[PATCH -mm 1/3] proc: get_nr_threads() doesn't need ->siglock any longer
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From: Oleg Nesterov on 22 Mar 2010 14:50 Now that task->signal can't go away get_nr_threads() doesn't need ->siglock to read signal->count. Also, make it inline, move into sched.h, and convert 2 other proc users of signal->count to use this (now trivial) helper. Henceforth get_nr_threads() is the only valid user of signal->count, we are ready to turn it into "int nr_threads" or, perhaps, kill it. Signed-off-by: Oleg Nesterov <oleg(a)redhat.com> --- include/linux/sched.h | 5 +++++ fs/proc/array.c | 4 ++-- fs/proc/base.c | 12 ------------ 3 files changed, 7 insertions(+), 14 deletions(-) --- 34-rc1/include/linux/sched.h~PROC_1_GNT_DONT_USE_SIGLOCK 2010-03-22 16:35:43.000000000 +0100 +++ 34-rc1/include/linux/sched.h 2010-03-22 16:41:53.000000000 +0100 @@ -2148,6 +2148,11 @@ extern bool current_is_single_threaded(v #define while_each_thread(g, t) \ while ((t = next_thread(t)) != g) +static inline int get_nr_threads(struct task_struct *tsk) +{ + return atomic_read(&tsk->signal->count); +} + /* de_thread depends on thread_group_leader not being a pid based check */ #define thread_group_leader(p) (p == p->group_leader) --- 34-rc1/fs/proc/array.c~PROC_1_GNT_DONT_USE_SIGLOCK 2010-03-11 13:11:50.000000000 +0100 +++ 34-rc1/fs/proc/array.c 2010-03-22 17:04:44.000000000 +0100 @@ -269,7 +269,7 @@ static inline void task_sig(struct seq_f shpending = p->signal->shared_pending.signal; blocked = p->blocked; collect_sigign_sigcatch(p, &ignored, &caught); - num_threads = atomic_read(&p->signal->count); + num_threads = get_nr_threads(p); rcu_read_lock(); /* FIXME: is this correct? */ qsize = atomic_read(&__task_cred(p)->user->sigpending); rcu_read_unlock(); @@ -412,7 +412,7 @@ static int do_task_stat(struct seq_file tty_nr = new_encode_dev(tty_devnum(sig->tty)); } - num_threads = atomic_read(&sig->count); + num_threads = get_nr_threads(task); collect_sigign_sigcatch(task, &sigign, &sigcatch); cmin_flt = sig->cmin_flt; --- 34-rc1/fs/proc/base.c~PROC_1_GNT_DONT_USE_SIGLOCK 2010-03-22 16:35:43.000000000 +0100 +++ 34-rc1/fs/proc/base.c 2010-03-22 16:36:28.000000000 +0100 @@ -165,18 +165,6 @@ static int get_fs_path(struct task_struc return result; } -static int get_nr_threads(struct task_struct *tsk) -{ - unsigned long flags; - int count = 0; - - if (lock_task_sighand(tsk, &flags)) { - count = atomic_read(&tsk->signal->count); - unlock_task_sighand(tsk, &flags); - } - return count; -} - static int proc_cwd_link(struct inode *inode, struct path *path) { struct task_struct *task = get_proc_task(inode); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |