[PATCH 07/13] proc: convert /proc/thread-self to _print_integer()

[Alexey Dobriyan]

Benchmark readlink("/proc/thread-self") 2^23 times:

        9.447948508 seconds time elapsed ( +-  0.06% )
        7.846435274 seconds time elapsed ( +-  0.07% )

        -17%
---
 fs/proc/thread_self.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index b905010ca9eb..03dd644d8ada 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -15,6 +15,7 @@ static const char *proc_thread_self_get_link(struct dentry 
*dentry,
        struct pid_namespace *ns = proc_pid_ns(inode);
        pid_t tgid = task_tgid_nr_ns(current, ns);
        pid_t pid = task_pid_nr_ns(current, ns);
+       char buf[10 + 6 + 10], *p = buf + sizeof(buf);
        char *name;
 
        if (!pid)
@@ -22,7 +23,13 @@ static const char *proc_thread_self_get_link(struct dentry 
*dentry,
        name = kmalloc(10 + 6 + 10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);
        if (unlikely(!name))
                return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
-       sprintf(name, "%u/task/%u", tgid, pid);
+
+       p = _print_integer_u32(p, pid);
+       p = memcpy(p - 6, "/task/", 6);
+       p = _print_integer_u32(p, tgid);
+       memcpy(name, p, buf + sizeof(buf) - p);
+       name[buf + sizeof(buf) - p] = '\0';
+
        set_delayed_call(done, kfree_link, name);
        return name;
 }
-- 
2.16.4