Merge tag 'perf-core-for-mingo' of...

Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf improvements and fixes from Arnaldo Carvalho de Melo:

Infrastructure changes:

 * Improve callchain processing by removing unnecessary work. (Frederic Weisbecker)

 * Fix comm override error handling (Frederic Weisbecker)

 * Improve 'perf probe' exit path, release resources (Masami Hiramatsu)

 * Improve libtraceevent plugins exit path, allowing the registering of
   an unregister handler to be called at exit time (Namhyung Kim)

 * Add an alias to the build test makefile (make -C tools/perf build-test)
   (Namhyung Kim)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/lib/traceevent/event-parse.c

@@ -5560,6 +5560,52 @@ int pevent_register_print_function(struct pevent *pevent,
 	return ret;
 }
 
+/**
+ * pevent_unregister_print_function - unregister a helper function
+ * @pevent: the handle to the pevent
+ * @func: the function to process the helper function
+ * @name: the name of the helper function
+ *
+ * This function removes existing print handler for function @name.
+ *
+ * Returns 0 if the handler was removed successully, -1 otherwise.
+ */
+int pevent_unregister_print_function(struct pevent *pevent,
+				     pevent_func_handler func, char *name)
+{
+	struct pevent_function_handler *func_handle;
+
+	func_handle = find_func_handler(pevent, name);
+	if (func_handle && func_handle->func == func) {
+		remove_func_handler(pevent, name);
+		return 0;
+	}
+	return -1;
+}
+
+static struct event_format *pevent_search_event(struct pevent *pevent, int id,
+						const char *sys_name,
+						const char *event_name)
+{
+	struct event_format *event;
+
+	if (id >= 0) {
+		/* search by id */
+		event = pevent_find_event(pevent, id);
+		if (!event)
+			return NULL;
+		if (event_name && (strcmp(event_name, event->name) != 0))
+			return NULL;
+		if (sys_name && (strcmp(sys_name, event->system) != 0))
+			return NULL;
+	} else {
+		event = pevent_find_event_by_name(pevent, sys_name, event_name);
+		if (!event)
+			return NULL;
+	}
+	return event;
+}
+
 /**
  * pevent_register_event_handler - register a way to parse an event
  * @pevent: the handle to the pevent
@@ -5584,20 +5630,9 @@ int pevent_register_event_handler(struct pevent *pevent, int id,
 	struct event_format *event;
 	struct event_handler *handle;
 
-	if (id >= 0) {
-		/* search by id */
-		event = pevent_find_event(pevent, id);
-		if (!event)
-			goto not_found;
-		if (event_name && (strcmp(event_name, event->name) != 0))
-			goto not_found;
-		if (sys_name && (strcmp(sys_name, event->system) != 0))
-			goto not_found;
-	} else {
-		event = pevent_find_event_by_name(pevent, sys_name, event_name);
-		if (!event)
+	event = pevent_search_event(pevent, id, sys_name, event_name);
+	if (event == NULL)
 		goto not_found;
-	}
 
 	pr_stat("overriding event (%d) %s:%s with new print handler",
 		event->id, event->system, event->name);
@@ -5637,6 +5672,79 @@ int pevent_register_event_handler(struct pevent *pevent, int id,
 	return -1;
 }
 
+static int handle_matches(struct event_handler *handler, int id,
+			  const char *sys_name, const char *event_name,
+			  pevent_event_handler_func func, void *context)
+{
+	if (id >= 0 && id != handler->id)
+		return 0;
+
+	if (event_name && (strcmp(event_name, handler->event_name) != 0))
+		return 0;
+
+	if (sys_name && (strcmp(sys_name, handler->sys_name) != 0))
+		return 0;
+
+	if (func != handler->func || context != handler->context)
+		return 0;
+
+	return 1;
+}
+
+/**
+ * pevent_unregister_event_handler - unregister an existing event handler
+ * @pevent: the handle to the pevent
+ * @id: the id of the event to unregister
+ * @sys_name: the system name the handler belongs to
+ * @event_name: the name of the event handler
+ * @func: the function to call to parse the event information
+ * @context: the data to be passed to @func
+ *
+ * This function removes existing event handler (parser).
+ *
+ * If @id is >= 0, then it is used to find the event.
+ * else @sys_name and @event_name are used.
+ *
+ * Returns 0 if handler was removed successfully, -1 if event was not found.
+ */
+int pevent_unregister_event_handler(struct pevent *pevent, int id,
+				    const char *sys_name, const char *event_name,
+				    pevent_event_handler_func func, void *context)
+{
+	struct event_format *event;
+	struct event_handler *handle;
+	struct event_handler **next;
+
+	event = pevent_search_event(pevent, id, sys_name, event_name);
+	if (event == NULL)
+		goto not_found;
+
+	if (event->handler == func && event->context == context) {
+		pr_stat("removing override handler for event (%d) %s:%s. Going back to default handler.",
+			event->id, event->system, event->name);
+
+		event->handler = NULL;
+		event->context = NULL;
+		return 0;
+	}
+
+not_found:
+	for (next = &pevent->handlers; *next; next = &(*next)->next) {
+		handle = *next;
+		if (handle_matches(handle, id, sys_name, event_name,
+				   func, context))
+			break;
+	}
+
+	if (!(*next))
+		return -1;
+
+	*next = handle->next;
+	free_handler(handle);
+
+	return 0;
+}
+
 /**
  * pevent_alloc - create a pevent handle
  */

tools/lib/traceevent/event-parse.h

@@ -624,10 +624,15 @@ int pevent_print_func_field(struct trace_seq *s, const char *fmt,
 int pevent_register_event_handler(struct pevent *pevent, int id,
 				  const char *sys_name, const char *event_name,
 				  pevent_event_handler_func func, void *context);
+int pevent_unregister_event_handler(struct pevent *pevent, int id,
+				    const char *sys_name, const char *event_name,
+				    pevent_event_handler_func func, void *context);
 int pevent_register_print_function(struct pevent *pevent,
 				   pevent_func_handler func,
 				   enum pevent_func_arg_type ret_type,
 				   char *name, ...);
+int pevent_unregister_print_function(struct pevent *pevent,
+				     pevent_func_handler func, char *name);
 
 struct format_field *pevent_find_common_field(struct event_format *event, const char *name);
 struct format_field *pevent_find_field(struct event_format *event, const char *name);

tools/lib/traceevent/plugin_cfg80211.c

@@ -22,3 +22,9 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				       PEVENT_FUNC_ARG_VOID);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_print_function(pevent, process___le16_to_cpup,
+					 "__le16_to_cpup");
+}

tools/lib/traceevent/plugin_function.c

@@ -148,6 +148,9 @@ void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
 {
 	int i, x;
 
+	pevent_unregister_event_handler(pevent, -1, "ftrace", "function",
+					function_handler, NULL);
+
 	for (i = 0; i <= cpus; i++) {
 		for (x = 0; x < fstack[i].size && fstack[i].stack[x]; x++)
 			free(fstack[i].stack[x]);

tools/lib/traceevent/plugin_hrtimer.c

@@ -76,3 +76,13 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				      timer_start_handler, NULL);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_event_handler(pevent, -1,
+					"timer", "hrtimer_expire_entry",
+					timer_expire_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "timer", "hrtimer_start",
+					timer_start_handler, NULL);
+}

tools/lib/traceevent/plugin_jbd2.c

@@ -66,3 +66,12 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				       PEVENT_FUNC_ARG_VOID);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_print_function(pevent, process_jbd2_dev_to_name,
+					 "jbd2_dev_to_name");
+
+	pevent_unregister_print_function(pevent, process_jiffies_to_msecs,
+					 "jiffies_to_msecs");
+}

tools/lib/traceevent/plugin_kmem.c

@@ -70,3 +70,25 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				      call_site_handler, NULL);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_event_handler(pevent, -1, "kmem", "kfree",
+					call_site_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kmem", "kmalloc",
+					call_site_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kmem", "kmalloc_node",
+					call_site_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kmem", "kmem_cache_alloc",
+					call_site_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kmem",
+					"kmem_cache_alloc_node",
+					call_site_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kmem", "kmem_cache_free",
+					call_site_handler, NULL);
+}

tools/lib/traceevent/plugin_kvm.c

@@ -434,3 +434,32 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				       PEVENT_FUNC_ARG_VOID);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_event_handler(pevent, -1, "kvm", "kvm_exit",
+					kvm_exit_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kvm", "kvm_emulate_insn",
+					kvm_emulate_insn_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kvmmmu", "kvm_mmu_get_page",
+					kvm_mmu_get_page_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kvmmmu", "kvm_mmu_sync_page",
+					kvm_mmu_print_role, NULL);
+
+	pevent_unregister_event_handler(pevent, -1,
+					"kvmmmu", "kvm_mmu_unsync_page",
+					kvm_mmu_print_role, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kvmmmu", "kvm_mmu_zap_page",
+					kvm_mmu_print_role, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "kvmmmu",
+			"kvm_mmu_prepare_zap_page", kvm_mmu_print_role,
+			NULL);
+
+	pevent_unregister_print_function(pevent, process_is_writable_pte,
+					 "is_writable_pte");
+}

tools/lib/traceevent/plugin_mac80211.c

@@ -93,3 +93,10 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				      drv_bss_info_changed, NULL);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_event_handler(pevent, -1, "mac80211",
+					"drv_bss_info_changed",
+					drv_bss_info_changed, NULL);
+}

tools/lib/traceevent/plugin_sched_switch.c

@@ -146,3 +146,15 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				      sched_wakeup_handler, NULL);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_event_handler(pevent, -1, "sched", "sched_switch",
+					sched_switch_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "sched", "sched_wakeup",
+					sched_wakeup_handler, NULL);
+
+	pevent_unregister_event_handler(pevent, -1, "sched", "sched_wakeup_new",
+					sched_wakeup_handler, NULL);
+}

tools/lib/traceevent/plugin_scsi.c

@@ -421,3 +421,9 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				       PEVENT_FUNC_ARG_VOID);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_print_function(pevent, process_scsi_trace_parse_cdb,
+					 "scsi_trace_parse_cdb");
+}

tools/lib/traceevent/plugin_xen.c

@@ -128,3 +128,9 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
 				       PEVENT_FUNC_ARG_VOID);
 	return 0;
 }
+
+void PEVENT_PLUGIN_UNLOADER(struct pevent *pevent)
+{
+	pevent_unregister_print_function(pevent, process_xen_hypercall_name,
+					 "xen_hypercall_name");
+}

tools/perf/Makefile

@@ -74,6 +74,12 @@ all tags TAGS:
 clean:
 	$(make)
 
+#
+# The build-test target is not really parallel, don't print the jobs info:
+#
+build-test:
+	@$(MAKE) -f tests/make --no-print-directory
+
 #
 # All other targets get passed through:
 #

tools/perf/builtin-probe.c

@@ -59,7 +59,7 @@ static struct {
 	struct perf_probe_event events[MAX_PROBES];
 	struct strlist *dellist;
 	struct line_range line_range;
-	const char *target;
+	char *target;
 	int max_probe_points;
 	struct strfilter *filter;
 } params;
@@ -98,7 +98,10 @@ static int set_target(const char *ptr)
 	 * short module name.
 	 */
 	if (!params.target && ptr && *ptr == '/') {
-		params.target = ptr;
+		params.target = strdup(ptr);
+		if (!params.target)
+			return -ENOMEM;
+
 		found = 1;
 		buf = ptr + (strlen(ptr) - 3);
 
@@ -116,6 +119,9 @@ static int parse_probe_event_argv(int argc, const char **argv)
 	char *buf;
 
 	found_target = set_target(argv[0]);
+	if (found_target < 0)
+		return found_target;
+
 	if (found_target && argc == 1)
 		return 0;
 
@@ -217,7 +223,6 @@ static int opt_show_lines(const struct option *opt __maybe_unused,
 
 	params.show_lines = true;
 	ret = parse_line_range_desc(str, &params.line_range);
-	INIT_LIST_HEAD(&params.line_range.line_list);
 
 	return ret;
 }
@@ -263,7 +268,28 @@ static int opt_set_filter(const struct option *opt __maybe_unused,
 	return 0;
 }
 
-int cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
+static void init_params(void)
+{
+	line_range__init(&params.line_range);
+}
+
+static void cleanup_params(void)
+{
+	int i;
+
+	for (i = 0; i < params.nevents; i++)
+		clear_perf_probe_event(params.events + i);
+	if (params.dellist)
+		strlist__delete(params.dellist);
+	line_range__clear(&params.line_range);
+	free(params.target);
+	if (params.filter)
+		strfilter__delete(params.filter);
+	memset(&params, 0, sizeof(params));
+}
+
+static int
+__cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 {
 	const char * const probe_usage[] = {
 		"perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
@@ -417,6 +443,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 		ret = show_available_funcs(params.target, params.filter,
 					params.uprobes);
 		strfilter__delete(params.filter);
+		params.filter = NULL;
 		if (ret < 0)
 			pr_err("  Error: Failed to show functions."
 			       " (%d)\n", ret);
@@ -456,6 +483,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 					  params.filter,
 					  params.show_ext_vars);
 		strfilter__delete(params.filter);
+		params.filter = NULL;
 		if (ret < 0)
 			pr_err("  Error: Failed to show vars. (%d)\n", ret);
 		return ret;
@@ -464,7 +492,6 @@ int cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 
 	if (params.dellist) {
 		ret = del_perf_probe_events(params.dellist);
-		strlist__delete(params.dellist);
 		if (ret < 0) {
 			pr_err("  Error: Failed to delete events. (%d)\n", ret);
 			return ret;
@@ -483,3 +510,14 @@ int cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 	}
 	return 0;
 }
+
+int cmd_probe(int argc, const char **argv, const char *prefix)
+{
+	int ret;
+
+	init_params();
+	ret = __cmd_probe(argc, argv, prefix);
+	cleanup_params();
+
+	return ret;
+}

tools/perf/util/callchain.c

@@ -15,6 +15,8 @@
 #include <errno.h>
 #include <math.h>
 
+#include "asm/bug.h"
+
 #include "hist.h"
 #include "util.h"
 #include "sort.h"
@@ -358,19 +360,14 @@ append_chain_children(struct callchain_node *root,
 	/* lookup in childrens */
 	while (*p) {
 		s64 ret;
-		struct callchain_list *cnode;
 
 		parent = *p;
 		rnode = rb_entry(parent, struct callchain_node, rb_node_in);
-		cnode = list_first_entry(&rnode->val, struct callchain_list,
-					 list);
 
-		/* just check first entry */
-		ret = match_chain(node, cnode);
-		if (ret == 0) {
-			append_chain(rnode, cursor, period);
+		/* If at least first entry matches, rely to children */
+		ret = append_chain(rnode, cursor, period);
+		if (ret == 0)
 			goto inc_children_hit;
-		}
 
 		if (ret < 0)
 			p = &parent->rb_left;
@@ -391,11 +388,11 @@ append_chain(struct callchain_node *root,
 	     struct callchain_cursor *cursor,
 	     u64 period)
 {
-	struct callchain_cursor_node *curr_snap = cursor->curr;
 	struct callchain_list *cnode;
 	u64 start = cursor->pos;
 	bool found = false;
 	u64 matches;
+	int cmp = 0;
 
 	/*
 	 * Lookup in the current node
@@ -410,7 +407,8 @@ append_chain(struct callchain_node *root,
 		if (!node)
 			break;
 
-		if (match_chain(node, cnode) != 0)
+		cmp = match_chain(node, cnode);
+		if (cmp)
 			break;
 
 		found = true;
@@ -420,9 +418,8 @@ append_chain(struct callchain_node *root,
 
 	/* matches not, relay no the parent */
 	if (!found) {
-		cursor->curr = curr_snap;
-		cursor->pos = start;
-		return -1;
+		WARN_ONCE(!cmp, "Chain comparison error\n");
+		return cmp;
 	}
 
 	matches = cursor->pos - start;

tools/perf/util/comm.c

@@ -94,19 +94,20 @@ struct comm *comm__new(const char *str, u64 timestamp)
 	return comm;
 }
 
-void comm__override(struct comm *comm, const char *str, u64 timestamp)
+int comm__override(struct comm *comm, const char *str, u64 timestamp)
 {
-	struct comm_str *old = comm->comm_str;
+	struct comm_str *new, *old = comm->comm_str;
 
-	comm->comm_str = comm_str__findnew(str, &comm_str_root);
-	if (!comm->comm_str) {
-		comm->comm_str = old;
-		return;
-	}
+	new = comm_str__findnew(str, &comm_str_root);
+	if (!new)
+		return -ENOMEM;
 
-	comm->start = timestamp;
-	comm_str__get(comm->comm_str);
+	comm_str__get(new);
 	comm_str__put(old);
+	comm->comm_str = new;
+	comm->start = timestamp;
+
+	return 0;
 }
 
 void comm__free(struct comm *comm)

tools/perf/util/comm.h

@@ -16,6 +16,6 @@ struct comm {
 void comm__free(struct comm *comm);
 struct comm *comm__new(const char *str, u64 timestamp);
 const char *comm__str(const struct comm *comm);
-void comm__override(struct comm *comm, const char *str, u64 timestamp);
+int comm__override(struct comm *comm, const char *str, u64 timestamp);
 
 #endif  /* __PERF_COMM_H */

tools/perf/util/probe-event.c

@@ -72,6 +72,7 @@ static int e_snprintf(char *str, size_t size, const char *format, ...)
 static char *synthesize_perf_probe_point(struct perf_probe_point *pp);
 static int convert_name_to_addr(struct perf_probe_event *pev,
 				const char *exec);
+static void clear_probe_trace_event(struct probe_trace_event *tev);
 static struct machine machine;
 
 /* Initialize symbol maps and path of vmlinux/modules */
@@ -172,54 +173,6 @@ const char *kernel_get_module_path(const char *module)
 	return (dso) ? dso->long_name : NULL;
 }
 
-#ifdef HAVE_DWARF_SUPPORT
-/* Copied from unwind.c */
-static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
-				    GElf_Shdr *shp, const char *name)
-{
-	Elf_Scn *sec = NULL;
-
-	while ((sec = elf_nextscn(elf, sec)) != NULL) {
-		char *str;
-
-		gelf_getshdr(sec, shp);
-		str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
-		if (!strcmp(name, str))
-			break;
-	}
-
-	return sec;
-}
-
-static int get_text_start_address(const char *exec, unsigned long *address)
-{
-	Elf *elf;
-	GElf_Ehdr ehdr;
-	GElf_Shdr shdr;
-	int fd, ret = -ENOENT;
-
-	fd = open(exec, O_RDONLY);
-	if (fd < 0)
-		return -errno;
-
-	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
-	if (elf == NULL)
-		return -EINVAL;
-
-	if (gelf_getehdr(elf, &ehdr) == NULL)
-		goto out;
-
-	if (!elf_section_by_name(elf, &ehdr, &shdr, ".text"))
-		goto out;
-
-	*address = shdr.sh_addr - shdr.sh_offset;
-	ret = 0;
-out:
-	elf_end(elf);
-	return ret;
-}
-#endif
-
 static int init_user_exec(void)
 {
 	int ret = 0;
@@ -340,6 +293,34 @@ static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
 	return 0;
 }
 
+static int get_text_start_address(const char *exec, unsigned long *address)
+{
+	Elf *elf;
+	GElf_Ehdr ehdr;
+	GElf_Shdr shdr;
+	int fd, ret = -ENOENT;
+
+	fd = open(exec, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+
+	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+	if (elf == NULL)
+		return -EINVAL;
+
+	if (gelf_getehdr(elf, &ehdr) == NULL)
+		goto out;
+
+	if (!elf_section_by_name(elf, &ehdr, &shdr, ".text", NULL))
+		goto out;
+
+	*address = shdr.sh_addr - shdr.sh_offset;
+	ret = 0;
+out:
+	elf_end(elf);
+	return ret;
+}
+
 static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
 					  int ntevs, const char *exec)
 {
@@ -407,6 +388,14 @@ static int add_module_to_probe_trace_events(struct probe_trace_event *tevs,
 	return ret;
 }
 
+static void clear_probe_trace_events(struct probe_trace_event *tevs, int ntevs)
+{
+	int i;
+
+	for (i = 0; i < ntevs; i++)
+		clear_probe_trace_event(tevs + i);
+}
+
 /* Try to find perf_probe_event with debuginfo */
 static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
 					  struct probe_trace_event **tevs,
@@ -442,6 +431,10 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
 				ret = add_module_to_probe_trace_events(*tevs,
 						 ntevs, target);
 		}
+		if (ret < 0) {
+			clear_probe_trace_events(*tevs, ntevs);
+			zfree(tevs);
+		}
 		return ret < 0 ? ret : ntevs;
 	}
 
@@ -781,6 +774,28 @@ int show_available_vars(struct perf_probe_event *pevs __maybe_unused,
 }
 #endif
 
+void line_range__clear(struct line_range *lr)
+{
+	struct line_node *ln;
+
+	free(lr->function);
+	free(lr->file);
+	free(lr->path);
+	free(lr->comp_dir);
+	while (!list_empty(&lr->line_list)) {
+		ln = list_first_entry(&lr->line_list, struct line_node, list);
+		list_del(&ln->list);
+		free(ln);
+	}
+	memset(lr, 0, sizeof(*lr));
+}
+
+void line_range__init(struct line_range *lr)
+{
+	memset(lr, 0, sizeof(*lr));
+	INIT_LIST_HEAD(&lr->line_list);
+}
+
 static int parse_line_num(char **ptr, int *val, const char *what)
 {
 	const char *start = *ptr;

tools/perf/util/probe-event.h

@@ -120,6 +120,12 @@ extern void clear_perf_probe_event(struct perf_probe_event *pev);
 /* Command string to line-range */
 extern int parse_line_range_desc(const char *cmd, struct line_range *lr);
 
+/* Release line range members */
+extern void line_range__clear(struct line_range *lr);
+
+/* Initialize line range */
+extern void line_range__init(struct line_range *lr);
+
 /* Internal use: Return kernel/module path */
 extern const char *kernel_get_module_path(const char *module);
 

tools/perf/util/symbol-elf.c

@@ -136,9 +136,8 @@ static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
 	return -1;
 }
 
-static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
-				    GElf_Shdr *shp, const char *name,
-				    size_t *idx)
+Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
+			     GElf_Shdr *shp, const char *name, size_t *idx)
 {
 	Elf_Scn *sec = NULL;
 	size_t cnt = 1;

tools/perf/util/symbol.h

@@ -52,6 +52,11 @@ static inline char *bfd_demangle(void __maybe_unused *v,
 # define PERF_ELF_C_READ_MMAP ELF_C_READ
 #endif
 
+#ifdef HAVE_LIBELF_SUPPORT
+extern Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
+				GElf_Shdr *shp, const char *name, size_t *idx);
+#endif
+
 #ifndef DMGL_PARAMS
 #define DMGL_PARAMS      (1 << 0)       /* Include function args */
 #define DMGL_ANSI        (1 << 1)       /* Include const, volatile, etc */

tools/perf/util/thread.c

@@ -66,10 +66,13 @@ struct comm *thread__comm(const struct thread *thread)
 int thread__set_comm(struct thread *thread, const char *str, u64 timestamp)
 {
 	struct comm *new, *curr = thread__comm(thread);
+	int err;
 
 	/* Override latest entry if it had no specific time coverage */
 	if (!curr->start) {
-		comm__override(curr, str, timestamp);
+		err = comm__override(curr, str, timestamp);
+		if (err)
+			return err;
 	} else {
 		new = comm__new(str, timestamp);
 		if (!new)

tools/perf/util/unwind.c

@@ -28,6 +28,7 @@
 #include "session.h"
 #include "perf_regs.h"
 #include "unwind.h"
+#include "symbol.h"
 #include "util.h"
 
 extern int
@@ -158,23 +159,6 @@ static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val,
 	__v;                                                    \
 	})
 
-static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
-				    GElf_Shdr *shp, const char *name)
-{
-	Elf_Scn *sec = NULL;
-
-	while ((sec = elf_nextscn(elf, sec)) != NULL) {
-		char *str;
-
-		gelf_getshdr(sec, shp);
-		str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
-		if (!strcmp(name, str))
-			break;
-	}
-
-	return sec;
-}
-
 static u64 elf_section_offset(int fd, const char *name)
 {
 	Elf *elf;
@@ -190,7 +174,7 @@ static u64 elf_section_offset(int fd, const char *name)
 		if (gelf_getehdr(elf, &ehdr) == NULL)
 			break;
 
-		if (!elf_section_by_name(elf, &ehdr, &shdr, name))
+		if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
 			break;
 
 		offset = shdr.sh_offset;