Sender: Namhyung Kim <namhyung@gmail.com>
From:   Namhyung Kim <namhyung@kernel.org>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>
Cc:     Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Ian Rogers <irogers@google.com>,
        linux-perf-users@vger.kernel.org, Leo Yan <leo.yan@linaro.org>,
        James Clark <james.clark@arm.com>,
        Stephane Eranian <eranian@google.com>
Subject: [PATCH 3/4] perf session: Avoid calling lseek(2) for pipe
Date:   Thu, 26 Jan 2023 16:19:50 -0800
Message-Id: <20230127001951.3432374-4-namhyung@kernel.org>
In-Reply-To: <20230127001951.3432374-1-namhyung@kernel.org>
References: <20230127001951.3432374-1-namhyung@kernel.org>
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We should not call lseek(2) for pipes as it won't work.  And we already
in the proper place to read the data for AUXTRACE.  Add the comment like
in the PERF_RECORD_HEADER_TRACING_DATA.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/session.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 7c021c6cedb9..fdfe772f2699 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1699,8 +1699,13 @@ static s64 perf_session__process_user_event(struct perf_session *session,
 	case PERF_RECORD_AUXTRACE_INFO:
 		return tool->auxtrace_info(session, event);
 	case PERF_RECORD_AUXTRACE:
-		/* setup for reading amidst mmap */
-		lseek(fd, file_offset + event->header.size, SEEK_SET);
+		/*
+		 * Setup for reading amidst mmap, but only when we
+		 * are in 'file' mode.  The 'pipe' fd is in proper
+		 * place already.
+		 */
+		if (!perf_data__is_pipe(session->data))
+			lseek(fd, file_offset + event->header.size, SEEK_SET);
 		return tool->auxtrace(session, event);
 	case PERF_RECORD_AUXTRACE_ERROR:
 		perf_session__auxtrace_error_inc(session, event);
-- 
2.39.1.456.gfc5497dd1b-goog