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Date: Wed, 30 Sep 2015 22:49:20 +0200
From: Rasmus Villemoes <linux@...musvillemoes.dk>
To: "Eric W. Biederman" <ebiederm@...ssion.com>,
Oleg Nesterov <oleg@...hat.com>
Cc: Rasmus Villemoes <linux@...musvillemoes.dk>,
linux-kernel@...r.kernel.org
Subject: [RFC 1/4] pid_namespace: remove ->level and ->parent for !CONFIG_PID_NS
When !CONFIG_PID_NS, there is only ever one struct pid_namespace, and
for that we know that ->parent is NULL and ->level is 0. Telling the
compiler that allows it to generate slightly smaller code.
Removing the members from struct pid_namespace only saves a few bytes,
but it also helps ensure that everyone outside kernel/pid_namespace.c
use the new accessors pid_ns_{parent,level}.
Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
include/linux/pid_namespace.h | 18 ++++++++++++++++++
kernel/acct.c | 4 ++--
kernel/pid.c | 18 +++++++++---------
3 files changed, 29 insertions(+), 11 deletions(-)
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 918b117a7cd3..03a84a0cdc75 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -29,8 +29,10 @@ struct pid_namespace {
unsigned int nr_hashed;
struct task_struct *child_reaper;
struct kmem_cache *pid_cachep;
+#ifdef CONFIG_PID_NS
unsigned int level;
struct pid_namespace *parent;
+#endif
#ifdef CONFIG_PROC_FS
struct vfsmount *proc_mnt;
struct dentry *proc_self;
@@ -58,6 +60,14 @@ static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
kref_get(&ns->kref);
return ns;
}
+static inline struct pid_namespace *pid_ns_parent(struct pid_namespace *ns)
+{
+ return ns->parent;
+}
+static inline int pid_ns_level(struct pid_namespace *ns)
+{
+ return ns->level;
+}
extern struct pid_namespace *copy_pid_ns(unsigned long flags,
struct user_namespace *user_ns, struct pid_namespace *ns);
@@ -72,6 +82,14 @@ static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
{
return ns;
}
+static inline struct pid_namespace *pid_ns_parent(struct pid_namespace *ns)
+{
+ return NULL;
+}
+static inline int pid_ns_level(struct pid_namespace *ns)
+{
+ return 0;
+}
static inline struct pid_namespace *copy_pid_ns(unsigned long flags,
struct user_namespace *user_ns, struct pid_namespace *ns)
diff --git a/kernel/acct.c b/kernel/acct.c
index 74963d192c5d..43e570feea45 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -569,7 +569,7 @@ void acct_collect(long exitcode, int group_dead)
static void slow_acct_process(struct pid_namespace *ns)
{
- for ( ; ns; ns = ns->parent) {
+ for ( ; ns; ns = pid_ns_parent(ns)) {
struct bsd_acct_struct *acct = acct_get(ns);
if (acct) {
do_acct_process(acct);
@@ -593,7 +593,7 @@ void acct_process(void)
* alive and holds its namespace, which in turn holds
* its parent.
*/
- for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) {
+ for (ns = task_active_pid_ns(current); ns != NULL; ns = pid_ns_parent(ns)) {
if (ns->bacct)
break;
}
diff --git a/kernel/pid.c b/kernel/pid.c
index ca368793808e..909d3dcd8085 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -76,12 +76,12 @@ struct pid_namespace init_pid_ns = {
},
.last_pid = 0,
.nr_hashed = PIDNS_HASH_ADDING,
- .level = 0,
.child_reaper = &init_task,
.user_ns = &init_user_ns,
.ns.inum = PROC_PID_INIT_INO,
#ifdef CONFIG_PID_NS
.ns.ops = &pidns_operations,
+ .level = 0,
#endif
};
EXPORT_SYMBOL_GPL(init_pid_ns);
@@ -308,8 +308,8 @@ struct pid *alloc_pid(struct pid_namespace *ns)
return ERR_PTR(retval);
tmp = ns;
- pid->level = ns->level;
- for (i = ns->level; i >= 0; i--) {
+ pid->level = pid_ns_level(ns);
+ for (i = pid_ns_level(ns); i >= 0; i--) {
nr = alloc_pidmap(tmp);
if (IS_ERR_VALUE(nr)) {
retval = nr;
@@ -318,7 +318,7 @@ struct pid *alloc_pid(struct pid_namespace *ns)
pid->numbers[i].nr = nr;
pid->numbers[i].ns = tmp;
- tmp = tmp->parent;
+ tmp = pid_ns_parent(tmp);
}
if (unlikely(is_child_reaper(pid))) {
@@ -331,7 +331,7 @@ struct pid *alloc_pid(struct pid_namespace *ns)
for (type = 0; type < PIDTYPE_MAX; ++type)
INIT_HLIST_HEAD(&pid->tasks[type]);
- upid = pid->numbers + ns->level;
+ upid = pid->numbers + pid_ns_level(ns);
spin_lock_irq(&pidmap_lock);
if (!(ns->nr_hashed & PIDNS_HASH_ADDING))
goto out_unlock;
@@ -349,7 +349,7 @@ out_unlock:
put_pid_ns(ns);
out_free:
- while (++i <= ns->level)
+ while (++i <= pid_ns_level(ns))
free_pidmap(pid->numbers + i);
kmem_cache_free(ns->pid_cachep, pid);
@@ -371,7 +371,7 @@ struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
&pid_hash[pid_hashfn(nr, ns)], pid_chain)
if (pnr->nr == nr && pnr->ns == ns)
return container_of(pnr, struct pid,
- numbers[ns->level]);
+ numbers[pid_ns_level(ns)]);
return NULL;
}
@@ -502,8 +502,8 @@ pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
struct upid *upid;
pid_t nr = 0;
- if (pid && ns->level <= pid->level) {
- upid = &pid->numbers[ns->level];
+ if (pid && pid_ns_level(ns) <= pid->level) {
+ upid = &pid->numbers[pid_ns_level(ns)];
if (upid->ns == ns)
nr = upid->nr;
}
--
2.1.3
--
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