From d54c730eba63dfe0dcb8c7ab41514c564c159212 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Fri, 28 Aug 2009 14:08:17 +0200 Subject: [PATCH] core: optimize setrlimit for current task References: FATE#305733 Patch-mainline: no (later) Don't take tasklist lock for 'current'. It's not needed, since current->sighand/signal can't disappear. This improves serlimit called especially via sys_setrlimit. Signed-off-by: Jiri Slaby Cc: Oleg Nesterov --- kernel/sys.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1316,11 +1316,14 @@ int do_setrlimit(struct task_struct *tsk if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open) return -EPERM; - /* protect tsk->signal and tsk->sighand from disappearing */ - read_lock(&tasklist_lock); - if (!tsk->sighand) { - retval = -ESRCH; - goto out; + /* optimization: 'current' doesn't need locking, e.g. setrlimit */ + if (tsk != current) { + /* protect tsk->signal and tsk->sighand from disappearing */ + read_lock(&tasklist_lock); + if (!tsk->sighand) { + retval = -ESRCH; + goto out; + } } retval = security_task_setrlimit(tsk, resource, new_rlim); @@ -1360,7 +1363,8 @@ int do_setrlimit(struct task_struct *tsk update_rlimit_cpu(tsk, new_rlim->rlim_cur); out: - read_unlock(&tasklist_lock); + if (tsk != current) + read_unlock(&tasklist_lock); return retval; }