diff options
author | Oleg Nesterov <oleg@redhat.com> | 2010-05-26 17:43:24 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 12:12:47 -0400 |
commit | b3ac022cb9dc5883505a88b159d1b240ad1ef405 (patch) | |
tree | bffa035303cbe3c5bde048ac3d3154fb57059e2d | |
parent | dd98acf74762764fbc4382a1d9a244f11a2658cc (diff) |
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>
-rw-r--r-- | include/linux/init_task.h | 2 | ||||
-rw-r--r-- | include/linux/sched.h | 4 | ||||
-rw-r--r-- | kernel/exit.c | 5 | ||||
-rw-r--r-- | kernel/fork.c | 8 |
4 files changed, 8 insertions, 11 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; | |||
16 | extern struct fs_struct init_fs; | 16 | extern struct fs_struct init_fs; |
17 | 17 | ||
18 | #define INIT_SIGNALS(sig) { \ | 18 | #define INIT_SIGNALS(sig) { \ |
19 | .count = ATOMIC_INIT(1), \ | 19 | .nr_threads = 1, \ |
20 | .wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\ | 20 | .wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\ |
21 | .shared_pending = { \ | 21 | .shared_pending = { \ |
22 | .list = LIST_HEAD_INIT(sig.shared_pending.list), \ | 22 | .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 { | |||
527 | */ | 527 | */ |
528 | struct signal_struct { | 528 | struct signal_struct { |
529 | atomic_t sigcnt; | 529 | atomic_t sigcnt; |
530 | atomic_t count; | ||
531 | atomic_t live; | 530 | atomic_t live; |
531 | int nr_threads; | ||
532 | 532 | ||
533 | wait_queue_head_t wait_chldexit; /* for wait4() */ | 533 | wait_queue_head_t wait_chldexit; /* for wait4() */ |
534 | 534 | ||
@@ -2149,7 +2149,7 @@ extern bool current_is_single_threaded(void); | |||
2149 | 2149 | ||
2150 | static inline int get_nr_threads(struct task_struct *tsk) | 2150 | static inline int get_nr_threads(struct task_struct *tsk) |
2151 | { | 2151 | { |
2152 | return atomic_read(&tsk->signal->count); | 2152 | return tsk->signal->nr_threads; |
2153 | } | 2153 | } |
2154 | 2154 | ||
2155 | /* de_thread depends on thread_group_leader not being a pid based check */ | 2155 | /* de_thread depends on thread_group_leader not being a pid based check */ |
diff --git a/kernel/exit.c b/kernel/exit.c index 357d443d5a00..ceffc67b564a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c | |||
@@ -83,14 +83,10 @@ static void __exit_signal(struct task_struct *tsk) | |||
83 | struct sighand_struct *sighand; | 83 | struct sighand_struct *sighand; |
84 | struct tty_struct *uninitialized_var(tty); | 84 | struct tty_struct *uninitialized_var(tty); |
85 | 85 | ||
86 | BUG_ON(!sig); | ||
87 | BUG_ON(!atomic_read(&sig->count)); | ||
88 | |||
89 | sighand = rcu_dereference_check(tsk->sighand, | 86 | sighand = rcu_dereference_check(tsk->sighand, |
90 | rcu_read_lock_held() || | 87 | rcu_read_lock_held() || |
91 | lockdep_tasklist_lock_is_held()); | 88 | lockdep_tasklist_lock_is_held()); |
92 | spin_lock(&sighand->siglock); | 89 | spin_lock(&sighand->siglock); |
93 | atomic_dec(&sig->count); | ||
94 | 90 | ||
95 | posix_cpu_timers_exit(tsk); | 91 | posix_cpu_timers_exit(tsk); |
96 | if (group_dead) { | 92 | if (group_dead) { |
@@ -130,6 +126,7 @@ static void __exit_signal(struct task_struct *tsk) | |||
130 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; | 126 | sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
131 | } | 127 | } |
132 | 128 | ||
129 | sig->nr_threads--; | ||
133 | __unhash_process(tsk, group_dead); | 130 | __unhash_process(tsk, group_dead); |
134 | 131 | ||
135 | /* | 132 | /* |
diff --git a/kernel/fork.c b/kernel/fork.c index 40cd099cfc1b..d32410bd4be7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c | |||
@@ -877,9 +877,9 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) | |||
877 | if (!sig) | 877 | if (!sig) |
878 | return -ENOMEM; | 878 | return -ENOMEM; |
879 | 879 | ||
880 | atomic_set(&sig->sigcnt, 1); | 880 | sig->nr_threads = 1; |
881 | atomic_set(&sig->count, 1); | ||
882 | atomic_set(&sig->live, 1); | 881 | atomic_set(&sig->live, 1); |
882 | atomic_set(&sig->sigcnt, 1); | ||
883 | init_waitqueue_head(&sig->wait_chldexit); | 883 | init_waitqueue_head(&sig->wait_chldexit); |
884 | if (clone_flags & CLONE_NEWPID) | 884 | if (clone_flags & CLONE_NEWPID) |
885 | sig->flags |= SIGNAL_UNKILLABLE; | 885 | sig->flags |= SIGNAL_UNKILLABLE; |
@@ -1256,9 +1256,9 @@ static struct task_struct *copy_process(unsigned long clone_flags, | |||
1256 | } | 1256 | } |
1257 | 1257 | ||
1258 | if (clone_flags & CLONE_THREAD) { | 1258 | if (clone_flags & CLONE_THREAD) { |
1259 | atomic_inc(¤t->signal->sigcnt); | 1259 | current->signal->nr_threads++; |
1260 | atomic_inc(¤t->signal->count); | ||
1261 | atomic_inc(¤t->signal->live); | 1260 | atomic_inc(¤t->signal->live); |
1261 | atomic_inc(¤t->signal->sigcnt); | ||
1262 | p->group_leader = current->group_leader; | 1262 | p->group_leader = current->group_leader; |
1263 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); | 1263 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); |
1264 | } | 1264 | } |