On Thu, 24 Feb 2011 14:58:58 +0800
Li Zefan <lizf@xxxxxxxxxxxxxx> wrote:
> Don't forget to release cgroup_mutex if alloc_trial_cpuset() fails.
>
> Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> ---
> kernel/cpuset.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index 1ca786a..6272503 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -1561,8 +1561,10 @@ static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
> return -ENODEV;
>
> trialcs = alloc_trial_cpuset(cs);
> - if (!trialcs)
> + if (!trialcs) {
> + cgroup_unlock();
> return -ENOMEM;
> + }
>
> switch (cft->private) {
> case FILE_CPULIST:
It would be better to avoid multiple returns - it leads to more
maintainable code and often shorter code:
--- a/kernel/cpuset.c~cpuset-add-a-missing-unlock-in-cpuset_write_resmask-fix
+++ a/kernel/cpuset.c
@@ -1562,8 +1562,8 @@ static int cpuset_write_resmask(struct c
trialcs = alloc_trial_cpuset(cs);
if (!trialcs) {
- cgroup_unlock();
- return -ENOMEM;
+ retval = -ENOMEM;
+ goto out;
}
switch (cft->private) {
@@ -1579,6 +1579,7 @@ static int cpuset_write_resmask(struct c
}
free_trial_cpuset(trialcs);
+out:
cgroup_unlock();
return retval;
}
_
also, alloc_trial_cpuset() is a fairly slow-looking function.
cpuset_write_resmask() could run alloc_trial_cpuset() before running
cgroup_lock_live_group(), thereby reducing lock hold times.
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