| Message ID | 447547b12bba1894d3f1f79d6408dfc60b219b0c.1610299857.git.gladkov.alexey@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Count rlimits in each user namespace | expand |
Alexey Gladkov <gladkov.alexey@gmail.com> writes: We might want to use refcount_t instead of atomic_t. Not a big deal either way. > Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com> > --- > include/linux/user_namespace.h | 2 +- > kernel/ucount.c | 10 +++++----- > 2 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h > index 64cf8ebdc4ec..84fefa9247c4 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; > + atomic_t count; > atomic_t ucount[UCOUNT_COUNTS]; > }; > > diff --git a/kernel/ucount.c b/kernel/ucount.c > index 11b1596e2542..0f2c7c11df19 100644 > --- a/kernel/ucount.c > +++ b/kernel/ucount.c > @@ -141,7 +141,8 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid) > > new->ns = ns; > new->uid = uid; > - new->count = 0; > + > + atomic_set(&new->count, 0); > > spin_lock_irq(&ucounts_lock); > ucounts = find_ucounts(ns, uid, hashent); > @@ -152,10 +153,10 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid) > ucounts = new; > } > } > - if (ucounts->count == INT_MAX) > + if (atomic_read(&ucounts->count) == INT_MAX) > ucounts = NULL; > else > - ucounts->count += 1; > + atomic_inc(&ucounts->count); > spin_unlock_irq(&ucounts_lock); > return ucounts; > } > @@ -165,8 +166,7 @@ static void put_ucounts(struct ucounts *ucounts) > unsigned long flags; > > spin_lock_irqsave(&ucounts_lock, flags); > - ucounts->count -= 1; > - if (!ucounts->count) > + if (atomic_dec_and_test(&ucounts->count)) > hlist_del_init(&ucounts->node); > else > ucounts = NULL; This can become: static void put_ucounts(struct ucounts *ucounts) { unsigned long flags; if (atomic_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, flags)) { hlist_del_init(&ucounts->node); spin_unlock_irqrestore(&ucounts_lock); kfree(ucounts); } }
On Wed, Jan 13, 2021 at 10:31:40AM -0600, Eric W. Biederman wrote: > Alexey Gladkov <gladkov.alexey@gmail.com> writes: > > We might want to use refcount_t instead of atomic_t. Not a big deal > either way. Yes, please use refcount_t, and don't use _read() since that introduces races. -Kees > > > Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com> > > --- > > include/linux/user_namespace.h | 2 +- > > kernel/ucount.c | 10 +++++----- > > 2 files changed, 6 insertions(+), 6 deletions(-) > > > > diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h > > index 64cf8ebdc4ec..84fefa9247c4 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; > > + atomic_t count; > > atomic_t ucount[UCOUNT_COUNTS]; > > }; > > > > diff --git a/kernel/ucount.c b/kernel/ucount.c > > index 11b1596e2542..0f2c7c11df19 100644 > > --- a/kernel/ucount.c > > +++ b/kernel/ucount.c > > @@ -141,7 +141,8 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid) > > > > new->ns = ns; > > new->uid = uid; > > - new->count = 0; > > + > > + atomic_set(&new->count, 0); > > > > spin_lock_irq(&ucounts_lock); > > ucounts = find_ucounts(ns, uid, hashent); > > @@ -152,10 +153,10 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid) > > ucounts = new; > > } > > } > > - if (ucounts->count == INT_MAX) > > + if (atomic_read(&ucounts->count) == INT_MAX) > > ucounts = NULL; > > else > > - ucounts->count += 1; > > + atomic_inc(&ucounts->count); > > spin_unlock_irq(&ucounts_lock); > > return ucounts; > > } > > @@ -165,8 +166,7 @@ static void put_ucounts(struct ucounts *ucounts) > > unsigned long flags; > > > > spin_lock_irqsave(&ucounts_lock, flags); > > - ucounts->count -= 1; > > - if (!ucounts->count) > > + if (atomic_dec_and_test(&ucounts->count)) > > hlist_del_init(&ucounts->node); > > else > > ucounts = NULL; > > > This can become: > static void put_ucounts(struct ucounts *ucounts) > { > unsigned long flags; > > if (atomic_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, flags)) { > hlist_del_init(&ucounts->node); > spin_unlock_irqrestore(&ucounts_lock); > kfree(ucounts); > } > } >
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 64cf8ebdc4ec..84fefa9247c4 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; + atomic_t count; atomic_t ucount[UCOUNT_COUNTS]; }; diff --git a/kernel/ucount.c b/kernel/ucount.c index 11b1596e2542..0f2c7c11df19 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -141,7 +141,8 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid) new->ns = ns; new->uid = uid; - new->count = 0; + + atomic_set(&new->count, 0); spin_lock_irq(&ucounts_lock); ucounts = find_ucounts(ns, uid, hashent); @@ -152,10 +153,10 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid) ucounts = new; } } - if (ucounts->count == INT_MAX) + if (atomic_read(&ucounts->count) == INT_MAX) ucounts = NULL; else - ucounts->count += 1; + atomic_inc(&ucounts->count); spin_unlock_irq(&ucounts_lock); return ucounts; } @@ -165,8 +166,7 @@ static void put_ucounts(struct ucounts *ucounts) unsigned long flags; spin_lock_irqsave(&ucounts_lock, flags); - ucounts->count -= 1; - if (!ucounts->count) + if (atomic_dec_and_test(&ucounts->count)) hlist_del_init(&ucounts->node); else ucounts = NULL;
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com> --- include/linux/user_namespace.h | 2 +- kernel/ucount.c | 10 +++++----- 2 files changed, 6 insertions(+), 6 deletions(-)