diff options
| author | Dave Airlie <airlied@redhat.com> | 2020-01-20 11:08:11 +1000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2020-01-20 11:42:57 +1000 |
| commit | 3d4743131b8de970faa4b979ead0fadfe5d2de9d (patch) | |
| tree | 68e948c2d94d48598dd37e31bb654feb0b43ae4a /kernel/taskstats.c | |
| parent | df95968ff78931576ac7a3d3b30312894aaaf22e (diff) | |
| parent | def9d2780727cec3313ed3522d0123158d87224d (diff) | |
Backmerge v5.5-rc7 into drm-next
msm needs 5.5-rc4, go to the latest.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'kernel/taskstats.c')
| -rw-r--r-- | kernel/taskstats.c | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/kernel/taskstats.c b/kernel/taskstats.c index 13a0f2e6ebc2..e2ac0e37c4ae 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -554,25 +554,33 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info) static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk) { struct signal_struct *sig = tsk->signal; - struct taskstats *stats; + struct taskstats *stats_new, *stats; - if (sig->stats || thread_group_empty(tsk)) - goto ret; + /* Pairs with smp_store_release() below. */ + stats = smp_load_acquire(&sig->stats); + if (stats || thread_group_empty(tsk)) + return stats; /* No problem if kmem_cache_zalloc() fails */ - stats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL); + stats_new = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL); spin_lock_irq(&tsk->sighand->siglock); - if (!sig->stats) { - sig->stats = stats; - stats = NULL; + stats = sig->stats; + if (!stats) { + /* + * Pairs with smp_store_release() above and order the + * kmem_cache_zalloc(). + */ + smp_store_release(&sig->stats, stats_new); + stats = stats_new; + stats_new = NULL; } spin_unlock_irq(&tsk->sighand->siglock); - if (stats) - kmem_cache_free(taskstats_cache, stats); -ret: - return sig->stats; + if (stats_new) + kmem_cache_free(taskstats_cache, stats_new); + + return stats; } /* Send pid data out on exit */ |