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Message-ID: <aDcyVLVpZRui1ole@x1>
Date: Wed, 28 May 2025 12:57:08 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Namhyung Kim <namhyung@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
Bill Wendling <morbo@...gle.com>,
Chaitanya S Prakash <chaitanyas.prakash@....com>,
Fei Lang <langfei@...wei.com>, Howard Chu <howardchu95@...il.com>,
Ingo Molnar <mingo@...hat.com>,
James Clark <james.clark@...aro.org>, Jiri Olsa <jolsa@...nel.org>,
Justin Stitt <justinstitt@...gle.com>,
Kan Liang <kan.liang@...ux.intel.com>,
Mark Rutland <mark.rutland@....com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
Peter Zijlstra <peterz@...radead.org>,
Stephen Brennan <stephen.s.brennan@...cle.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: [PATCH 1/1] 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 <adrian.hunter@...el.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Cc: Bill Wendling <morbo@...gle.com>
Cc: Chaitanya S Prakash <chaitanyas.prakash@....com>
Cc: Fei Lang <langfei@...wei.com>
Cc: Howard Chu <howardchu95@...il.com>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: James Clark <james.clark@...aro.org>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Justin Stitt <justinstitt@...gle.com>
Cc: Kan Liang <kan.liang@...ux.intel.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Nathan Chancellor <nathan@...nel.org>
Cc: Nick Desaulniers <nick.desaulniers+lkml@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephen Brennan <stephen.s.brennan@...cle.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
tools/perf/util/comm.c | 2 --
tools/perf/util/thread.c | 17 ++++-------------
tools/perf/util/thread.h | 9 ++++-----
3 files changed, 8 insertions(+), 20 deletions(-)
diff --git a/tools/perf/util/comm.c b/tools/perf/util/comm.c
index 9880247a2c3364cb..8aa456d7c2cd2d74 100644
--- a/tools/perf/util/comm.c
+++ b/tools/perf/util/comm.c
@@ -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;
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index c202b98b36c29215..415c0e5d1e751a47 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -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);
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 56e08c8ae005e82b..cd574a896418ac94 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -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)
--
2.49.0
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