Revert "perf thread: Ensure comm_lock held for comm_list"

This reverts commit 8f454c95817d15ee529d58389612ea4b34f5ffb3.

'perf top' is freezing on exit sometimes, bisected to this one, revert.

Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Cc: Bill Wendling <[e-mail]>
Cc: Chaitanya S Prakash <[e-mail]>
Cc: Fei Lang <[e-mail]>
Cc: Howard Chu <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Justin Stitt <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Nathan Chancellor <[e-mail]>
Cc: Nick Desaulniers <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephen Brennan <[e-mail]>
Link: https://lore.kernel.org/r/aDcyvvOKZkRYbjul@x1
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/comm.c

···
 static void comm_strs__remove_if_last(struct comm_str *cs);
 
 static void comm_strs__init(void)
-	NO_THREAD_SAFETY_ANALYSIS /* Inherently single threaded due to pthread_once. */
 {
 	init_rwsem(&_comm_strs.lock);
 	_comm_strs.capacity = 16;
···
 }
 
 static struct comm_str *__comm_strs__find(struct comm_strs *comm_strs, const char *str)
-	SHARED_LOCKS_REQUIRED(comm_strs->lock)
 {
 	struct comm_str **result;
 

tools/perf/util/thread.c

···
 }
 
 struct thread *thread__new(pid_t pid, pid_t tid)
-	NO_THREAD_SAFETY_ANALYSIS /* Allocation/creation is inherently single threaded. */
 {
 	RC_STRUCT(thread) *_thread = zalloc(sizeof(*_thread));
 	struct thread *thread;
···
 
 struct comm *thread__comm(struct thread *thread)
 {
-	struct comm *res = NULL;
+	if (list_empty(thread__comm_list(thread)))
+		return NULL;
 
-	down_read(thread__comm_lock(thread));
-	if (!list_empty(thread__comm_list(thread)))
-		res = list_first_entry(thread__comm_list(thread), struct comm, list);
-	up_read(thread__comm_lock(thread));
-	return res;
+	return list_first_entry(thread__comm_list(thread), struct comm, list);
 }
 
 struct comm *thread__exec_comm(struct thread *thread)
 {
 	struct comm *comm, *last = NULL, *second_last = NULL;
 
-	down_read(thread__comm_lock(thread));
 	list_for_each_entry(comm, thread__comm_list(thread), list) {
-		if (comm->exec) {
-			up_read(thread__comm_lock(thread));
+		if (comm->exec)
 			return comm;
-		}
 		second_last = last;
 		last = comm;
 	}
-	up_read(thread__comm_lock(thread));
 
 	/*
 	 * 'last' with no start time might be the parent's comm of a synthesized
···
 
 static int ____thread__set_comm(struct thread *thread, const char *str,
 				u64 timestamp, bool exec)
-	EXCLUSIVE_LOCKS_REQUIRED(thread__comm_lock(thread))
 {
 	struct comm *new, *curr = thread__comm(thread);
 

tools/perf/util/thread.h

···
 	return &RC_CHK_ACCESS(thread)->namespaces_lock;
 }
 
+static inline struct list_head *thread__comm_list(struct thread *thread)
+{
+	return &RC_CHK_ACCESS(thread)->comm_list;
+}
+
 static inline struct rw_semaphore *thread__comm_lock(struct thread *thread)
 {
 	return &RC_CHK_ACCESS(thread)->comm_lock;
-}
-
-static inline struct list_head *thread__comm_list(struct thread *thread)
-	SHARED_LOCKS_REQUIRED(thread__comm_lock(thread))
-{
-	return &RC_CHK_ACCESS(thread)->comm_list;
 }
 
 static inline u64 thread__db_id(const struct thread *thread)