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| author |   Thomas Gleixner <tglx@linutronix.de> | 2009-12-09 10:15:01 +0000 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2009-12-14 17:11:35 +0100 |
| commit | 23f5d142519621b16cf2b378cf8adf4dcf01a616 (patch) | |
| tree | c7907cb635ea1ad6cab71598d687b752c17adf37 /kernel/sched.c | |
| parent | sched: Use rcu in sys_sched_getscheduler/sys_sched_getparam() (diff) | |
| download | linux-dev-23f5d142519621b16cf2b378cf8adf4dcf01a616.tar.xz linux-dev-23f5d142519621b16cf2b378cf8adf4dcf01a616.zip | |
sched: Use rcu in sched_get/set_affinity()
tasklist_lock is held read locked to protect the
find_task_by_vpid() call and to prevent the task going away.
sched_setaffinity acquires a task struct ref and drops tasklist
lock right away. The access to the cpus_allowed mask is
protected by rq->lock.
rcu_read_lock() provides the same protection here.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091209100706.789059966@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 1782beed2fa7..79893123325c 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6516,22 +6516,18 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) int retval; get_online_cpus(); - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_process_by_pid(pid); if (!p) { - read_unlock(&tasklist_lock); + rcu_read_unlock(); put_online_cpus(); return -ESRCH; } - /* - * It is not safe to call set_cpus_allowed with the - * tasklist_lock held. We will bump the task_struct's - * usage count and then drop tasklist_lock. - */ + /* Prevent p going away */ get_task_struct(p); - read_unlock(&tasklist_lock); + rcu_read_unlock(); if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { retval = -ENOMEM; @@ -6617,7 +6613,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask) int retval; get_online_cpus(); - read_lock(&tasklist_lock); + rcu_read_lock(); retval = -ESRCH; p = find_process_by_pid(pid); @@ -6633,7 +6629,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask) task_rq_unlock(rq, &flags); out_unlock: - read_unlock(&tasklist_lock); + rcu_read_unlock(); put_online_cpus(); return retval; |