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author | Stephane Eranian <eranian@google.com> | 2012-05-15 13:11:11 +0200 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2012-06-11 11:20:21 -0300 |
commit | fc3e4d077d5c7a7bc1ad5bc143895b4e070e5a8b (patch) | |
tree | 47c8345fbc1615a4118183d0eb1355ab2399651c | |
parent | 80c0120a3cca30166c0ab8b24e44be67e97b79af (diff) | |
download | op-kernel-dev-fc3e4d077d5c7a7bc1ad5bc143895b4e070e5a8b.zip op-kernel-dev-fc3e4d077d5c7a7bc1ad5bc143895b4e070e5a8b.tar.gz |
perf stat: Fix default output file
The following commit:
commit 56f3bae70638b33477a6015fd362ccfe354fd3ee
Author: Jim Cromie <jim.cromie@gmail.com>
Date: Wed Sep 7 17:14:00 2011 -0600
perf stat: Add --log-fd <N> option to redirect stderr elsewhere
introduced a bug in the way perf stat outputs the results by default,
i.e., without the --log-fd or --output option. It would default to
writing to file descriptor 0, i.e., stdin. Writing to stdin is allowed
and is equivalent to writing to stdout. However, there is a major
difference for any script that was already capturing the output of perf
stat via redirection:
perf stat >/tmp/log .... or perf stat 2>/tmp/log ....
They would not capture anything anymore. They would have to do:
perf stat 0>/tmp/log ...
This breaks compatibility with existing scripts and does not look very
natural.
This patch fixes the problem by looking at output_fd only when it was
modified by user (> 0). It also checks that the value if positive.
Passing --log-fd 0 is ignored.
I would also argue that defaulting to stderr for the results is not the
right thing to do, though this patch does not address this specific
issue.
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jim Cromie <jim.cromie@gmail.com>
Link: http://lkml.kernel.org/r/20120515111111.GA9870@quad
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r-- | tools/perf/builtin-stat.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 2625899..07b5c77 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -1179,6 +1179,12 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used) fprintf(stderr, "cannot use both --output and --log-fd\n"); usage_with_options(stat_usage, options); } + + if (output_fd < 0) { + fprintf(stderr, "argument to --log-fd must be a > 0\n"); + usage_with_options(stat_usage, options); + } + if (!output) { struct timespec tm; mode = append_file ? "a" : "w"; @@ -1190,7 +1196,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used) } clock_gettime(CLOCK_REALTIME, &tm); fprintf(output, "# started on %s\n", ctime(&tm.tv_sec)); - } else if (output_fd != 2) { + } else if (output_fd > 0) { mode = append_file ? "a" : "w"; output = fdopen(output_fd, mode); if (!output) { |