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Subject[PATCH RFC 05/10] perf tools: lock to protect thread list
Date
From: Kan Liang <kan.liang@intel.com>

Add two locks to protect namespaces_list and comm_list.

The comm which is used in db-export are not protected. Because the
multithread code will not touch it. It can be added later if required.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
tools/perf/ui/browsers/hists.c | 2 +-
tools/perf/util/thread.c | 60 +++++++++++++++++++++++++++++++++---------
tools/perf/util/thread.h | 6 +++--
3 files changed, 52 insertions(+), 16 deletions(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 13dfb0a..429e1dd 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -2370,7 +2370,7 @@ static int perf_evsel_browser_title(struct hist_browser *browser,
char unit;
int printed;
const struct dso *dso = hists->dso_filter;
- const struct thread *thread = hists->thread_filter;
+ struct thread *thread = hists->thread_filter;
int socket_id = hists->socket_filter;
unsigned long nr_samples = hists->stats.nr_events[PERF_RECORD_SAMPLE];
u64 nr_events = hists->stats.total_period;
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index b7957da..25830b2 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -45,6 +45,8 @@ struct thread *thread__new(pid_t pid, pid_t tid)
thread->cpu = -1;
INIT_LIST_HEAD(&thread->namespaces_list);
INIT_LIST_HEAD(&thread->comm_list);
+ pthread_mutex_init(&thread->namespaces_lock, NULL);
+ pthread_mutex_init(&thread->comm_lock, NULL);

comm_str = malloc(32);
if (!comm_str)
@@ -83,15 +85,21 @@ void thread__delete(struct thread *thread)
map_groups__put(thread->mg);
thread->mg = NULL;
}
+ pthread_mutex_lock(&thread->namespaces_lock);
list_for_each_entry_safe(namespaces, tmp_namespaces,
&thread->namespaces_list, list) {
list_del(&namespaces->list);
namespaces__free(namespaces);
}
+ pthread_mutex_unlock(&thread->namespaces_lock);
+
+ pthread_mutex_lock(&thread->comm_lock);
list_for_each_entry_safe(comm, tmp_comm, &thread->comm_list, list) {
list_del(&comm->list);
comm__free(comm);
}
+ pthread_mutex_unlock(&thread->comm_lock);
+
unwind__finish_access(thread);
nsinfo__zput(thread->nsinfo);

@@ -128,11 +136,17 @@ struct namespaces *thread__namespaces(const struct thread *thread)
int thread__set_namespaces(struct thread *thread, u64 timestamp,
struct namespaces_event *event)
{
- struct namespaces *new, *curr = thread__namespaces(thread);
+ struct namespaces *new, *curr;
+
+ pthread_mutex_lock(&thread->namespaces_lock);
+
+ curr = thread__namespaces(thread);

new = namespaces__new(event);
- if (!new)
+ if (!new) {
+ pthread_mutex_unlock(&thread->namespaces_lock);
return -ENOMEM;
+ }

list_add(&new->list, &thread->namespaces_list);

@@ -146,17 +160,21 @@ int thread__set_namespaces(struct thread *thread, u64 timestamp,
curr->end_time = timestamp;
}

+ pthread_mutex_unlock(&thread->namespaces_lock);
+
return 0;
}

-void thread__namespaces_id(const struct thread *thread,
+void thread__namespaces_id(struct thread *thread,
u64 *dev, u64 *ino)
{
struct namespaces *ns;

+ pthread_mutex_lock(&thread->namespaces_lock);
ns = thread__namespaces(thread);
*dev = ns ? ns->link_info[CGROUP_NS_INDEX].dev : 0;
*ino = ns ? ns->link_info[CGROUP_NS_INDEX].ino : 0;
+ pthread_mutex_unlock(&thread->namespaces_lock);
}

struct comm *thread__comm(const struct thread *thread)
@@ -183,17 +201,23 @@ struct comm *thread__exec_comm(const struct thread *thread)
int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
bool exec)
{
- struct comm *new, *curr = thread__comm(thread);
+ struct comm *new, *curr;
+ int err = 0;
+
+ pthread_mutex_lock(&thread->comm_lock);
+ curr = thread__comm(thread);

/* Override the default :tid entry */
if (!thread->comm_set) {
- int err = comm__override(curr, str, timestamp, exec);
+ err = comm__override(curr, str, timestamp, exec);
if (err)
- return err;
+ goto unlock;
} else {
new = comm__new(str, timestamp, exec);
- if (!new)
- return -ENOMEM;
+ if (!new) {
+ err = -ENOMEM;
+ goto unlock;
+ }
list_add(&new->list, &thread->comm_list);

if (exec)
@@ -202,7 +226,9 @@ int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,

thread->comm_set = true;

- return 0;
+unlock:
+ pthread_mutex_unlock(&thread->comm_lock);
+ return err;
}

int thread__set_comm_from_proc(struct thread *thread)
@@ -222,14 +248,22 @@ int thread__set_comm_from_proc(struct thread *thread)
return err;
}

-const char *thread__comm_str(const struct thread *thread)
+const char *thread__comm_str(struct thread *thread)
{
- const struct comm *comm = thread__comm(thread);
+ const struct comm *comm;
+ const char *str;
+
+ pthread_mutex_lock(&thread->comm_lock);
+ comm = thread__comm(thread);

- if (!comm)
+ if (!comm) {
+ pthread_mutex_unlock(&thread->comm_lock);
return NULL;
+ }
+ str = comm__str(comm);

- return comm__str(comm);
+ pthread_mutex_unlock(&thread->comm_lock);
+ return str;
}

/* CHECKME: it should probably better return the max comm len from its comm list */
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index fd7bd41..1d3062a 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -29,7 +29,9 @@ struct thread {
int comm_len;
bool dead; /* if set thread has exited */
struct list_head namespaces_list;
+ pthread_mutex_t namespaces_lock;
struct list_head comm_list;
+ pthread_mutex_t comm_lock;
u64 db_id;

void *priv;
@@ -68,7 +70,7 @@ static inline void thread__exited(struct thread *thread)
struct namespaces *thread__namespaces(const struct thread *thread);
int thread__set_namespaces(struct thread *thread, u64 timestamp,
struct namespaces_event *event);
-void thread__namespaces_id(const struct thread *thread,
+void thread__namespaces_id(struct thread *thread,
u64 *dev, u64 *ino);

int __thread__set_comm(struct thread *thread, const char *comm, u64 timestamp,
@@ -84,7 +86,7 @@ int thread__set_comm_from_proc(struct thread *thread);
int thread__comm_len(struct thread *thread);
struct comm *thread__comm(const struct thread *thread);
struct comm *thread__exec_comm(const struct thread *thread);
-const char *thread__comm_str(const struct thread *thread);
+const char *thread__comm_str(struct thread *thread);
int thread__insert_map(struct thread *thread, struct map *map);
int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp);
size_t thread__fprintf(struct thread *thread, FILE *fp);
--
2.5.5
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