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authorIngo Molnar <mingo@elte.hu>2009-03-04 11:15:42 +0100
committerIngo Molnar <mingo@elte.hu>2009-03-04 11:15:42 +0100
commit2602c3ba4508f528db024c1d209256513ea05de6 (patch)
tree5713aaad7c95ca810c91fe104407a06b7e4bc4bf
parenta1be621dfacbef0fd374d8acd553d71e07bf29ac (diff)
parent2cadf9135eb3b6d84b6427314be827ddd443c308 (diff)
Merge branch 'rfc/splice/tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace
-rw-r--r--include/linux/ring_buffer.h7
-rw-r--r--kernel/trace/ring_buffer.c118
-rw-r--r--kernel/trace/trace.c274
-rw-r--r--kernel/trace/trace.h1
4 files changed, 357 insertions, 43 deletions
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index f5e793d69bd3..79fcbc4b09d6 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -121,6 +121,9 @@ unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
u64 ring_buffer_time_stamp(int cpu);
void ring_buffer_normalize_time_stamp(int cpu, u64 *ts);
+size_t ring_buffer_page_len(void *page);
+
+
/*
* The below functions are fine to use outside the tracing facility.
*/
@@ -138,8 +141,8 @@ static inline int tracing_is_on(void) { return 0; }
void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
-int ring_buffer_read_page(struct ring_buffer *buffer,
- void **data_page, int cpu, int full);
+int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
+ size_t len, int cpu, int full);
enum ring_buffer_flags {
RB_FL_OVERWRITE = 1 << 0,
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index a8c275c01e83..f2a163db52f9 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -61,6 +61,8 @@ enum {
static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON;
+#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data)
+
/**
* tracing_on - enable all tracing buffers
*
@@ -132,7 +134,7 @@ void ring_buffer_normalize_time_stamp(int cpu, u64 *ts)
}
EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp);
-#define RB_EVNT_HDR_SIZE (sizeof(struct ring_buffer_event))
+#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array))
#define RB_ALIGNMENT 4U
#define RB_MAX_SMALL_DATA 28
@@ -234,6 +236,18 @@ static void rb_init_page(struct buffer_data_page *bpage)
local_set(&bpage->commit, 0);
}
+/**
+ * ring_buffer_page_len - the size of data on the page.
+ * @page: The page to read
+ *
+ * Returns the amount of data on the page, including buffer page header.
+ */
+size_t ring_buffer_page_len(void *page)
+{
+ return local_read(&((struct buffer_data_page *)page)->commit)
+ + BUF_PAGE_HDR_SIZE;
+}
+
/*
* Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing
* this issue out.
@@ -254,7 +268,7 @@ static inline int test_time_stamp(u64 delta)
return 0;
}
-#define BUF_PAGE_SIZE (PAGE_SIZE - offsetof(struct buffer_data_page, data))
+#define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE)
/*
* head_page == tail_page && head == tail then buffer is empty.
@@ -2378,8 +2392,8 @@ static void rb_remove_entries(struct ring_buffer_per_cpu *cpu_buffer,
*/
void *ring_buffer_alloc_read_page(struct ring_buffer *buffer)
{
- unsigned long addr;
struct buffer_data_page *bpage;
+ unsigned long addr;
addr = __get_free_page(GFP_KERNEL);
if (!addr)
@@ -2387,6 +2401,8 @@ void *ring_buffer_alloc_read_page(struct ring_buffer *buffer)
bpage = (void *)addr;
+ rb_init_page(bpage);
+
return bpage;
}
@@ -2406,6 +2422,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
* ring_buffer_read_page - extract a page from the ring buffer
* @buffer: buffer to extract from
* @data_page: the page to use allocated from ring_buffer_alloc_read_page
+ * @len: amount to extract
* @cpu: the cpu of the buffer to extract
* @full: should the extraction only happen when the page is full.
*
@@ -2418,7 +2435,7 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
* rpage = ring_buffer_alloc_read_page(buffer);
* if (!rpage)
* return error;
- * ret = ring_buffer_read_page(buffer, &rpage, cpu, 0);
+ * ret = ring_buffer_read_page(buffer, &rpage, len, cpu, 0);
* if (ret >= 0)
* process_page(rpage, ret);
*
@@ -2435,70 +2452,103 @@ void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data)
* <0 if no data has been transferred.
*/
int ring_buffer_read_page(struct ring_buffer *buffer,
- void **data_page, int cpu, int full)
+ void **data_page, size_t len, int cpu, int full)
{
struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
struct ring_buffer_event *event;
struct buffer_data_page *bpage;
+ struct buffer_page *reader;
unsigned long flags;
+ unsigned int commit;
unsigned int read;
int ret = -1;
+ /*
+ * If len is not big enough to hold the page header, then
+ * we can not copy anything.
+ */
+ if (len <= BUF_PAGE_HDR_SIZE)
+ return -1;
+
+ len -= BUF_PAGE_HDR_SIZE;
+
if (!data_page)
- return 0;
+ return -1;
bpage = *data_page;
if (!bpage)
- return 0;
+ return -1;
spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
- /*
- * rb_buffer_peek will get the next ring buffer if
- * the current reader page is empty.
- */
- event = rb_buffer_peek(buffer, cpu, NULL);
- if (!event)
+ reader = rb_get_reader_page(cpu_buffer);
+ if (!reader)
goto out;
- /* check for data */
- if (!local_read(&cpu_buffer->reader_page->page->commit))
- goto out;
+ event = rb_reader_event(cpu_buffer);
+
+ read = reader->read;
+ commit = rb_page_commit(reader);
- read = cpu_buffer->reader_page->read;
/*
- * If the writer is already off of the read page, then simply
- * switch the read page with the given page. Otherwise
- * we need to copy the data from the reader to the writer.
+ * If this page has been partially read or
+ * if len is not big enough to read the rest of the page or
+ * a writer is still on the page, then
+ * we must copy the data from the page to the buffer.
+ * Otherwise, we can simply swap the page with the one passed in.
*/
- if (cpu_buffer->reader_page == cpu_buffer->commit_page) {
- unsigned int commit = rb_page_commit(cpu_buffer->reader_page);
+ if (read || (len < (commit - read)) ||
+ cpu_buffer->reader_page == cpu_buffer->commit_page) {
struct buffer_data_page *rpage = cpu_buffer->reader_page->page;
+ unsigned int rpos = read;
+ unsigned int pos = 0;
+ unsigned int size;
if (full)
goto out;
- /* The writer is still on the reader page, we must copy */
- memcpy(bpage->data + read, rpage->data + read, commit - read);
- /* consume what was read */
- cpu_buffer->reader_page->read = commit;
+ if (len > (commit - read))
+ len = (commit - read);
+
+ size = rb_event_length(event);
+
+ if (len < size)
+ goto out;
+
+ /* Need to copy one event at a time */
+ do {
+ memcpy(bpage->data + pos, rpage->data + rpos, size);
+
+ len -= size;
+
+ rb_advance_reader(cpu_buffer);
+ rpos = reader->read;
+ pos += size;
+
+ event = rb_reader_event(cpu_buffer);
+ size = rb_event_length(event);
+ } while (len > size);
/* update bpage */
- local_set(&bpage->commit, commit);
- if (!read)
- bpage->time_stamp = rpage->time_stamp;
+ local_set(&bpage->commit, pos);
+ bpage->time_stamp = rpage->time_stamp;
+
+ /* we copied everything to the beginning */
+ read = 0;
} else {
/* swap the pages */
rb_init_page(bpage);
- bpage = cpu_buffer->reader_page->page;
- cpu_buffer->reader_page->page = *data_page;
- cpu_buffer->reader_page->read = 0;
+ bpage = reader->page;
+ reader->page = *data_page;
+ local_set(&reader->write, 0);
+ reader->read = 0;
*data_page = bpage;
+
+ /* update the entry counter */
+ rb_remove_entries(cpu_buffer, bpage, read);
}
ret = read;
- /* update the entry counter */
- rb_remove_entries(cpu_buffer, bpage, read);
out:
spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ea055aa21cd9..12539f72f4a5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -11,31 +11,30 @@
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 William Lee Irwin III
*/
+#include <linux/ring_buffer.h>
#include <linux/utsrelease.h>
+#include <linux/stacktrace.h>
+#include <linux/writeback.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
+#include <linux/irqflags.h>
#include <linux/debugfs.h>
#include <linux/pagemap.h>
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
+#include <linux/kprobes.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
+#include <linux/splice.h>
#include <linux/kdebug.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/gfp.h>
#include <linux/fs.h>
-#include <linux/kprobes.h>
-#include <linux/writeback.h>
-#include <linux/splice.h>
-
-#include <linux/stacktrace.h>
-#include <linux/ring_buffer.h>
-#include <linux/irqflags.h>
#include "trace.h"
#include "trace_output.h"
@@ -3005,6 +3004,246 @@ static struct file_operations tracing_mark_fops = {
.write = tracing_mark_write,
};
+struct ftrace_buffer_info {
+ struct trace_array *tr;
+ void *spare;
+ int cpu;
+ unsigned int read;
+};
+
+static int tracing_buffers_open(struct inode *inode, struct file *filp)
+{
+ int cpu = (int)(long)inode->i_private;
+ struct ftrace_buffer_info *info;
+
+ if (tracing_disabled)
+ return -ENODEV;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ info->tr = &global_trace;
+ info->cpu = cpu;
+ info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
+ /* Force reading ring buffer for first read */
+ info->read = (unsigned int)-1;
+ if (!info->spare)
+ goto out;
+
+ filp->private_data = info;
+
+ return 0;
+
+ out:
+ kfree(info);
+ return -ENOMEM;
+}
+
+static ssize_t
+tracing_buffers_read(struct file *filp, char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ struct ftrace_buffer_info *info = filp->private_data;
+ unsigned int pos;
+ ssize_t ret;
+ size_t size;
+
+ /* Do we have previous read data to read? */
+ if (info->read < PAGE_SIZE)
+ goto read;
+
+ info->read = 0;
+
+ ret = ring_buffer_read_page(info->tr->buffer,
+ &info->spare,
+ count,
+ info->cpu, 0);
+ if (ret < 0)
+ return 0;
+
+ pos = ring_buffer_page_len(info->spare);
+
+ if (pos < PAGE_SIZE)
+ memset(info->spare + pos, 0, PAGE_SIZE - pos);
+
+read:
+ size = PAGE_SIZE - info->read;
+ if (size > count)
+ size = count;
+
+ ret = copy_to_user(ubuf, info->spare + info->read, size);
+ if (ret)
+ return -EFAULT;
+ *ppos += size;
+ info->read += size;
+
+ return size;
+}
+
+static int tracing_buffers_release(struct inode *inode, struct file *file)
+{
+ struct ftrace_buffer_info *info = file->private_data;
+
+ ring_buffer_free_read_page(info->tr->buffer, info->spare);
+ kfree(info);
+
+ return 0;
+}
+
+struct buffer_ref {
+ struct ring_buffer *buffer;
+ void *page;
+ int ref;
+};
+
+static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ struct buffer_ref *ref = (struct buffer_ref *)buf->private;
+
+ if (--ref->ref)
+ return;
+
+ ring_buffer_free_read_page(ref->buffer, ref->page);
+ kfree(ref);
+ buf->private = 0;
+}
+
+static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ return 1;
+}
+
+static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ struct buffer_ref *ref = (struct buffer_ref *)buf->private;
+
+ ref->ref++;
+}
+
+/* Pipe buffer operations for a buffer. */
+static struct pipe_buf_operations buffer_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = generic_pipe_buf_confirm,
+ .release = buffer_pipe_buf_release,
+ .steal = buffer_pipe_buf_steal,
+ .get = buffer_pipe_buf_get,
+};
+
+/*
+ * Callback from splice_to_pipe(), if we need to release some pages
+ * at the end of the spd in case we error'ed out in filling the pipe.
+ */
+static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
+{
+ struct buffer_ref *ref =
+ (struct buffer_ref *)spd->partial[i].private;
+
+ if (--ref->ref)
+ return;
+
+ ring_buffer_free_read_page(ref->buffer, ref->page);
+ kfree(ref);
+ spd->partial[i].private = 0;
+}
+
+static ssize_t
+tracing_buffers_splice_read(struct file *file, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ struct ftrace_buffer_info *info = file->private_data;
+ struct partial_page partial[PIPE_BUFFERS];
+ struct page *pages[PIPE_BUFFERS];
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .partial = partial,
+ .flags = flags,
+ .ops = &buffer_pipe_buf_ops,
+ .spd_release = buffer_spd_release,
+ };
+ struct buffer_ref *ref;
+ int size, i;
+ size_t ret;
+
+ /*
+ * We can't seek on a buffer input
+ */
+ if (unlikely(*ppos))
+ return -ESPIPE;
+
+
+ for (i = 0; i < PIPE_BUFFERS && len; i++, len -= size) {
+ struct page *page;
+ int r;
+
+ ref = kzalloc(sizeof(*ref), GFP_KERNEL);
+ if (!ref)
+ break;
+
+ ref->buffer = info->tr->buffer;
+ ref->page = ring_buffer_alloc_read_page(ref->buffer);
+ if (!ref->page) {
+ kfree(ref);
+ break;
+ }
+
+ r = ring_buffer_read_page(ref->buffer, &ref->page,
+ len, info->cpu, 0);
+ if (r < 0) {
+ ring_buffer_free_read_page(ref->buffer,
+ ref->page);
+ kfree(ref);
+ break;
+ }
+
+ /*
+ * zero out any left over data, this is going to
+ * user land.
+ */
+ size = ring_buffer_page_len(ref->page);
+ if (size < PAGE_SIZE)
+ memset(ref->page + size, 0, PAGE_SIZE - size);
+
+ page = virt_to_page(ref->page);
+
+ spd.pages[i] = page;
+ spd.partial[i].len = PAGE_SIZE;
+ spd.partial[i].offset = 0;
+ spd.partial[i].private = (unsigned long)ref;
+ spd.nr_pages++;
+ }
+
+ spd.nr_pages = i;
+
+ /* did we read anything? */
+ if (!spd.nr_pages) {
+ if (flags & SPLICE_F_NONBLOCK)
+ ret = -EAGAIN;
+ else
+ ret = 0;
+ /* TODO: block */
+ return ret;
+ }
+
+ ret = splice_to_pipe(pipe, &spd);
+
+ return ret;
+}
+
+static const struct file_operations tracing_buffers_fops = {
+ .open = tracing_buffers_open,
+ .read = tracing_buffers_read,
+ .release = tracing_buffers_release,
+ .splice_read = tracing_buffers_splice_read,
+ .llseek = no_llseek,
+};
+
#ifdef CONFIG_DYNAMIC_FTRACE
int __weak ftrace_arch_read_dyn_info(char *buf, int size)
@@ -3399,6 +3638,7 @@ static __init void create_trace_options_dir(void)
static __init int tracer_init_debugfs(void)
{
struct dentry *d_tracer;
+ struct dentry *buffers;
struct dentry *entry;
int cpu;
@@ -3471,6 +3711,26 @@ static __init int tracer_init_debugfs(void)
pr_warning("Could not create debugfs "
"'trace_marker' entry\n");
+ buffers = debugfs_create_dir("binary_buffers", d_tracer);
+
+ if (!buffers)
+ pr_warning("Could not create buffers directory\n");
+ else {
+ int cpu;
+ char buf[64];
+
+ for_each_tracing_cpu(cpu) {
+ sprintf(buf, "%d", cpu);
+
+ entry = debugfs_create_file(buf, 0444, buffers,
+ (void *)(long)cpu,
+ &tracing_buffers_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs buffers "
+ "'%s' entry\n", buf);
+ }
+ }
+
#ifdef CONFIG_DYNAMIC_FTRACE
entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e606633fb498..561bb5c5d988 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -217,6 +217,7 @@ enum trace_flag_type {
*/
struct trace_array_cpu {
atomic_t disabled;
+ void *buffer_page; /* ring buffer spare */
/* these fields get copied into max-trace: */
unsigned long trace_idx;

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