ftrace: convert single large buffer into single pages.

Allocating large buffers for the tracer may fail easily.
This patch converts the buffer from a large ordered allocation
to single pages. It uses the struct page LRU field to link the
pages together.

Later patches may also implement dynamic increasing and decreasing
of the trace buffers.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 6 insertions, 2 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3173a93561d4..83e257e38084 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -54,9 +54,11 @@ struct trace_entry {
  */
 struct trace_array_cpu {
         void                    *trace;
+        void                    *trace_current;
+        unsigned                trace_current_idx;
+        struct list_head        trace_pages;
         unsigned long           trace_idx;
         atomic_t                disabled;
-        atomic_t                underrun;
         unsigned long           saved_latency;
         unsigned long           critical_start;
         unsigned long           critical_end;
@@ -112,8 +114,10 @@ struct trace_iterator {
         unsigned long           iter_flags;
         loff_t                  pos;
         unsigned long           next_idx[NR_CPUS];
+        struct list_head        *next_page[NR_CPUS];
+        unsigned                next_page_idx[NR_CPUS];
+        long                    idx;
         int                     cpu;
-        int                     idx;
 };
 
 void notrace tracing_reset(struct trace_array_cpu *data);