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Biederman" , Jann Horn , Jens Axboe , Kees Cook , Linus Torvalds , Oleg Nesterov Subject: [RFC PATCH v3 1/8] Use refcount_t for ucounts reference counting Date: Fri, 15 Jan 2021 15:57:22 +0100 Message-Id: <116c7669744404364651e3b380db2d82bb23f983.1610722473.git.gladkov.alexey@gmail.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.1 (raptor.unsafe.ru [5.9.43.93]); Fri, 15 Jan 2021 14:59:10 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Signed-off-by: Alexey Gladkov --- include/linux/user_namespace.h | 2 +- kernel/ucount.c | 20 +++++++------------- 2 files changed, 8 insertions(+), 14 deletions(-) diff --git a/include/linux/user_namespace.h b/include/linux/user_namespac= e.h index 64cf8ebdc4ec..f84fc2d9ce20 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -92,7 +92,7 @@ struct ucounts { struct hlist_node node; struct user_namespace *ns; kuid_t uid; - int count; + refcount_t count; atomic_t ucount[UCOUNT_COUNTS]; }; =20 diff --git a/kernel/ucount.c b/kernel/ucount.c index 11b1596e2542..82acd2226460 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -141,7 +141,8 @@ static struct ucounts *get_ucounts(struct user_namesp= ace *ns, kuid_t uid) =20 new->ns =3D ns; new->uid =3D uid; - new->count =3D 0; + + refcount_set(&new->count, 0); =20 spin_lock_irq(&ucounts_lock); ucounts =3D find_ucounts(ns, uid, hashent); @@ -152,10 +153,7 @@ static struct ucounts *get_ucounts(struct user_names= pace *ns, kuid_t uid) ucounts =3D new; } } - if (ucounts->count =3D=3D INT_MAX) - ucounts =3D NULL; - else - ucounts->count +=3D 1; + refcount_inc(&ucounts->count); spin_unlock_irq(&ucounts_lock); return ucounts; } @@ -164,15 +162,11 @@ static void put_ucounts(struct ucounts *ucounts) { unsigned long flags; =20 - spin_lock_irqsave(&ucounts_lock, flags); - ucounts->count -=3D 1; - if (!ucounts->count) + if (refcount_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, &flag= s)) { hlist_del_init(&ucounts->node); - else - ucounts =3D NULL; - spin_unlock_irqrestore(&ucounts_lock, flags); - - kfree(ucounts); + spin_unlock_irqrestore(&ucounts_lock, flags); + kfree(ucounts); + } } =20 static inline bool atomic_inc_below(atomic_t *v, int u) --=20 2.29.2