diff options
| -rw-r--r-- | kernel/cred.c | 5 | ||||
| -rw-r--r-- | kernel/ucount.c | 20 |
2 files changed, 15 insertions, 10 deletions
diff --git a/kernel/cred.c b/kernel/cred.c index 1ae0b4948a5a..473d17c431f3 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -676,15 +676,14 @@ int set_cred_ucounts(struct cred *new) * This optimization is needed because alloc_ucounts() uses locks * for table lookups. */ - if (old_ucounts && old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid)) + if (old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid)) return 0; if (!(new_ucounts = alloc_ucounts(new->user_ns, new->euid))) return -EAGAIN; new->ucounts = new_ucounts; - if (old_ucounts) - put_ucounts(old_ucounts); + put_ucounts(old_ucounts); return 0; } diff --git a/kernel/ucount.c b/kernel/ucount.c index eb03f3c68375..4f5613dac227 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -150,9 +150,15 @@ static void hlist_add_ucounts(struct ucounts *ucounts) spin_unlock_irq(&ucounts_lock); } +static inline bool get_ucounts_or_wrap(struct ucounts *ucounts) +{ + /* Returns true on a successful get, false if the count wraps. */ + return !atomic_add_negative(1, &ucounts->count); +} + struct ucounts *get_ucounts(struct ucounts *ucounts) { - if (ucounts && atomic_add_negative(1, &ucounts->count)) { + if (!get_ucounts_or_wrap(ucounts)) { put_ucounts(ucounts); ucounts = NULL; } @@ -163,7 +169,7 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) { struct hlist_head *hashent = ucounts_hashentry(ns, uid); struct ucounts *ucounts, *new; - long overflow; + bool wrapped; spin_lock_irq(&ucounts_lock); ucounts = find_ucounts(ns, uid, hashent); @@ -188,9 +194,9 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) return new; } } - overflow = atomic_add_negative(1, &ucounts->count); + wrapped = !get_ucounts_or_wrap(ucounts); spin_unlock_irq(&ucounts_lock); - if (overflow) { + if (wrapped) { put_ucounts(ucounts); return NULL; } @@ -276,7 +282,7 @@ bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v) struct ucounts *iter; long new = -1; /* Silence compiler warning */ for (iter = ucounts; iter; iter = iter->ns->ucounts) { - long dec = atomic_long_add_return(-v, &iter->ucount[type]); + long dec = atomic_long_sub_return(v, &iter->ucount[type]); WARN_ON_ONCE(dec < 0); if (iter == ucounts) new = dec; @@ -289,7 +295,7 @@ static void do_dec_rlimit_put_ucounts(struct ucounts *ucounts, { struct ucounts *iter, *next; for (iter = ucounts; iter != last; iter = next) { - long dec = atomic_long_add_return(-1, &iter->ucount[type]); + long dec = atomic_long_sub_return(1, &iter->ucount[type]); WARN_ON_ONCE(dec < 0); next = iter->ns->ucounts; if (dec == 0) @@ -326,7 +332,7 @@ long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum ucount_type type) } return ret; dec_unwind: - dec = atomic_long_add_return(-1, &iter->ucount[type]); + dec = atomic_long_sub_return(1, &iter->ucount[type]); WARN_ON_ONCE(dec < 0); unwind: do_dec_rlimit_put_ucounts(ucounts, iter, type); |