lkml.org 
[lkml]   [2009]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 3/6] cpuset: convert cpuset_attach() to use cpumask_var_t
    Andrew Morton wrote:
    > On Mon, 05 Jan 2009 16:47:21 +0800 Li Zefan <lizf@cn.fujitsu.com> wrote:
    >
    >> Allocate a global cpumask_var_t at boot, and use it in cpuset_attach(), so
    >> we won't fail cpuset_attach().
    >>
    >> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
    >> Acked-by: Mike Travis <travis@sgi.com>
    >> ---
    >> kernel/cpuset.c | 14 +++++++++-----
    >> 1 files changed, 9 insertions(+), 5 deletions(-)
    >>
    >> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
    >> index afa29cf..1e32e6b 100644
    >> --- a/kernel/cpuset.c
    >> +++ b/kernel/cpuset.c
    >> @@ -1306,6 +1306,9 @@ static int fmeter_getrate(struct fmeter *fmp)
    >> return val;
    >> }
    >>
    >> +/* 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)
    >> @@ -1330,7 +1333,6 @@ 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);
    >> @@ -1338,13 +1340,13 @@ 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;
    >>
    >> @@ -1357,7 +1359,6 @@ static void cpuset_attach(struct cgroup_subsys *ss,
    >> cpuset_migrate_mm(mm, &from, &to);
    >> mmput(mm);
    >> }
    >> -
    >> }
    >>
    >> /* The various types of files and directories in a cpuset file system */
    >> @@ -1838,6 +1839,9 @@ int __init cpuset_init(void)
    >> if (err < 0)
    >> return err;
    >>
    >> + if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
    >> + BUG();
    >> +
    >> number_of_cpusets = 1;
    >> return 0;
    >> }
    >
    > OK, that works.
    >
    > Do we need to dynamically allocate cpus_attach? Can we just do
    >
    > static cpumask_t cpus_attach;
    >
    > ?
    >

    Yes, it's used by cpuset_attach() only, and cpuset_attach() is called with
    cgroup_lock() held, so it won't happen that 2 threads access cpus_attach
    concurrently.



    \
     
     \ /
      Last update: 2009-01-05 10:09    [W:0.030 / U:1.160 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site