diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-09-29 02:00:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-29 09:18:17 -0700 |
| commit | 5fe1d75f34974046fffcca5e22fb8a7b42fded33 (patch) | |
| tree | 831e360aa8d7d37c7c5202937a2f617ebea6e737 /kernel/sched.c | |
| parent | c9472e0f28cd2f0695a0ac3a0b4bd33f21714a7e (diff) | |
[PATCH] do_sched_setscheduler(): don't take tasklist_lock
Use rcu locks instead. sched_setscheduler() now takes ->siglock
before reading ->signal->rlim[].
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index b946209d9c15..f9b3c6a414f1 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4080,6 +4080,8 @@ static void __setscheduler(struct task_struct *p, int policy, int prio) * @p: the task in question. * @policy: new policy. * @param: structure containing the new RT priority. + * + * NOTE: the task may be already dead */ int sched_setscheduler(struct task_struct *p, int policy, struct sched_param *param) @@ -4115,19 +4117,26 @@ recheck: * Allow unprivileged RT tasks to decrease priority: */ if (!capable(CAP_SYS_NICE)) { + unsigned long rlim_rtprio; + unsigned long flags; + + if (!lock_task_sighand(p, &flags)) + return -ESRCH; + rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur; + unlock_task_sighand(p, &flags); + /* * can't change policy, except between SCHED_NORMAL * and SCHED_BATCH: */ if (((policy != SCHED_NORMAL && p->policy != SCHED_BATCH) && (policy != SCHED_BATCH && p->policy != SCHED_NORMAL)) && - !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) + !rlim_rtprio) return -EPERM; /* can't increase priority */ if ((policy != SCHED_NORMAL && policy != SCHED_BATCH) && param->sched_priority > p->rt_priority && - param->sched_priority > - p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) + param->sched_priority > rlim_rtprio) return -EPERM; /* can't change other user's priorities */ if ((current->euid != p->euid) && @@ -4193,14 +4202,13 @@ do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) return -EINVAL; if (copy_from_user(&lparam, param, sizeof(struct sched_param))) return -EFAULT; - read_lock_irq(&tasklist_lock); + + rcu_read_lock(); + retval = -ESRCH; p = find_process_by_pid(pid); - if (!p) { - read_unlock_irq(&tasklist_lock); - return -ESRCH; - } - retval = sched_setscheduler(p, policy, &lparam); - read_unlock_irq(&tasklist_lock); + if (p != NULL) + retval = sched_setscheduler(p, policy, &lparam); + rcu_read_unlock(); return retval; } |