Messages in this thread Patch in this message | | | Date | Wed, 31 Dec 2008 16:36:11 +0800 | From | Li Zefan <> | Subject | [PATCH 3/6] cpuset: convert cpuset_attach() to use cpumask_var_t |
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Impact: reduce stack usage
Allocate a cpumask_var_t in cpuset_can_attach() and then use it in cpuset_attach(), so we won't fail cpuset_attach().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> --- kernel/cpuset.c | 31 +++++++++++++++++++++++++------ 1 files changed, 25 insertions(+), 6 deletions(-)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index afa29cf..b4c36d5 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1306,6 +1306,14 @@ static int fmeter_getrate(struct fmeter *fmp) return val; } +/* + * Since cpuset_attach() can't fail, we allocate a cpumask_var_t in + * cpuset_can_attach() and then use it in cpuset_attach(). + * + * Protected by cgroup_lock. + */ +static cpumask_var_t cpus_attach; + /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct task_struct *tsk) @@ -1321,16 +1329,25 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, if (!cpus_equal(tsk->cpus_allowed, cs->cpus_allowed)) ret = -EINVAL; mutex_unlock(&callback_mutex); + + if (ret) + return ret; } - return ret < 0 ? ret : security_task_setscheduler(tsk, 0, NULL); + ret = security_task_setscheduler(tsk, 0, NULL); + if (ret) + return ret; + + if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL)) + return -ENOMEM; + + return 0; } static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct cgroup *oldcont, struct task_struct *tsk) { - cpumask_t cpus; nodemask_t from, to; struct mm_struct *mm; struct cpuset *cs = cgroup_cs(cont); @@ -1338,15 +1355,15 @@ static void cpuset_attach(struct cgroup_subsys *ss, int err; if (cs == &top_cpuset) { - cpus = cpu_possible_map; + cpumask_copy(cpus_attach, cpu_possible_mask); } else { mutex_lock(&callback_mutex); - guarantee_online_cpus(cs, &cpus); + guarantee_online_cpus(cs, cpus_attach); mutex_unlock(&callback_mutex); } - err = set_cpus_allowed_ptr(tsk, &cpus); + err = set_cpus_allowed_ptr(tsk, cpus_attach); if (err) - return; + goto out; from = oldcs->mems_allowed; to = cs->mems_allowed; @@ -1358,6 +1375,8 @@ static void cpuset_attach(struct cgroup_subsys *ss, mmput(mm); } +out: + free_cpumask_var(cpus_attach); } /* The various types of files and directories in a cpuset file system */ -- 1.5.4.rc3
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