Messages in this thread Patch in this message |  | | | From | Jiri Slaby <> | | Subject | [PATCH v2 7/8] core: optimize setrlimit for current task | | Date | Thu, 3 Sep 2009 22:08:43 +0200 |
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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 <jirislaby@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> --- kernel/sys.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index 791b5c5..feca9d6 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1247,11 +1247,14 @@ int setrlimit(struct task_struct *tsk, unsigned int resource, 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); @@ -1291,7 +1294,8 @@ int setrlimit(struct task_struct *tsk, unsigned int resource, update_rlimit_cpu(tsk, new_rlim->rlim_cur); out: - read_unlock(&tasklist_lock); + if (tsk != current) + read_unlock(&tasklist_lock); return retval; } -- 1.6.3.3
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