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Subject[PATCH 1/1] perf bench inject-buildid: Handle writen() errors
Hi Namhyung,

Please check and ack,

- Arnaldo

From 4e5caa5fbe6955dd26336a0b106c52b98c793f3b Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Wed, 25 Aug 2021 11:50:37 -0300
Subject: [PATCH 1/2] perf bench inject-buildid: Handle writen() errors

The build on fedora:35 and fedora:rawhide with clang is failing with:

49 41.00 fedora:35 : FAIL clang version 13.0.0 (Fedora 13.0.0~rc1-1.fc35)
bench/inject-buildid.c:351:6: error: variable 'len' set but not used [-Werror,-Wunused-but-set-variable]
u64 len = 0;
^
1 error generated.
make[3]: *** [/git/perf-5.14.0-rc7/tools/build/Makefile.build:139: bench] Error 2
50 41.11 fedora:rawhide : FAIL clang version 13.0.0 (Fedora 13.0.0~rc1-1.fc35)
bench/inject-buildid.c:351:6: error: variable 'len' set but not used [-Werror,-Wunused-but-set-variable]
u64 len = 0;
^
1 error generated.
make[3]: *** [/git/perf-5.14.0-rc7/tools/build/Makefile.build:139: bench] Error 2

That 'len' variable is not used at all, so just make sure all the
synthesize_RECORD() routines return ssize_t to propagate the writen()
return, as it may fail, ditch the 'ret' var and bail out if those
routines fail.

Fixes: 0bf02a0d80427f26 ("perf bench: Add build-id injection benchmark")
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/bench/inject-buildid.c | 52 ++++++++++++++++++-------------
1 file changed, 30 insertions(+), 22 deletions(-)

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index 55d373b75791b0e4..17672790f1231acc 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -133,7 +133,7 @@ static u64 dso_map_addr(struct bench_dso *dso)
return 0x400000ULL + dso->ino * 8192ULL;
}

-static u32 synthesize_attr(struct bench_data *data)
+static ssize_t synthesize_attr(struct bench_data *data)
{
union perf_event event;

@@ -151,7 +151,7 @@ static u32 synthesize_attr(struct bench_data *data)
return writen(data->input_pipe[1], &event, event.header.size);
}

-static u32 synthesize_fork(struct bench_data *data)
+static ssize_t synthesize_fork(struct bench_data *data)
{
union perf_event event;

@@ -169,8 +169,7 @@ static u32 synthesize_fork(struct bench_data *data)
return writen(data->input_pipe[1], &event, event.header.size);
}

-static u32 synthesize_mmap(struct bench_data *data, struct bench_dso *dso,
- u64 timestamp)
+static ssize_t synthesize_mmap(struct bench_data *data, struct bench_dso *dso, u64 timestamp)
{
union perf_event event;
size_t len = offsetof(struct perf_record_mmap2, filename);
@@ -198,23 +197,25 @@ static u32 synthesize_mmap(struct bench_data *data, struct bench_dso *dso,

if (len > sizeof(event.mmap2)) {
/* write mmap2 event first */
- writen(data->input_pipe[1], &event, len - bench_id_hdr_size);
+ if (writen(data->input_pipe[1], &event, len - bench_id_hdr_size) < 0)
+ return -1;
/* zero-fill sample id header */
memset(id_hdr_ptr, 0, bench_id_hdr_size);
/* put timestamp in the right position */
ts_idx = (bench_id_hdr_size / sizeof(u64)) - 2;
id_hdr_ptr[ts_idx] = timestamp;
- writen(data->input_pipe[1], id_hdr_ptr, bench_id_hdr_size);
- } else {
- ts_idx = (len / sizeof(u64)) - 2;
- id_hdr_ptr[ts_idx] = timestamp;
- writen(data->input_pipe[1], &event, len);
+ if (writen(data->input_pipe[1], id_hdr_ptr, bench_id_hdr_size) < 0)
+ return -1;
+
+ return len;
}
- return len;
+
+ ts_idx = (len / sizeof(u64)) - 2;
+ id_hdr_ptr[ts_idx] = timestamp;
+ return writen(data->input_pipe[1], &event, len);
}

-static u32 synthesize_sample(struct bench_data *data, struct bench_dso *dso,
- u64 timestamp)
+static ssize_t synthesize_sample(struct bench_data *data, struct bench_dso *dso, u64 timestamp)
{
union perf_event event;
struct perf_sample sample = {
@@ -233,7 +234,7 @@ static u32 synthesize_sample(struct bench_data *data, struct bench_dso *dso,
return writen(data->input_pipe[1], &event, event.header.size);
}

-static u32 synthesize_flush(struct bench_data *data)
+static ssize_t synthesize_flush(struct bench_data *data)
{
struct perf_event_header header = {
.size = sizeof(header),
@@ -348,14 +349,16 @@ static int inject_build_id(struct bench_data *data, u64 *max_rss)
int status;
unsigned int i, k;
struct rusage rusage;
- u64 len = 0;

/* this makes the child to run */
if (perf_header__write_pipe(data->input_pipe[1]) < 0)
return -1;

- len += synthesize_attr(data);
- len += synthesize_fork(data);
+ if (synthesize_attr(data) < 0)
+ return -1;
+
+ if (synthesize_fork(data) < 0)
+ return -1;

for (i = 0; i < nr_mmaps; i++) {
int idx = rand() % (nr_dsos - 1);
@@ -363,13 +366,18 @@ static int inject_build_id(struct bench_data *data, u64 *max_rss)
u64 timestamp = rand() % 1000000;

pr_debug2(" [%d] injecting: %s\n", i+1, dso->name);
- len += synthesize_mmap(data, dso, timestamp);
+ if (synthesize_mmap(data, dso, timestamp) < 0)
+ return -1;

- for (k = 0; k < nr_samples; k++)
- len += synthesize_sample(data, dso, timestamp + k * 1000);
+ for (k = 0; k < nr_samples; k++) {
+ if (synthesize_sample(data, dso, timestamp + k * 1000) < 0)
+ return -1;
+ }

- if ((i + 1) % 10 == 0)
- len += synthesize_flush(data);
+ if ((i + 1) % 10 == 0) {
+ if (synthesize_flush(data) < 0)
+ return -1;
+ }
}

/* this makes the child to finish */
--
2.31.1
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