6.6-stable review patch. If anyone has any objections, please let me know.
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From: Ian Rogers irogers@google.com
[ Upstream commit 9ffa6c7512ca7aaeb30e596e2c247cb1fae7123a ]
'struct thread' values hold onto references to mmaps, DSOs, etc. When a thread exits it is necessary to clean all of this memory up by removing the thread from the machine's threads. Some tools require this doesn't happen, such as auxtrace events, 'perf report' if offcpu events exist or if a task list is being generated, so add a 'struct symbol_conf' member to make the behavior optional. When an exited thread is left in the machine's threads, mark it as exited.
This change relates to commit 40826c45eb0b8856 ("perf thread: Remove notion of dead threads") . Dead threads were removed as they had a reference count of 0 and were difficult to reason about with the reference count checker. Here a thread is removed from threads when it exits, unless via symbol_conf the exited thread isn't remove and is marked as exited. Reference counting behaves as it normally does.
Reviewed-by: Adrian Hunter adrian.hunter@intel.com Signed-off-by: Ian Rogers irogers@google.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Andi Kleen ak@linux.intel.com Cc: Athira Jajeev atrajeev@linux.vnet.ibm.com Cc: Changbin Du changbin.du@huawei.com Cc: Colin Ian King colin.i.king@gmail.com Cc: Dmitrii Dolgov 9erthalion6@gmail.com Cc: German Gomez german.gomez@arm.com Cc: Huacai Chen chenhuacai@kernel.org Cc: Ingo Molnar mingo@redhat.com Cc: James Clark james.clark@arm.com Cc: Jiri Olsa jolsa@kernel.org Cc: K Prateek Nayak kprateek.nayak@amd.com Cc: Kajol Jain kjain@linux.ibm.com Cc: Kan Liang kan.liang@linux.intel.com Cc: Leo Yan leo.yan@linaro.org Cc: Li Dong lidong@vivo.com Cc: Liam Howlett liam.howlett@oracle.com Cc: Mark Rutland mark.rutland@arm.com Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Miguel Ojeda ojeda@kernel.org Cc: Ming Wang wangming01@loongson.cn Cc: Namhyung Kim namhyung@kernel.org Cc: Nick Terrell terrelln@fb.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Peter Zijlstra peterz@infradead.org Cc: Ravi Bangoria ravi.bangoria@amd.com Cc: Sandipan Das sandipan.das@amd.com Cc: Sean Christopherson seanjc@google.com Cc: Steinar H. Gunderson sesse@google.com Cc: Vincent Whitchurch vincent.whitchurch@axis.com Cc: Wenyu Liu liuwenyu7@huawei.com Cc: Yang Jihong yangjihong1@huawei.com Link: https://lore.kernel.org/r/20231102175735.2272696-6-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Stable-dep-of: aaf494cf483a ("perf annotate: Fix annotation_calc_lines() to pass correct address to get_srcline()") Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/builtin-report.c | 7 +++++++ tools/perf/util/machine.c | 10 +++++++--- tools/perf/util/session.c | 5 +++++ tools/perf/util/symbol_conf.h | 3 ++- tools/perf/util/thread.h | 14 ++++++++++++++ 5 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c index dcedfe00f04db..749246817aed3 100644 --- a/tools/perf/builtin-report.c +++ b/tools/perf/builtin-report.c @@ -1411,6 +1411,13 @@ int cmd_report(int argc, const char **argv) if (ret < 0) goto exit;
+ /* + * tasks_mode require access to exited threads to list those that are in + * the data file. Off-cpu events are synthesized after other events and + * reference exited threads. + */ + symbol_conf.keep_exited_threads = true; + annotation_options__init(&report.annotation_opts);
ret = perf_config(report__config, &report); diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index e6a8d758f6fe4..7c6874804660e 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -2158,9 +2158,13 @@ int machine__process_exit_event(struct machine *machine, union perf_event *event if (dump_trace) perf_event__fprintf_task(event, stdout);
- if (thread != NULL) - thread__put(thread); - + if (thread != NULL) { + if (symbol_conf.keep_exited_threads) + thread__set_exited(thread, /*exited=*/true); + else + machine__remove_thread(machine, thread); + } + thread__put(thread); return 0; }
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index 1e9aa8ed15b64..c6afba7ab1a51 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -115,6 +115,11 @@ static int perf_session__open(struct perf_session *session, int repipe_fd) return -1; }
+ if (perf_header__has_feat(&session->header, HEADER_AUXTRACE)) { + /* Auxiliary events may reference exited threads, hold onto dead ones. */ + symbol_conf.keep_exited_threads = true; + } + if (perf_data__is_pipe(data)) return 0;
diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h index 2b2fb9e224b00..6040286e07a65 100644 --- a/tools/perf/util/symbol_conf.h +++ b/tools/perf/util/symbol_conf.h @@ -43,7 +43,8 @@ struct symbol_conf { disable_add2line_warn, buildid_mmap2, guest_code, - lazy_load_kernel_maps; + lazy_load_kernel_maps, + keep_exited_threads; const char *vmlinux_name, *kallsyms_name, *source_prefix, diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h index e79225a0ea46b..0df775b5c1105 100644 --- a/tools/perf/util/thread.h +++ b/tools/perf/util/thread.h @@ -36,13 +36,22 @@ struct thread_rb_node { };
DECLARE_RC_STRUCT(thread) { + /** @maps: mmaps associated with this thread. */ struct maps *maps; pid_t pid_; /* Not all tools update this */ + /** @tid: thread ID number unique to a machine. */ pid_t tid; + /** @ppid: parent process of the process this thread belongs to. */ pid_t ppid; int cpu; int guest_cpu; /* For QEMU thread */ refcount_t refcnt; + /** + * @exited: Has the thread had an exit event. Such threads are usually + * removed from the machine's threads but some events/tools require + * access to dead threads. + */ + bool exited; bool comm_set; int comm_len; struct list_head namespaces_list; @@ -189,6 +198,11 @@ static inline refcount_t *thread__refcnt(struct thread *thread) return &RC_CHK_ACCESS(thread)->refcnt; }
+static inline void thread__set_exited(struct thread *thread, bool exited) +{ + RC_CHK_ACCESS(thread)->exited = exited; +} + static inline bool thread__comm_set(const struct thread *thread) { return RC_CHK_ACCESS(thread)->comm_set;