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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>
This commit is contained in:
Kan Liang 2018-01-18 13:26:25 -08:00 committed by Arnaldo Carvalho de Melo
parent 600a7cfe88
commit 3effc2f165
2 changed files with 4 additions and 49 deletions
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50
tools/perf/util/mmap.c
View File

@ -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;

3
tools/perf/util/mmap.h
View File

@ -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,