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ANDROID: uid_sys_stats: Replace tasklist lock with RCU in uid_cputime_show

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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 <pkondeti@codeaurora.org>
This commit is contained in:
Pavankumar Kondeti 2017-06-21 09:22:45 +05:30 committed by Amit Pundir
parent b8ab1e4c0d
commit aab728ca5f
1 changed files with 3 additions and 3 deletions
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6
drivers/misc/uid_sys_stats.c
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@ -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) {
u64 total_utime = uid_entry->utime +