[Devel] Re: [PATCH 1/2] Convert uid hash to hlist

[Serge E. Hallyn]

Quoting Pavel Emelyanov (xemul at openvz.org):
> Surprisingly, but (spotted by Alexey Dobriyan) the uid hash 
> still uses list_heads, thus occupying twice as much place as
> it could. Convert it to hlist_heads.
> 
> Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
> Signed-off-by: Alexey Dobriyan <adobriyan at openvz.org>
> Cc: Serge Hallyn <serue at us.ibm.com>

Looks good.

Signed-off-by: Serge Hallyn <serue at us.ibm.com>

thanks,
-serge

> 
> ---
> 
>  include/linux/sched.h          |    2 +-
>  include/linux/user_namespace.h |    2 +-
>  kernel/user.c                  |   15 ++++++++-------
>  kernel/user_namespace.c        |    2 +-
>  4 files changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index f6cf87e..a2afa88 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -535,7 +535,7 @@ struct user_struct {
>  #endif
> 
>  	/* Hash table maintenance information */
> -	struct list_head uidhash_list;
> +	struct hlist_node uidhash_node;
>  	uid_t uid;
>  };
> 
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index 1101b0c..b5f41d4 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -11,7 +11,7 @@
> 
>  struct user_namespace {
>  	struct kref		kref;
> -	struct list_head	uidhash_table[UIDHASH_SZ];
> +	struct hlist_head	uidhash_table[UIDHASH_SZ];
>  	struct user_struct	*root_user;
>  };
> 
> diff --git a/kernel/user.c b/kernel/user.c
> index e080ba8..add57c7 100644
> --- a/kernel/user.c
> +++ b/kernel/user.c
> @@ -55,21 +55,22 @@ struct user_struct root_user = {
>  /*
>   * These routines must be called with the uidhash spinlock held!
>   */
> -static inline void uid_hash_insert(struct user_struct *up, struct list_head *hashent)
> +static inline void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
>  {
> -	list_add(&up->uidhash_list, hashent);
> +	hlist_add_head(&up->uidhash_node, hashent);
>  }
> 
>  static inline void uid_hash_remove(struct user_struct *up)
>  {
> -	list_del(&up->uidhash_list);
> +	hlist_del(&up->uidhash_node);
>  }
> 
> -static inline struct user_struct *uid_hash_find(uid_t uid, struct list_head *hashent)
> +static inline struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
>  {
>  	struct user_struct *user;
> +	struct hlist_node *h;
> 
> -	list_for_each_entry(user, hashent, uidhash_list) {
> +	hlist_for_each_entry(user, h, hashent, uidhash_node) {
>  		if(user->uid == uid) {
>  			atomic_inc(&user->__count);
>  			return user;
> @@ -118,7 +119,7 @@ void free_uid(struct user_struct *up)
> 
>  struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
>  {
> -	struct list_head *hashent = uidhashentry(ns, uid);
> +	struct hlist_head *hashent = uidhashentry(ns, uid);
>  	struct user_struct *up;
> 
>  	spin_lock_irq(&uidhash_lock);
> @@ -207,7 +208,7 @@ static int __init uid_cache_init(void)
>  			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
> 
>  	for(n = 0; n < UIDHASH_SZ; ++n)
> -		INIT_LIST_HEAD(init_user_ns.uidhash_table + n);
> +		INIT_HLIST_HEAD(init_user_ns.uidhash_table + n);
> 
>  	/* Insert the root user immediately (init already runs as root) */
>  	spin_lock_irq(&uidhash_lock);
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index df1d2cf..7af90fc 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -39,7 +39,7 @@ static struct user_namespace *clone_user
>  	kref_init(&ns->kref);
> 
>  	for (n = 0; n < UIDHASH_SZ; ++n)
> -		INIT_LIST_HEAD(ns->uidhash_table + n);
> +		INIT_HLIST_HEAD(ns->uidhash_table + n);
> 
>  	/* Insert new root user.  */
>  	ns->root_user = alloc_uid(ns, 0);