proc: turn signal_struct->count into "int nr_threads"

No functional changes, just s/atomic_t count/int nr_threads/.

With the recent changes this counter has a single user, get_nr_threads()
And, none of its callers need the really accurate number of threads, not
to mention each caller obviously races with fork/exit.  It is only used to
report this value to the user-space, except first_tid() uses it to avoid
the unnecessary while_each_thread() loop in the unlikely case.

It is a bit sad we need a word in struct signal_struct for this, perhaps
we can change get_nr_threads() to approximate the number of threads using
signal->live and kill ->nr_threads later.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 3 deletions

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 7996fc2c9ba9..0551e0dcb71b 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -16,7 +16,7 @@ extern struct files_struct init_files;
 extern struct fs_struct init_fs;
 
 #define INIT_SIGNALS(sig) {                                             \
-        .count          = ATOMIC_INIT(1),                               \
+        .nr_threads     = 1,                                            \
         .wait_chldexit  = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\
         .shared_pending = {                                             \
                 .list = LIST_HEAD_INIT(sig.shared_pending.list),        \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ccd2d1500720..f118809c953f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -527,8 +527,8 @@ struct thread_group_cputimer {
  */
 struct signal_struct {
         atomic_t                sigcnt;
-        atomic_t                count;
         atomic_t                live;
+        int                     nr_threads;
 
         wait_queue_head_t       wait_chldexit;  /* for wait4() */
 
@@ -2149,7 +2149,7 @@ extern bool current_is_single_threaded(void);
 
 static inline int get_nr_threads(struct task_struct *tsk)
 {
-        return atomic_read(&tsk->signal->count);
+        return tsk->signal->nr_threads;
 }
 
 /* de_thread depends on thread_group_leader not being a pid based check */