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Commit 3effc2f1 authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarKan Liang <kan.liang@intel.com>
Acked-by: default avatarJiri 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 600a7cfe

tools/perf/util/mmap.c

+4 −46
Original line number Diff line number Diff line
@@ -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;

tools/perf/util/mmap.h

+0 −3
Original line number Diff line number Diff line
@@ -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,