diff options
author | Otavio Salvador <otavio@ossystems.com.br> | 2020-05-20 08:43:03 -0300 |
---|---|---|
committer | GitHub <noreply@github.com> | 2020-05-20 08:43:03 -0300 |
commit | 1279cd128bba968ebe0a2df7f7ae38bae90250ef (patch) | |
tree | df6b1a190760f51465122ca4c13492d5ac5984c6 /kernel/taskstats.c | |
parent | 0a8ab17689e628c84a666195bfc6ab85d11cf057 (diff) | |
parent | 2ae782ca839e0ee07de37122ddea362adff2e975 (diff) |
Merge pull request #76 from toradex/4.9-2.3.x-imx
4.9 2.3.x imx
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 cbb387a265db..23df1fbad4b4 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -559,25 +559,33 @@ 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 */ |