From 71184089b8ce5e46cc5377962e04f885b86e9cbd Mon Sep 17 00:00:00 2001 From: Pavankumar Kondeti Date: Wed, 21 Jun 2017 09:22:45 +0530 Subject: [PATCH] ANDROID: uid_sys_stats: Replace tasklist lock with RCU in uid_cputime_show Tasklist lock is acuquired in uid_cputime_show for updating the stats for all tasks in the system. This can potentially disable preemption for several milli seconds. Replace tasklist_lock with RCU read side primitives. Change-Id: Ife69cb577bfdceaae6eb21b9bda09a0fe687e140 Signed-off-by: Pavankumar Kondeti --- drivers/misc/uid_sys_stats.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/misc/uid_sys_stats.c b/drivers/misc/uid_sys_stats.c index 0014ad5..a940f97 100644 --- a/drivers/misc/uid_sys_stats.c +++ b/drivers/misc/uid_sys_stats.c @@ -346,13 +346,13 @@ static int uid_cputime_show(struct seq_file *m, void *v) uid_entry->active_utime = 0; } - read_lock(&tasklist_lock); + rcu_read_lock(); do_each_thread(temp, task) { uid = from_kuid_munged(user_ns, task_uid(task)); if (!uid_entry || uid_entry->uid != uid) uid_entry = find_or_register_uid(uid); if (!uid_entry) { - read_unlock(&tasklist_lock); + rcu_read_unlock(); rt_mutex_unlock(&uid_lock); pr_err("%s: failed to find the uid_entry for uid %d\n", __func__, uid); @@ -362,7 +362,7 @@ static int uid_cputime_show(struct seq_file *m, void *v) uid_entry->active_utime += utime; uid_entry->active_stime += stime; } while_each_thread(temp, task); - read_unlock(&tasklist_lock); + rcu_read_unlock(); hash_for_each(hash_table, bkt, uid_entry, hash) { cputime_t total_utime = uid_entry->utime + -- 2.7.4