diff options
| author | Aleksa Sarai <cyphar@cyphar.com> | 2019-10-17 02:50:01 +1100 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2019-10-24 12:07:10 -0700 |
| commit | a713af394cf382a30dd28a1015cbe572f1b9ca75 (patch) | |
| tree | be789f59b00a4a4a2bcbcdf3fd571f606e3cf1e2 | |
| parent | 1a99fcc035fb666f5d0909aef0a753284cb5d04c (diff) | |
cgroup: pids: use atomic64_t for pids->limit
Because pids->limit can be changed concurrently (but we don't want to
take a lock because it would be needlessly expensive), use atomic64_ts
instead.
Fixes: commit 49b786ea146f ("cgroup: implement the PIDs subsystem")
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | kernel/cgroup/pids.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c index 8e513a573fe9..138059eb730d 100644 --- a/kernel/cgroup/pids.c +++ b/kernel/cgroup/pids.c @@ -45,7 +45,7 @@ struct pids_cgroup { * %PIDS_MAX = (%PID_MAX_LIMIT + 1). */ atomic64_t counter; - int64_t limit; + atomic64_t limit; /* Handle for "pids.events" */ struct cgroup_file events_file; @@ -73,8 +73,8 @@ pids_css_alloc(struct cgroup_subsys_state *parent) if (!pids) return ERR_PTR(-ENOMEM); - pids->limit = PIDS_MAX; atomic64_set(&pids->counter, 0); + atomic64_set(&pids->limit, PIDS_MAX); atomic64_set(&pids->events_limit, 0); return &pids->css; } @@ -146,13 +146,14 @@ static int pids_try_charge(struct pids_cgroup *pids, int num) for (p = pids; parent_pids(p); p = parent_pids(p)) { int64_t new = atomic64_add_return(num, &p->counter); + int64_t limit = atomic64_read(&p->limit); /* * Since new is capped to the maximum number of pid_t, if * p->limit is %PIDS_MAX then we know that this test will never * fail. */ - if (new > p->limit) + if (new > limit) goto revert; } @@ -277,7 +278,7 @@ set_limit: * Limit updates don't need to be mutex'd, since it isn't * critical that any racing fork()s follow the new limit. */ - pids->limit = limit; + atomic64_set(&pids->limit, limit); return nbytes; } @@ -285,7 +286,7 @@ static int pids_max_show(struct seq_file *sf, void *v) { struct cgroup_subsys_state *css = seq_css(sf); struct pids_cgroup *pids = css_pids(css); - int64_t limit = pids->limit; + int64_t limit = atomic64_read(&pids->limit); if (limit >= PIDS_MAX) seq_printf(sf, "%s\n", PIDS_MAX_STR); |