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| author | Eric W. Biederman <ebiederm@xmission.com> | 2021-10-16 14:05:34 -0500 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2021-10-20 10:45:34 -0500 |
| commit | da70d3109e74adf6ae9f8d1f6c7c0c9735d314ba (patch) | |
| tree | dd7eb1eef0114f31f39de85906ad9ebae955fe37 /kernel/ucount.c | |
| parent | 5fc9e37cd5ae762b856912cdedb226a884b3c3e0 (diff) | |
| download | linux-da70d3109e74adf6ae9f8d1f6c7c0c9735d314ba.tar.bz2 | |
ucounts: Add get_ucounts_or_wrap for clarity
Add a helper function get_ucounts_or_wrap that is a trivial
wrapper around atomic_add_negative, that makes it clear
how atomic_add_negative is used in the context of ucounts.
Link: https://lkml.kernel.org/r/87pms2qkr9.fsf_-_@disp2133
Tested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/ucount.c')
| -rw-r--r-- | kernel/ucount.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/kernel/ucount.c b/kernel/ucount.c index 708d05164a7d..133b6044fda4 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 (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; } |