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Message-ID: <20250823000024.724394-3-irogers@google.com>
Date: Fri, 22 Aug 2025 17:00:24 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>, James Clark <james.clark@...aro.org>,
Collin Funk <collin.funk1@...il.com>, "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
Stephen Brennan <stephen.s.brennan@...cle.com>, Palmer Dabbelt <palmer@...belt.com>,
Haibo Xu <haibo1.xu@...el.com>, Dmitry Vyukov <dvyukov@...gle.com>, Song Liu <song@...nel.org>,
Thomas Falcon <thomas.falcon@...el.com>, linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v1 2/2] perf symbol: Add blocking argument to filename__read_build_id
When synthesizing build-ids, for build ID mmap2 events, they will be
added for data mmaps if -d/--data is specified. The files opened for
their build IDs may block on the open causing perf to hang during
synthesis. There is some robustness in existing calls to
filename__read_build_id by checking the file path is to a regular
file, which unfortunately fails for symlinks. Rather than adding more
is_regular_file calls, switch filename__read_build_id to take a
"block" argument and specify O_NONBLOCK when this is false. The
existing is_regular_file checking callers and the event synthesis
callers are made to pass false and thereby avoiding the hang.
Fixes: 53b00ff358dc ("perf record: Make --buildid-mmap the default")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/perf/bench/inject-buildid.c | 2 +-
tools/perf/builtin-buildid-cache.c | 8 ++++----
tools/perf/builtin-inject.c | 4 ++--
tools/perf/tests/sdt.c | 2 +-
tools/perf/util/build-id.c | 4 ++--
tools/perf/util/debuginfo.c | 8 ++++++--
tools/perf/util/dsos.c | 4 ++--
tools/perf/util/symbol-elf.c | 9 +++++----
tools/perf/util/symbol-minimal.c | 6 +++---
tools/perf/util/symbol.c | 8 ++++----
tools/perf/util/symbol.h | 2 +-
tools/perf/util/synthetic-events.c | 2 +-
12 files changed, 32 insertions(+), 27 deletions(-)
diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7f..12387ea88b9a 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -85,7 +85,7 @@ static int add_dso(const char *fpath, const struct stat *sb __maybe_unused,
if (typeflag == FTW_D || typeflag == FTW_SL)
return 0;
- if (filename__read_build_id(fpath, &bid) < 0)
+ if (filename__read_build_id(fpath, &bid, /*block=*/true) < 0)
return 0;
dso->name = realpath(fpath, NULL);
diff --git a/tools/perf/builtin-buildid-cache.c b/tools/perf/builtin-buildid-cache.c
index c98104481c8a..2e0f2004696a 100644
--- a/tools/perf/builtin-buildid-cache.c
+++ b/tools/perf/builtin-buildid-cache.c
@@ -180,7 +180,7 @@ static int build_id_cache__add_file(const char *filename, struct nsinfo *nsi)
struct nscookie nsc;
nsinfo__mountns_enter(nsi, &nsc);
- err = filename__read_build_id(filename, &bid);
+ err = filename__read_build_id(filename, &bid, /*block=*/true);
nsinfo__mountns_exit(&nsc);
if (err < 0) {
pr_debug("Couldn't read a build-id in %s\n", filename);
@@ -204,7 +204,7 @@ static int build_id_cache__remove_file(const char *filename, struct nsinfo *nsi)
int err;
nsinfo__mountns_enter(nsi, &nsc);
- err = filename__read_build_id(filename, &bid);
+ err = filename__read_build_id(filename, &bid, /*block=*/true);
nsinfo__mountns_exit(&nsc);
if (err < 0) {
pr_debug("Couldn't read a build-id in %s\n", filename);
@@ -280,7 +280,7 @@ static bool dso__missing_buildid_cache(struct dso *dso, int parm __maybe_unused)
if (!dso__build_id_filename(dso, filename, sizeof(filename), false))
return true;
- if (filename__read_build_id(filename, &bid) == -1) {
+ if (filename__read_build_id(filename, &bid, /*block=*/true) == -1) {
if (errno == ENOENT)
return false;
@@ -309,7 +309,7 @@ static int build_id_cache__update_file(const char *filename, struct nsinfo *nsi)
int err;
nsinfo__mountns_enter(nsi, &nsc);
- err = filename__read_build_id(filename, &bid);
+ err = filename__read_build_id(filename, &bid, /*block=*/true);
nsinfo__mountns_exit(&nsc);
if (err < 0) {
pr_debug("Couldn't read a build-id in %s\n", filename);
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 40ba6a94f719..a114b3fa1bea 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -680,12 +680,12 @@ static int dso__read_build_id(struct dso *dso)
mutex_lock(dso__lock(dso));
nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
- if (filename__read_build_id(dso__long_name(dso), &bid) > 0)
+ if (filename__read_build_id(dso__long_name(dso), &bid, /*block=*/true) > 0)
dso__set_build_id(dso, &bid);
else if (dso__nsinfo(dso)) {
char *new_name = dso__filename_with_chroot(dso, dso__long_name(dso));
- if (new_name && filename__read_build_id(new_name, &bid) > 0)
+ if (new_name && filename__read_build_id(new_name, &bid, /*block=*/true) > 0)
dso__set_build_id(dso, &bid);
free(new_name);
}
diff --git a/tools/perf/tests/sdt.c b/tools/perf/tests/sdt.c
index 93baee2eae42..6132f1af3e22 100644
--- a/tools/perf/tests/sdt.c
+++ b/tools/perf/tests/sdt.c
@@ -31,7 +31,7 @@ static int build_id_cache__add_file(const char *filename)
struct build_id bid = { .size = 0, };
int err;
- err = filename__read_build_id(filename, &bid);
+ err = filename__read_build_id(filename, &bid, /*block=*/true);
if (err < 0) {
pr_debug("Failed to read build id of %s\n", filename);
return err;
diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index a7018a3b0437..bf7f3268b9a2 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -115,7 +115,7 @@ int filename__snprintf_build_id(const char *pathname, char *sbuild_id, size_t sb
struct build_id bid = { .size = 0, };
int ret;
- ret = filename__read_build_id(pathname, &bid);
+ ret = filename__read_build_id(pathname, &bid, /*block=*/true);
if (ret < 0)
return ret;
@@ -841,7 +841,7 @@ static int filename__read_build_id_ns(const char *filename,
int ret;
nsinfo__mountns_enter(nsi, &nsc);
- ret = filename__read_build_id(filename, bid);
+ ret = filename__read_build_id(filename, bid, /*block=*/true);
nsinfo__mountns_exit(&nsc);
return ret;
diff --git a/tools/perf/util/debuginfo.c b/tools/perf/util/debuginfo.c
index a44c70f93156..bb9ebd84ec2d 100644
--- a/tools/perf/util/debuginfo.c
+++ b/tools/perf/util/debuginfo.c
@@ -110,8 +110,12 @@ struct debuginfo *debuginfo__new(const char *path)
if (!dso)
goto out;
- /* Set the build id for DSO_BINARY_TYPE__BUILDID_DEBUGINFO */
- if (is_regular_file(path) && filename__read_build_id(path, &bid) > 0)
+ /*
+ * Set the build id for DSO_BINARY_TYPE__BUILDID_DEBUGINFO. Don't block
+ * incase the path isn't for a regular file.
+ */
+ assert(!dso__has_build_id(dso));
+ if (filename__read_build_id(path, &bid, /*block=*/false) > 0)
dso__set_build_id(dso, &bid);
for (type = distro_dwarf_types;
diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
index 0a7645c7fae7..64c1d65b0149 100644
--- a/tools/perf/util/dsos.c
+++ b/tools/perf/util/dsos.c
@@ -81,13 +81,13 @@ static int dsos__read_build_ids_cb(struct dso *dso, void *data)
return 0;
}
nsinfo__mountns_enter(dso__nsinfo(dso), &nsc);
- if (filename__read_build_id(dso__long_name(dso), &bid) > 0) {
+ if (filename__read_build_id(dso__long_name(dso), &bid, /*block=*/true) > 0) {
dso__set_build_id(dso, &bid);
args->have_build_id = true;
} else if (errno == ENOENT && dso__nsinfo(dso)) {
char *new_name = dso__filename_with_chroot(dso, dso__long_name(dso));
- if (new_name && filename__read_build_id(new_name, &bid) > 0) {
+ if (new_name && filename__read_build_id(new_name, &bid, /*block=*/true) > 0) {
dso__set_build_id(dso, &bid);
args->have_build_id = true;
}
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 6d2c280a1730..033c79231a54 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -902,7 +902,7 @@ static int read_build_id(const char *filename, struct build_id *bid)
#else // HAVE_LIBBFD_BUILDID_SUPPORT
-static int read_build_id(const char *filename, struct build_id *bid)
+static int read_build_id(const char *filename, struct build_id *bid, bool block)
{
size_t size = sizeof(bid->data);
int fd, err = -1;
@@ -911,7 +911,7 @@ static int read_build_id(const char *filename, struct build_id *bid)
if (size < BUILD_ID_SIZE)
goto out;
- fd = open(filename, O_RDONLY);
+ fd = open(filename, block ? O_RDONLY : (O_RDONLY | O_NONBLOCK));
if (fd < 0)
goto out;
@@ -934,7 +934,7 @@ static int read_build_id(const char *filename, struct build_id *bid)
#endif // HAVE_LIBBFD_BUILDID_SUPPORT
-int filename__read_build_id(const char *filename, struct build_id *bid)
+int filename__read_build_id(const char *filename, struct build_id *bid, bool block)
{
struct kmod_path m = { .name = NULL, };
char path[PATH_MAX];
@@ -958,9 +958,10 @@ int filename__read_build_id(const char *filename, struct build_id *bid)
}
close(fd);
filename = path;
+ block = true;
}
- err = read_build_id(filename, bid);
+ err = read_build_id(filename, bid, block);
if (m.comp)
unlink(filename);
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index 8d41bd7842df..41e4ebe5eac5 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -85,7 +85,7 @@ int filename__read_debuglink(const char *filename __maybe_unused,
/*
* Just try PT_NOTE header otherwise fails
*/
-int filename__read_build_id(const char *filename, struct build_id *bid)
+int filename__read_build_id(const char *filename, struct build_id *bid, bool block)
{
int fd, ret = -1;
bool need_swap = false, elf32;
@@ -102,7 +102,7 @@ int filename__read_build_id(const char *filename, struct build_id *bid)
void *phdr, *buf = NULL;
ssize_t phdr_size, ehdr_size, buf_size = 0;
- fd = open(filename, O_RDONLY);
+ fd = open(filename, block ? O_RDONLY : (O_RDONLY | O_NONBLOCK));
if (fd < 0)
return -1;
@@ -323,7 +323,7 @@ int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
if (ret >= 0)
RC_CHK_ACCESS(dso)->is_64_bit = ret;
- if (filename__read_build_id(ss->name, &bid) > 0)
+ if (filename__read_build_id(ss->name, &bid, /*block=*/true) > 0)
dso__set_build_id(dso, &bid);
return 0;
}
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index e816e4220d33..3fed54de5401 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1869,14 +1869,14 @@ int dso__load(struct dso *dso, struct map *map)
/*
* Read the build id if possible. This is required for
- * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
+ * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work. Don't block in case path
+ * isn't for a regular file.
*/
- if (!dso__has_build_id(dso) &&
- is_regular_file(dso__long_name(dso))) {
+ if (!dso__has_build_id(dso)) {
struct build_id bid = { .size = 0, };
__symbol__join_symfs(name, PATH_MAX, dso__long_name(dso));
- if (filename__read_build_id(name, &bid) > 0)
+ if (filename__read_build_id(name, &bid, /*block=*/false) > 0)
dso__set_build_id(dso, &bid);
}
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 3fb5d146d9b1..347106218799 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -140,7 +140,7 @@ struct symbol *dso__next_symbol(struct symbol *sym);
enum dso_type dso__type_fd(int fd);
-int filename__read_build_id(const char *filename, struct build_id *id);
+int filename__read_build_id(const char *filename, struct build_id *id, bool block);
int sysfs__read_build_id(const char *filename, struct build_id *bid);
int modules__parse(const char *filename, void *arg,
int (*process_module)(void *arg, const char *name,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index cb2c1ace304a..fcd1fd13c30e 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -401,7 +401,7 @@ static void perf_record_mmap2__read_build_id(struct perf_record_mmap2 *event,
nsi = nsinfo__new(event->pid);
nsinfo__mountns_enter(nsi, &nc);
- rc = filename__read_build_id(event->filename, &bid) > 0 ? 0 : -1;
+ rc = filename__read_build_id(event->filename, &bid, /*block=*/false) > 0 ? 0 : -1;
nsinfo__mountns_exit(&nc);
nsinfo__put(nsi);
--
2.51.0.rc2.233.g662b1ed5c5-goog
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