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@google.com>
Link: https://lore.kernel.org/r/20250823000024.724394-3-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index aad572a78d7fcfdf5091d1d0be09f2e3e0365e08..12387ea88b9a9cd204f8e2c4d0d7490c827acad4 100644 (file)
--- 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 c98104481c8a19e45ace6f38456c6697b1600651..2e0f2004696ae9f6c3204fa36cec3e1cd478d0aa 100644 (file)
--- 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 40ba6a94f7196f9c8a56f1a4f738eeb7985b06f1..a114b3fa1bea1d241a8f214be096dff90ed73388 100644 (file)
--- 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 93baee2eae42ab989f96d5f44e0c9b743643bb9e..6132f1af3e22d3920cc9b1e082f368e368c611f2 100644 (file)
--- 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 a7018a3b0437a699e5d6d4dcf857a1f380fe7a96..bf7f3268b9a2f32be1e0e8098da3158d33ce4de0 100644 (file)
--- 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 a44c70f931568ca58962301014c9d5cfd0dc75d0..bb9ebd84ec2d2a92ab5068f5ed5cc7625f771610 100644 (file)
--- 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 0a7645c7fae7d3151fb8d4f60231ccb0be74fe1d..64c1d65b01496146a31b24cace24d0f86ea3be03 100644 (file)
--- 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 6d2c280a1730c5ef5a90e5448267e5f6c305b2b1..033c79231a54cd4e209e1a824d31c4f10fa63889 100644 (file)
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -902,7 +902,7 @@ out_close:
 
 #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 @@ out:
 
 #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 8d41bd7842dfa31841d255eae6af190afb1891bc..41e4ebe5eac56e70b699ff7e6d11605bc5a86a7e 100644 (file)
--- 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 e816e4220d330d6e2207d86a301be02ed0037432..3fed54de54016227e518f502ae8aa4086362420c 100644 (file)
--- 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 3fb5d146d9b15bd406a3630ac1eb1966f75d110a..3471062187992aa05a09c8d33b6bff79c03d9789 100644 (file)
--- 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 cb2c1ace304aec7cfcb1dc88184244a65b426c0d..fcd1fd13c30e6ec04fbadb1b03b39fa7255b330a 100644 (file)
--- 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);