuf - switch to a new sub-buffer
* @buf: channel buffer
@@ -627,8 +734,13 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
buf->padding[old_subbuf] = buf->prev_padding;
buf->subbufs_produced++;
- buf->dentry->d_inode->i_size += buf->chan->subbuf_size -
- buf->padding[old_subbuf];
+ if (buf->dentry)
+ buf->dentry->d_inode->i_size +=
+ buf->chan->subbuf_size -
+ buf->padding[old_subbuf];
+ else
+ buf->early_bytes += buf->chan->subbuf_size -
+ buf->padding[old_subbuf];
smp_mb();
if (waitqueue_active(&buf->read_wait))
/*
@@ -832,6 +944,10 @@ static void relay_file_read_consume(struct rchan_buf *buf,
size_t n_subbufs = buf->chan->n_subbufs;
size_t read_subbuf;
+ if (buf->subbufs_produced == buf->subbufs_consumed &&
+ buf->offset == buf->bytes_consumed)
+ return;
+
if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
relay_subbufs_consumed(buf->chan, buf->cpu, 1);
buf->bytes_consumed = 0;
@@ -863,6 +979,8 @@ static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
relay_file_read_consume(buf, read_pos, 0);
+ consumed = buf->subbufs_consumed;
+
if (unlikely(buf->offset > subbuf_size)) {
if (produced == consumed)
return 0;
@@ -881,8 +999,12 @@ static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
if (consumed > produced)
produced += n_subbufs * subbuf_size;
- if (consumed == produced)
+ if (consumed == produced) {
+ if (buf->offset == subbuf_size &&
+ buf->subbufs_produced > buf->subbufs_consumed)
+ return 1;
return 0;
+ }
return 1;
}
@@ -1237,4 +1359,4 @@ static __init int relay_init(void)
return 0;
}
-module_init(relay_init);
+early_initcall(relay_init);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-30 20:37:10 +0100