Commit a02c395c authored Jul 17, 2017 by David Carrillo-Cisneros Committed by Arnaldo Carvalho de Melo Jul 18, 2017

perf header: Make write_pmu_mappings pipe-mode friendly



In pipe-mode, we will operate over a buffer instead of a file descriptor
but write_pmu_mappings uses lseek to move over the perf.data file.

Refactor write_pmu_mappings to avoid the usage of lseek and allow
reusing the same logic in pipe-mode (next patch).

Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
Acked-by: David Ahern <dsahern@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Simon Que <sque@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170718042549.145161-12-davidcc@google.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 48e5fcea

tools/perf/util/header.c

+11 −10

Original line number	Diff line number	Diff line
		@@ -797,11 +797,19 @@ static int write_pmu_mappings(struct feat_fd *ff,
		struct perf_evlist *evlist __maybe_unused)
		{
		struct perf_pmu *pmu = NULL;
		off_t offset = lseek(ff->fd, 0, SEEK_CUR);
		__u32 pmu_num = 0;
		u32 pmu_num = 0;
		int ret;

		/* write real pmu_num later */
		/*
		* Do a first pass to count number of pmu to avoid lseek so this
		* works in pipe mode as well.
		*/
		while ((pmu = perf_pmu__scan(pmu))) {
		if (!pmu->name)
		continue;
		pmu_num++;
		}

		ret = do_write(ff, &pmu_num, sizeof(pmu_num));
		if (ret < 0)
		return ret;
		@@ -809,7 +817,6 @@ static int write_pmu_mappings(struct feat_fd *ff,
		while ((pmu = perf_pmu__scan(pmu))) {
		if (!pmu->name)
		continue;
		pmu_num++;

		ret = do_write(ff, &pmu->type, sizeof(pmu->type));
		if (ret < 0)
		@@ -820,12 +827,6 @@ static int write_pmu_mappings(struct feat_fd *ff,
		return ret;
		}

		if (pwrite(ff->fd, &pmu_num, sizeof(pmu_num), offset) != sizeof(pmu_num)) {
		/* discard all */
		lseek(ff->fd, offset, SEEK_SET);
		return -1;
		}

		return 0;
		}