perf mmap: Discard legacy interface for mmap read

Discards perf_mmap__read_backward() and perf_mmap__read_catchup(). No
tools use them.

There are tools still use perf_mmap__read_forward(). Keep it, but add
comments to point to the new interface for future use.

Signed-off-by: Kan Liang <kan.liang@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-11-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 4 insertions, 49 deletions

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index f804926778b7..91531a7c8fbf 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -63,6 +63,10 @@ static union perf_event *perf_mmap__read(struct perf_mmap *map,
         return event;
 }
 
+/*
+ * legacy interface for mmap read.
+ * Don't use it. Use perf_mmap__read_event().
+ */
 union perf_event *perf_mmap__read_forward(struct perf_mmap *map)
 {
         u64 head;
@@ -78,41 +82,6 @@ union perf_event *perf_mmap__read_forward(struct perf_mmap *map)
         return perf_mmap__read(map, &map->prev, head);
 }
 
-union perf_event *perf_mmap__read_backward(struct perf_mmap *map)
-{
-        u64 head, end;
-
-        /*
-         * Check if event was unmapped due to a POLLHUP/POLLERR.
-         */
-        if (!refcount_read(&map->refcnt))
-                return NULL;
-
-        head = perf_mmap__read_head(map);
-        if (!head)
-                return NULL;
-
-        /*
-         * 'head' pointer starts from 0. Kernel minus sizeof(record) form
-         * it each time when kernel writes to it, so in fact 'head' is
-         * negative. 'end' pointer is made manually by adding the size of
-         * the ring buffer to 'head' pointer, means the validate data can
-         * read is the whole ring buffer. If 'end' is positive, the ring
-         * buffer has not fully filled, so we must adjust 'end' to 0.
-         *
-         * However, since both 'head' and 'end' is unsigned, we can't
-         * simply compare 'end' against 0. Here we compare '-head' and
-         * the size of the ring buffer, where -head is the number of bytes
-         * kernel write to the ring buffer.
-         */
-        if (-head < (u64)(map->mask + 1))
-                end = 0;
-        else
-                end = head + map->mask + 1;
-
-        return perf_mmap__read(map, &map->prev, end);
-}
-
 /*
  * Read event from ring buffer one by one.
  * Return one event for each call.
@@ -152,17 +121,6 @@ union perf_event *perf_mmap__read_event(struct perf_mmap *map,
         return event;
 }
 
-void perf_mmap__read_catchup(struct perf_mmap *map)
-{
-        u64 head;
-
-        if (!refcount_read(&map->refcnt))
-                return;
-
-        head = perf_mmap__read_head(map);
-        map->prev = head;
-}
-
 static bool perf_mmap__empty(struct perf_mmap *map)
 {
         return perf_mmap__read_head(map) == map->prev && !map->auxtrace_mmap.base;
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index 28718543dd42..ec7d3a24e276 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -65,8 +65,6 @@ void perf_mmap__put(struct perf_mmap *map);
 
 void perf_mmap__consume(struct perf_mmap *map, bool overwrite);
 
-void perf_mmap__read_catchup(struct perf_mmap *md);
-
 static inline u64 perf_mmap__read_head(struct perf_mmap *mm)
 {
         struct perf_event_mmap_page *pc = mm->base;
@@ -87,7 +85,6 @@ static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
 }
 
 union perf_event *perf_mmap__read_forward(struct perf_mmap *map);
-union perf_event *perf_mmap__read_backward(struct perf_mmap *map);
 
 union perf_event *perf_mmap__read_event(struct perf_mmap *map,
                                         bool overwrite,