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

2 files changed, 196 insertions, 29 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5b1e9a9e9906..d89821283b47 100644
--- a/kernel/trace/trace.c
+++ b/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,
 };
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7b0518adf6d7..dbff0207b213 100644
--- a/kernel/trace/trace.h
+++ b/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);