Commit 24bcc31f authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

Revert "perf thread: Ensure comm_lock held for comm_list" 

This reverts commit 8f454c95.

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

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Bill Wendling <morbo@google.com>
Cc: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
Cc: Fei Lang <langfei@huawei.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Link: https://lore.kernel.org/r/aDcyvvOKZkRYbjul@x1


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 6dd7a0fd

tools/perf/util/comm.c

+0 −2
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ static struct comm_strs { 
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;
@@ -120,7 +119,6 @@ static void comm_strs__remove_if_last(struct comm_str *cs) 
}



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

+4 −13
Original line number Diff line number Diff line
@@ -41,7 +41,6 @@ int thread__init_maps(struct thread *thread, struct machine *machine) 
}



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;
@@ -203,29 +202,22 @@ int thread__set_namespaces(struct thread *thread, u64 timestamp, 


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
@@ -241,7 +233,6 @@ struct comm *thread__exec_comm(struct thread *thread) 


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

+4 −5
Original line number Diff line number Diff line
@@ -236,15 +236,14 @@ static inline struct rw_semaphore *thread__namespaces_lock(struct thread *thread 
	return &RC_CHK_ACCESS(thread)->namespaces_lock;

}



static inline struct rw_semaphore *thread__comm_lock(struct thread *thread)

static inline struct list_head *thread__comm_list(struct thread *thread)

{

	return &RC_CHK_ACCESS(thread)->comm_lock;

	return &RC_CHK_ACCESS(thread)->comm_list;

}



static inline struct list_head *thread__comm_list(struct thread *thread)

	SHARED_LOCKS_REQUIRED(thread__comm_lock(thread))

static inline struct rw_semaphore *thread__comm_lock(struct thread *thread)

{

	return &RC_CHK_ACCESS(thread)->comm_list;

	return &RC_CHK_ACCESS(thread)->comm_lock;

}



static inline u64 thread__db_id(const struct thread *thread)