linux-kernel - [PATCH v2 4/5] perf session: Move map/unmap to separate function

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Date:   Tue,  5 Oct 2021 13:27:01 +0300
From:   Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        Alexei Budankov <abudankov@...wei.com>,
        Riccardo Mancini <rickyman7@...il.com>
Subject: [PATCH v2 4/5] perf session: Move map/unmap to separate function

Moving mapping and unmapping code into reader__mmap, so the mmap
code is located together. Moving head/file_offset computation into
reader__mmap function, so all the offset computation is located
together and in one place only.

Suggested-by: Jiri Olsa <jolsa@...nel.org>
Acked-by: Namhyung Kim <namhyung@...il.com>
Reviewed-by: Riccardo Mancini <rickyman7@...il.com>
Tested-by: Riccardo Mancini <rickyman7@...il.com>
Signed-off-by: Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>
---
 tools/perf/util/session.c | 61 ++++++++++++++++++++++-----------------
 1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 53cd7a3b5efd..6c825e4a9dfe 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -2193,13 +2193,9 @@ static int
 reader__init(struct reader *rd, bool *one_mmap)
 {
 	struct reader_state *st = &rd->state;
-	u64 page_offset;
 	char **mmaps = st->mmaps;
 
-	page_offset = page_size * (rd->data_offset / page_size);
-	st->file_offset = page_offset;
-	st->head = rd->data_offset - page_offset;
-
+	st->head = rd->data_offset;
 	st->data_size = rd->data_size + rd->data_offset;
 
 	st->mmap_size = MMAP_SIZE;
@@ -2226,15 +2222,12 @@ reader__exit(struct reader *rd)
 }
 
 static int
-reader__process_events(struct reader *rd, struct perf_session *session,
-		       struct ui_progress *prog)
+reader__mmap(struct reader *rd, struct perf_session *session)
 {
 	struct reader_state *st = &rd->state;
-	u64 page_offset, size;
-	int err = 0, mmap_prot, mmap_flags;
+	int mmap_prot, mmap_flags;
 	char *buf, **mmaps = st->mmaps;
-	union perf_event *event;
-	s64 skip;
+	u64 page_offset;
 
 	mmap_prot  = PROT_READ;
 	mmap_flags = MAP_SHARED;
@@ -2245,20 +2238,45 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 		mmap_prot  |= PROT_WRITE;
 		mmap_flags = MAP_PRIVATE;
 	}
-remap:
+
+	if (mmaps[st->mmap_idx]) {
+		munmap(mmaps[st->mmap_idx], st->mmap_size);
+		mmaps[st->mmap_idx] = NULL;
+	}
+
+	page_offset = page_size * (st->head / page_size);
+	st->file_offset += page_offset;
+	st->head -= page_offset;
+
 	buf = mmap(NULL, st->mmap_size, mmap_prot, mmap_flags, rd->fd,
 		   st->file_offset);
 	if (buf == MAP_FAILED) {
 		pr_err("failed to mmap file\n");
-		err = -errno;
-		goto out;
+		return -errno;
 	}
 	mmaps[st->mmap_idx] = st->mmap_cur = buf;
 	st->mmap_idx = (st->mmap_idx + 1) & (ARRAY_SIZE(st->mmaps) - 1);
 	st->file_pos = st->file_offset + st->head;
+	return 0;
+}
+
+static int
+reader__process_events(struct reader *rd, struct perf_session *session,
+		       struct ui_progress *prog)
+{
+	struct reader_state *st = &rd->state;
+	u64 size;
+	int err = 0;
+	union perf_event *event;
+	s64 skip;
+
+remap:
+	err = reader__mmap(rd, session);
+	if (err)
+		goto out;
 	if (session->one_mmap) {
-		session->one_mmap_addr = buf;
-		session->one_mmap_offset = st->file_offset;
+		session->one_mmap_addr   = rd->state.mmap_cur;
+		session->one_mmap_offset = rd->state.file_offset;
 	}
 
 more:
@@ -2267,17 +2285,8 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 	if (IS_ERR(event))
 		return PTR_ERR(event);
 
-	if (!event) {
-		if (mmaps[st->mmap_idx]) {
-			munmap(mmaps[st->mmap_idx], st->mmap_size);
-			mmaps[st->mmap_idx] = NULL;
-		}
-
-		page_offset = page_size * (st->head / page_size);
-		st->file_offset += page_offset;
-		st->head -= page_offset;
+	if (!event)
 		goto remap;
-	}
 
 	session->active_decomp = &rd->decomp_data;
 	size = event->header.size;
-- 
2.19.0