diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2009-12-09 10:14:58 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-12-14 17:11:34 +0100 |
| commit | 5fe85be081edf0ac92d83f9c39e0ab5c1371eb82 (patch) | |
| tree | 6c8d313aec92310787c14b7d289f69e3e5e38711 /kernel/sched.c | |
| parent | 663997d417330a59a566452f52cfa04c8ffd190b (diff) | |
| download | lwn-5fe85be081edf0ac92d83f9c39e0ab5c1371eb82.tar.gz lwn-5fe85be081edf0ac92d83f9c39e0ab5c1371eb82.zip | |
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/sched.c')
| -rw-r--r-- | kernel/sched.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 258c73c6a2f3..1782beed2fa7 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; } |