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authorThomas Gleixner <tglx@linutronix.de>2009-12-09 10:14:58 +0000
committerIngo Molnar <mingo@elte.hu>2009-12-14 17:11:34 +0100
commit5fe85be081edf0ac92d83f9c39e0ab5c1371eb82 (patch)
tree6c8d313aec92310787c14b7d289f69e3e5e38711 /kernel
parent663997d417330a59a566452f52cfa04c8ffd190b (diff)
downloadop-kernel-dev-5fe85be081edf0ac92d83f9c39e0ab5c1371eb82.zip
op-kernel-dev-5fe85be081edf0ac92d83f9c39e0ab5c1371eb82.tar.gz
sched: Use rcu in sys_sched_getscheduler/sys_sched_getparam()
read_lock(&tasklist_lock) does not protect sys_sched_getscheduler and sys_sched_getparam() against a concurrent update of the policy or scheduler parameters as do_sched_setscheduler() does not take the tasklist_lock. The accessed integers can be retrieved w/o locking and are snapshots anyway. Using rcu_read_lock() to protect find_task_by_vpid() and prevent the task struct from going away is not changing the above situation. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <20091209100706.753790977@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 258c73c..1782bee 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6458,7 +6458,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
return -EINVAL;
retval = -ESRCH;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_process_by_pid(pid);
if (p) {
retval = security_task_getscheduler(p);
@@ -6466,7 +6466,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
retval = p->policy
| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
}
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return retval;
}
@@ -6484,7 +6484,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
if (!param || pid < 0)
return -EINVAL;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_process_by_pid(pid);
retval = -ESRCH;
if (!p)
@@ -6495,7 +6495,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
goto out_unlock;
lp.sched_priority = p->rt_priority;
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
/*
* This one might sleep, we cannot do it with a spinlock held ...
@@ -6505,7 +6505,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
return retval;
out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return retval;
}
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