perf dsos: Introduce dsos__for_each_dso()

To better abstract the dsos internals, introduce dsos__for_each_dso that
does a callback on each dso.

This also means the read lock can be correctly held.

Signed-off-by: Ian Rogers <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Anne Macedo <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Cc: Ben Gainey <[e-mail]>
Cc: Changbin Du <[e-mail]>
Cc: Chengen Du <[e-mail]>
Cc: Colin Ian King <[e-mail]>
Cc: Ilkka Koskinen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: K Prateek Nayak <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Li Dong <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Markus Elfring <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Paran Lee <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Cc: Song Liu <[e-mail]>
Cc: Sun Haiyong <[e-mail]>
Cc: Thomas Richter <[e-mail]>
Cc: Yang Jihong <[e-mail]>
Cc: Yanteng Si <[e-mail]>
Cc: Yicong Yang <[e-mail]>
Cc: zhaimingbing <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-inject.c

···
 					       process_build_id, machine);
 }
 
+static int guest_session__add_build_ids_cb(struct dso *dso, void *data)
+{
+	struct guest_session *gs = data;
+	struct perf_inject *inject = container_of(gs, struct perf_inject, guest_session);
+
+	if (!dso->has_build_id)
+		return 0;
+
+	return synthesize_build_id(inject, dso, gs->machine_pid);
+
+}
+
 static int guest_session__add_build_ids(struct guest_session *gs)
 {
 	struct perf_inject *inject = container_of(gs, struct perf_inject, guest_session);
-	struct machine *machine = &gs->session->machines.host;
-	struct dso *dso;
-	int ret;
 
 	/* Build IDs will be put in the Build ID feature section */
 	perf_header__set_feat(&inject->session->header, HEADER_BUILD_ID);
 
-	dsos__for_each_with_build_id(dso, &machine->dsos.head) {
-		ret = synthesize_build_id(inject, dso, gs->machine_pid);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
+	return dsos__for_each_dso(&gs->session->machines.host.dsos,
+				  guest_session__add_build_ids_cb,
+				  gs);
 }
 
 static int guest_session__ksymbol_event(struct perf_tool *tool,

tools/perf/util/build-id.c

···
 	return write_padded(fd, name, name_len + 1, len);
 }
 
-static int machine__write_buildid_table(struct machine *machine,
-					struct feat_fd *fd)
+struct machine__write_buildid_table_cb_args {
+	struct machine *machine;
+	struct feat_fd *fd;
+	u16 kmisc, umisc;
+};
+
+static int machine__write_buildid_table_cb(struct dso *dso, void *data)
 {
-	int err = 0;
-	struct dso *pos;
-	u16 kmisc = PERF_RECORD_MISC_KERNEL,
-	    umisc = PERF_RECORD_MISC_USER;
+	struct machine__write_buildid_table_cb_args *args = data;
+	const char *name;
+	size_t name_len;
+	bool in_kernel = false;
+
+	if (!dso->has_build_id)
+		return 0;
+
+	if (!dso->hit && !dso__is_vdso(dso))
+		return 0;
+
+	if (dso__is_vdso(dso)) {
+		name = dso->short_name;
+		name_len = dso->short_name_len;
+	} else if (dso__is_kcore(dso)) {
+		name = args->machine->mmap_name;
+		name_len = strlen(name);
+	} else {
+		name = dso->long_name;
+		name_len = dso->long_name_len;
+	}
+
+	in_kernel = dso->kernel || is_kernel_module(name, PERF_RECORD_MISC_CPUMODE_UNKNOWN);
+	return write_buildid(name, name_len, &dso->bid, args->machine->pid,
+			     in_kernel ? args->kmisc : args->umisc, args->fd);
+}
+
+static int machine__write_buildid_table(struct machine *machine, struct feat_fd *fd)
+{
+	struct machine__write_buildid_table_cb_args args = {
+		.machine = machine,
+		.fd = fd,
+		.kmisc = PERF_RECORD_MISC_KERNEL,
+		.umisc = PERF_RECORD_MISC_USER,
+	};
 
 	if (!machine__is_host(machine)) {
-		kmisc = PERF_RECORD_MISC_GUEST_KERNEL;
-		umisc = PERF_RECORD_MISC_GUEST_USER;
+		args.kmisc = PERF_RECORD_MISC_GUEST_KERNEL;
+		args.umisc = PERF_RECORD_MISC_GUEST_USER;
 	}
 
-	dsos__for_each_with_build_id(pos, &machine->dsos.head) {
-		const char *name;
-		size_t name_len;
-		bool in_kernel = false;
-
-		if (!pos->hit && !dso__is_vdso(pos))
-			continue;
-
-		if (dso__is_vdso(pos)) {
-			name = pos->short_name;
-			name_len = pos->short_name_len;
-		} else if (dso__is_kcore(pos)) {
-			name = machine->mmap_name;
-			name_len = strlen(name);
-		} else {
-			name = pos->long_name;
-			name_len = pos->long_name_len;
-		}
-
-		in_kernel = pos->kernel ||
-				is_kernel_module(name,
-					PERF_RECORD_MISC_CPUMODE_UNKNOWN);
-		err = write_buildid(name, name_len, &pos->bid, machine->pid,
-				    in_kernel ? kmisc : umisc, fd);
-		if (err)
-			break;
-	}
-
-	return err;
+	return dsos__for_each_dso(&machine->dsos, machine__write_buildid_table_cb, &args);
 }
 
 int perf_session__write_buildid_table(struct perf_session *session,

tools/perf/util/dsos.c

···
 	up_read(&dsos->lock);
 	return res;
 }
+
+int dsos__for_each_dso(struct dsos *dsos, int (*cb)(struct dso *dso, void *data), void *data)
+{
+	struct dso *dso;
+
+	down_read(&dsos->lock);
+	list_for_each_entry(dso, &dsos->head, node) {
+		int err;
+
+		err = cb(dso, data);
+		if (err)
+			return err;
+	}
+	up_read(&dsos->lock);
+	return 0;
+}

tools/perf/util/dsos.h

···
 	struct rw_semaphore lock;
 };
 
-#define dsos__for_each_with_build_id(pos, head)	\
-	list_for_each_entry(pos, head, node)	\
-		if (!pos->has_build_id)		\
-			continue;		\
-		else
-
 void dsos__init(struct dsos *dsos);
 void dsos__exit(struct dsos *dsos);
 
···
 				     struct kmod_path *m, const char *filename);
 
 struct dso *dsos__find_kernel_dso(struct dsos *dsos);
+
+int dsos__for_each_dso(struct dsos *dsos, int (*cb)(struct dso *dso, void *data), void *data);
 
 #endif /* __PERF_DSOS */

tools/perf/util/machine.c

···
 	return ret;
 }
 
+static int machine__uses_kcore_cb(struct dso *dso, void *data __maybe_unused)
+{
+	return dso__is_kcore(dso) ? 1 : 0;
+}
+
 static bool machine__uses_kcore(struct machine *machine)
 {
-	struct dso *dso;
-
-	list_for_each_entry(dso, &machine->dsos.head, node) {
-		if (dso__is_kcore(dso))
-			return true;
-	}
-
-	return false;
+	return dsos__for_each_dso(&machine->dsos, machine__uses_kcore_cb, NULL) != 0 ? true : false;
 }
 
 static bool perf_event__is_extra_kernel_mmap(struct machine *machine,
···
 	return sym->name;
 }
 
+struct machine__for_each_dso_cb_args {
+	struct machine *machine;
+	machine__dso_t fn;
+	void *priv;
+};
+
+static int machine__for_each_dso_cb(struct dso *dso, void *data)
+{
+	struct machine__for_each_dso_cb_args *args = data;
+
+	return args->fn(dso, args->machine, args->priv);
+}
+
 int machine__for_each_dso(struct machine *machine, machine__dso_t fn, void *priv)
 {
-	struct dso *pos;
-	int err = 0;
+	struct machine__for_each_dso_cb_args args = {
+		.machine = machine,
+		.fn = fn,
+		.priv = priv,
+	};
 
-	list_for_each_entry(pos, &machine->dsos.head, node) {
-		if (fn(pos, machine, priv))
-			err = -1;
-	}
-	return err;
+	return dsos__for_each_dso(&machine->dsos, machine__for_each_dso_cb, &args);
 }
 
 int machine__for_each_kernel_map(struct machine *machine, machine__map_t fn, void *priv)