perf inject: Overhaul handling of pipe files

Previously inject->is_pipe was set if the input or output were a
pipe. Determining the input was a pipe had to be done prior to
starting the session and opening the file. This was done by comparing
the input file name with '-' but it fails if the pipe file is written
to disk.

Opening a pipe file from disk will correctly set perf_data.is_pipe, but
this is too late for 'perf inject' and results in a broken file. A
workaround is 'cat pipe_perf|perf inject -i - ...'.

This change removes inject->is_pipe and changes the dependent
conditions to use the is_pipe flag on the input
(inject->session->data) and output files (inject->output). This
ensures the is_pipe condition reflects things like the header being
read.

The change removes the use of perf file header repiping, that is
writing the file header out while reading it in. The case of input
pipe and output file cannot repipe as the attributes for the file are
unknown. To resolve this, write the file header when writing to disk
and as the attributes may be unknown, write them after the data.

Update sessions repipe variable to be trace_event_repipe as those are
the only events now impacted by it. Update __perf_session__new as the
repipe_fd no longer needs passing. Fully removing repipe from session
header reading will be done in a later change.

Committer testing:

  root@number:~# perf record -e syscalls:sys_enter_*sleep/max-stack=4/ -o - sleep 0.01 | perf report -i -
  # To display the perf.data header info, please use --header/--header-only options.
  #
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.050 MB - ]
  #
  # Total Lost Samples: 0
  #
  # Samples: 1  of event 'syscalls:sys_enter_clock_nanosleep'
  # Event count (approx.): 1
  #
  # Overhead  Command  Shared Object  Symbol
  # ........  .......  .............  ...............................
  #
     100.00%  sleep    libc.so.6      [.] clock_nanosleep@GLIBC_2.2.5
              |
              ---__libc_start_main@@GLIBC_2.34
                 __libc_start_call_main
                 0x562fc2560a9f
                 clock_nanosleep@GLIBC_2.2.5

  #
  # (Tip: Create an archive with symtabs to analyse on other machine: perf archive)
  #
  root@number:~# perf record -e syscalls:sys_enter_*sleep/max-stack=4/ -o - sleep 0.01 > pipe.data
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.050 MB - ]
  root@number:~# perf report --stdio -i pipe.data
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 1  of event 'syscalls:sys_enter_clock_nanosleep'
  # Event count (approx.): 1
  #
  # Overhead  Command  Shared Object  Symbol
  # ........  .......  .............  ...............................
  #
     100.00%  sleep    libc.so.6      [.] clock_nanosleep@GLIBC_2.2.5
              |
              ---__libc_start_main@@GLIBC_2.34
                 __libc_start_call_main
                 0x55f775975a9f
                 clock_nanosleep@GLIBC_2.2.5

  #
  # (Tip: To set sampling period of individual events use perf record -e cpu/cpu-cycles,period=100001/,cpu/branches,period=10001/ ...)
  #
  root@number:~#

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Link: https://lore.kernel.org/r/20240829150154.37929-7-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 4eb39463067e..59e2f37c1cb4 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3818,10 +3818,11 @@ size_t perf_session__data_offset(const struct evlist *evlist)
 int perf_session__inject_header(struct perf_session *session,
 				struct evlist *evlist,
 				int fd,
-				struct feat_copier *fc)
+				struct feat_copier *fc,
+				bool write_attrs_after_data)
 {
 	return perf_session__do_write_header(session, evlist, fd, true, fc,
-					     /*write_attrs_after_data=*/false);
+					     write_attrs_after_data);
 }
 
 static int perf_header__getbuffer64(struct perf_header *header,
@@ -4145,7 +4146,7 @@ static int perf_header__read_pipe(struct perf_session *session, int repipe_fd)
 	struct perf_pipe_file_header f_header;
 
 	if (perf_file_header__read_pipe(&f_header, header, session->data,
-					session->repipe, repipe_fd) < 0) {
+					/*repipe=*/false, repipe_fd) < 0) {
 		pr_debug("incompatible file format\n");
 		return -EINVAL;
 	}
@@ -4560,15 +4561,14 @@ int perf_event__process_tracing_data(struct perf_session *session,
 		      SEEK_SET);
 	}
 
-	size_read = trace_report(fd, &session->tevent,
-				 session->repipe);
+	size_read = trace_report(fd, &session->tevent, session->trace_event_repipe);
 	padding = PERF_ALIGN(size_read, sizeof(u64)) - size_read;
 
 	if (readn(fd, buf, padding) < 0) {
 		pr_err("%s: reading input file", __func__);
 		return -1;
 	}
-	if (session->repipe) {
+	if (session->trace_event_repipe) {
 		int retw = write(STDOUT_FILENO, buf, padding);
 		if (retw <= 0 || retw != padding) {
 			pr_err("%s: repiping tracing data padding", __func__);