Merge branch 'tip/tracing/ftrace' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/ftrace

kernel/trace/trace.c

@@ -31,6 +31,7 @@
 #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>
@@ -364,6 +365,25 @@ ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
 	return cnt;
 }
 
+ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
+{
+	int len;
+	void *ret;
+
+	if (s->len <= s->readpos)
+		return -EBUSY;
+
+	len = s->len - s->readpos;
+	if (cnt > len)
+		cnt = len;
+	ret = memcpy(buf, s->buffer + s->readpos, cnt);
+	if (!ret)
+		return -EFAULT;
+
+	s->readpos += len;
+	return cnt;
+}
+
 static void
 trace_print_seq(struct seq_file *m, struct trace_seq *s)
 {
@@ -2368,37 +2388,15 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table)
 	}
 }
 
-/*
- * Consumer reader.
- */
-static ssize_t
-tracing_read_pipe(struct file *filp, char __user *ubuf,
-		  size_t cnt, loff_t *ppos)
+/* Must be called with trace_types_lock mutex held. */
+static int tracing_wait_pipe(struct file *filp)
 {
 	struct trace_iterator *iter = filp->private_data;
-	ssize_t sret;
-
-	/* return any leftover data */
-	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
-	if (sret != -EBUSY)
-		return sret;
-
-	trace_seq_reset(&iter->seq);
 
-	mutex_lock(&trace_types_lock);
-	if (iter->trace->read) {
-		sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
-		if (sret)
-			goto out;
-	}
-
-waitagain:
-	sret = 0;
 	while (trace_empty(iter)) {
 
 		if ((filp->f_flags & O_NONBLOCK)) {
-			sret = -EAGAIN;
-			goto out;
+			return -EAGAIN;
 		}
 
 		/*
@@ -2423,12 +2421,11 @@ waitagain:
 		iter->tr->waiter = NULL;
 
 		if (signal_pending(current)) {
-			sret = -EINTR;
-			goto out;
+			return -EINTR;
 		}
 
 		if (iter->trace != current_trace)
-			goto out;
+			return 0;
 
 		/*
 		 * We block until we read something and tracing is disabled.
@@ -2445,9 +2442,43 @@ waitagain:
 		continue;
 	}
 
+	return 1;
+}
+
+/*
+ * Consumer reader.
+ */
+static ssize_t
+tracing_read_pipe(struct file *filp, char __user *ubuf,
+		  size_t cnt, loff_t *ppos)
+{
+	struct trace_iterator *iter = filp->private_data;
+	ssize_t sret;
+
+	/* return any leftover data */
+	sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
+	if (sret != -EBUSY)
+		return sret;
+
+	trace_seq_reset(&iter->seq);
+
+	mutex_lock(&trace_types_lock);
+	if (iter->trace->read) {
+		sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
+		if (sret)
+			goto out;
+	}
+
+waitagain:
+	sret = tracing_wait_pipe(filp);
+	if (sret <= 0)
+		goto out;
+
 	/* stop when tracing is finished */
-	if (trace_empty(iter))
+	if (trace_empty(iter)) {
+		sret = 0;
 		goto out;
+	}
 
 	if (cnt >= PAGE_SIZE)
 		cnt = PAGE_SIZE - 1;
@@ -2493,6 +2524,135 @@ out:
 	return sret;
 }
 
+static void tracing_pipe_buf_release(struct pipe_inode_info *pipe,
+				     struct pipe_buffer *buf)
+{
+	__free_page(buf->page);
+}
+
+static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
+				     unsigned int idx)
+{
+	__free_page(spd->pages[idx]);
+}
+
+static struct pipe_buf_operations tracing_pipe_buf_ops = {
+	.can_merge		= 0,
+	.map			= generic_pipe_buf_map,
+	.unmap			= generic_pipe_buf_unmap,
+	.confirm		= generic_pipe_buf_confirm,
+	.release		= tracing_pipe_buf_release,
+	.steal			= generic_pipe_buf_steal,
+	.get			= generic_pipe_buf_get,
+};
+
+static size_t
+tracing_fill_pipe_page(struct page *pages, size_t rem,
+			struct trace_iterator *iter)
+{
+	size_t count;
+	int ret;
+
+	/* Seq buffer is page-sized, exactly what we need. */
+	for (;;) {
+		count = iter->seq.len;
+		ret = print_trace_line(iter);
+		count = iter->seq.len - count;
+		if (rem < count) {
+			rem = 0;
+			iter->seq.len -= count;
+			break;
+		}
+		if (ret == TRACE_TYPE_PARTIAL_LINE) {
+			iter->seq.len -= count;
+			break;
+		}
+
+		trace_consume(iter);
+		rem -= count;
+		if (!find_next_entry_inc(iter))	{
+			rem = 0;
+			iter->ent = NULL;
+			break;
+		}
+	}
+
+	return rem;
+}
+
+static ssize_t tracing_splice_read_pipe(struct file *filp,
+					loff_t *ppos,
+					struct pipe_inode_info *pipe,
+					size_t len,
+					unsigned int flags)
+{
+	struct page *pages[PIPE_BUFFERS];
+	struct partial_page partial[PIPE_BUFFERS];
+	struct trace_iterator *iter = filp->private_data;
+	struct splice_pipe_desc spd = {
+		.pages		= pages,
+		.partial	= partial,
+		.nr_pages	= 0, /* This gets updated below. */
+		.flags		= flags,
+		.ops		= &tracing_pipe_buf_ops,
+		.spd_release	= tracing_spd_release_pipe,
+	};
+	ssize_t ret;
+	size_t rem;
+	unsigned int i;
+
+	mutex_lock(&trace_types_lock);
+
+	if (iter->trace->splice_read) {
+		ret = iter->trace->splice_read(iter, filp,
+					       ppos, pipe, len, flags);
+		if (ret)
+			goto out_err;
+	}
+
+	ret = tracing_wait_pipe(filp);
+	if (ret <= 0)
+		goto out_err;
+
+	if (!iter->ent && !find_next_entry_inc(iter)) {
+		ret = -EFAULT;
+		goto out_err;
+	}
+
+	/* Fill as many pages as possible. */
+	for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {
+		pages[i] = alloc_page(GFP_KERNEL);
+		if (!pages[i])
+			break;
+
+		rem = tracing_fill_pipe_page(pages[i], rem, iter);
+
+		/* Copy the data into the page, so we can start over. */
+		ret = trace_seq_to_buffer(&iter->seq,
+					  page_address(pages[i]),
+					  iter->seq.len);
+		if (ret < 0) {
+			__free_page(pages[i]);
+			break;
+		}
+		partial[i].offset = 0;
+		partial[i].len = iter->seq.len;
+
+		trace_seq_reset(&iter->seq);
+	}
+
+	mutex_unlock(&trace_types_lock);
+
+	spd.nr_pages = i;
+
+	return splice_to_pipe(pipe, &spd);
+
+out_err:
+	mutex_unlock(&trace_types_lock);
+
+	return ret;
+}
+
 static ssize_t
 tracing_entries_read(struct file *filp, char __user *ubuf,
 		     size_t cnt, loff_t *ppos)
@@ -2656,6 +2816,7 @@ static struct file_operations tracing_pipe_fops = {
 	.open		= tracing_open_pipe,
 	.poll		= tracing_poll_pipe,
 	.read		= tracing_read_pipe,
+	.splice_read	= tracing_splice_read_pipe,
 	.release	= tracing_release_pipe,
 };
 

kernel/trace/trace.h

@@ -353,6 +353,12 @@ struct tracer {
 	ssize_t			(*read)(struct trace_iterator *iter,
 					struct file *filp, char __user *ubuf,
 					size_t cnt, loff_t *ppos);
+	ssize_t			(*splice_read)(struct trace_iterator *iter,
+					       struct file *filp,
+					       loff_t *ppos,
+					       struct pipe_inode_info *pipe,
+					       size_t len,
+					       unsigned int flags);
 #ifdef CONFIG_FTRACE_STARTUP_TEST
 	int			(*selftest)(struct tracer *trace,
 					    struct trace_array *tr);