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 1/4] perf inject: Use perf_data__read() for auxtrace
Date:   Thu, 26 Jan 2023 16:19:48 -0800
Message-Id: <20230127001951.3432374-2-namhyung@kernel.org>
In-Reply-To: <20230127001951.3432374-1-namhyung@kernel.org>
References: <20230127001951.3432374-1-namhyung@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

In copy_bytes(), it reads the data from the (input) fd and writes it to
the output file.  But it does with the read(2) unconditionally which
caused a problem of mixing buffered vs unbuffered I/O together.

You can see the problem when using pipes.

  $ perf record -e intel_pt// -o- true | perf inject -b > /dev/null
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
  0x45c0 [0x30]: failed to process type: 71

It should use perf_data__read() to honor the 'use_stdio' setting.

Fixes: 601366678c93 ("perf data: Allow to use stdio functions for pipe mode")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/builtin-inject.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 3f4e4dd5abf3..f8182417b734 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -215,14 +215,14 @@ static int perf_event__repipe_event_update(struct perf_tool *tool,
 
 #ifdef HAVE_AUXTRACE_SUPPORT
 
-static int copy_bytes(struct perf_inject *inject, int fd, off_t size)
+static int copy_bytes(struct perf_inject *inject, struct perf_data *data, off_t size)
 {
 	char buf[4096];
 	ssize_t ssz;
 	int ret;
 
 	while (size > 0) {
-		ssz = read(fd, buf, min(size, (off_t)sizeof(buf)));
+		ssz = perf_data__read(data, buf, min(size, (off_t)sizeof(buf)));
 		if (ssz < 0)
 			return -errno;
 		ret = output_bytes(inject, buf, ssz);
@@ -260,7 +260,7 @@ static s64 perf_event__repipe_auxtrace(struct perf_session *session,
 		ret = output_bytes(inject, event, event->header.size);
 		if (ret < 0)
 			return ret;
-		ret = copy_bytes(inject, perf_data__fd(session->data),
+		ret = copy_bytes(inject, session->data,
 				 event->auxtrace.size);
 	} else {
 		ret = output_bytes(inject, event,
-- 
2.39.1.456.gfc5497dd1b-goog