Re: [PATCH -next] rcu: remove INIT_RCU_HEAD, RCU_HEAD_INIT, RCU_HEAD

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Sun, Feb 21, 2010 at 05:26:45PM +0200, Alexey Dobriyan wrote:
> call_rcu() will unconditionally reinitialize RCU head anyway.
> New users of these macros constantly appear, so remove them.

Some people have used these for debugging purposes, but I guess that
they could use kmem_zalloc() and friends to get the same effect. So:

Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> ---
> 
>  Documentation/DocBook/kernel-locking.tmpl   |    8 --------
>  arch/powerpc/mm/pgtable.c                   |    1 -
>  block/cfq-iosched.c                         |    1 -
>  block/genhd.c                               |    1 -
>  drivers/staging/batman-adv/hard-interface.c |    1 -
>  fs/file.c                                   |    3 ---
>  fs/fs-writeback.c                           |    1 -
>  fs/partitions/check.c                       |    1 -
>  include/linux/init_task.h                   |    1 -
>  include/linux/rcupdate.h                    |    6 ------
>  mm/backing-dev.c                            |    1 -
>  mm/slob.c                                   |    1 -
>  security/selinux/avc.c                      |    1 -
>  security/selinux/netnode.c                  |    2 --
>  14 files changed, 29 deletions(-)
> 
> --- a/Documentation/DocBook/kernel-locking.tmpl
> +++ b/Documentation/DocBook/kernel-locking.tmpl
> @@ -1725,14 +1725,6 @@ the amount of locking which needs to be done.
>           if (++cache_num > MAX_CACHE_SIZE) {
>                   struct object *i, *outcast = NULL;
>                   list_for_each_entry(i, &amp;cache, list) {
> -@@ -85,6 +94,7 @@
> -         obj-&gt;popularity = 0;
> -         atomic_set(&amp;obj-&gt;refcnt, 1); /* The cache holds a reference */
> -         spin_lock_init(&amp;obj-&gt;lock);
> -+        INIT_RCU_HEAD(&amp;obj-&gt;rcu);
> -
> -         spin_lock_irqsave(&amp;cache_lock, flags);
> -         __cache_add(obj);
>  @@ -104,12 +114,11 @@
>   struct object *cache_find(int id)
>   {
> --- a/arch/powerpc/mm/pgtable.c
> +++ b/arch/powerpc/mm/pgtable.c
> @@ -91,7 +91,6 @@ static void pte_free_rcu_callback(struct rcu_head *head)
> 
>  static void pte_free_submit(struct pte_freelist_batch *batch)
>  {
> -	INIT_RCU_HEAD(&batch->rcu);
>  	call_rcu(&batch->rcu, pte_free_rcu_callback);
>  }
> 
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -3730,7 +3730,6 @@ static void *cfq_init_queue(struct request_queue *q)
>  	 * second, in order to have larger depth for async operations.
>  	 */
>  	cfqd->last_delayed_sync = jiffies - HZ;
> -	INIT_RCU_HEAD(&cfqd->rcu);
>  	return cfqd;
>  }
> 
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -987,7 +987,6 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno)
>  	if (!new_ptbl)
>  		return -ENOMEM;
> 
> -	INIT_RCU_HEAD(&new_ptbl->rcu_head);
>  	new_ptbl->len = target;
> 
>  	for (i = 0; i < len; i++)
> --- a/drivers/staging/batman-adv/hard-interface.c
> +++ b/drivers/staging/batman-adv/hard-interface.c
> @@ -301,7 +301,6 @@ int hardif_add_interface(char *dev, int if_num)
>  	batman_if->if_num = if_num;
>  	batman_if->dev = dev;
>  	batman_if->if_active = IF_INACTIVE;
> -	INIT_RCU_HEAD(&batman_if->rcu);
> 
>  	printk(KERN_INFO "batman-adv:Adding interface: %s\n", dev);
>  	avail_ifs++;
> --- a/fs/file.c
> +++ b/fs/file.c
> @@ -178,7 +178,6 @@ static struct fdtable * alloc_fdtable(unsigned int nr)
>  	fdt->open_fds = (fd_set *)data;
>  	data += nr / BITS_PER_BYTE;
>  	fdt->close_on_exec = (fd_set *)data;
> -	INIT_RCU_HEAD(&fdt->rcu);
>  	fdt->next = NULL;
> 
>  	return fdt;
> @@ -312,7 +311,6 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
>  	new_fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
>  	new_fdt->open_fds = (fd_set *)&newf->open_fds_init;
>  	new_fdt->fd = &newf->fd_array[0];
> -	INIT_RCU_HEAD(&new_fdt->rcu);
>  	new_fdt->next = NULL;
> 
>  	spin_lock(&oldf->file_lock);
> @@ -430,7 +428,6 @@ struct files_struct init_files = {
>  		.fd		= &init_files.fd_array[0],
>  		.close_on_exec	= (fd_set *)&init_files.close_on_exec_init,
>  		.open_fds	= (fd_set *)&init_files.open_fds_init,
> -		.rcu		= RCU_HEAD_INIT,
>  	},
>  	.file_lock	= __SPIN_LOCK_UNLOCKED(init_task.file_lock),
>  };
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -77,7 +77,6 @@ static inline bool bdi_work_on_stack(struct bdi_work *work)
>  static inline void bdi_work_init(struct bdi_work *work,
>  				 struct wb_writeback_args *args)
>  {
> -	INIT_RCU_HEAD(&work->rcu_head);
>  	work->args = *args;
>  	work->state = WS_USED;
>  }
> --- a/fs/partitions/check.c
> +++ b/fs/partitions/check.c
> @@ -455,7 +455,6 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
>  	}
> 
>  	/* everything is up and running, commence */
> -	INIT_RCU_HEAD(&p->rcu_head);
>  	rcu_assign_pointer(ptbl->part[partno], p);
> 
>  	/* suppress uevent if the disk supresses it */
> --- a/include/linux/init_task.h
> +++ b/include/linux/init_task.h
> @@ -57,7 +57,6 @@ extern struct group_info init_groups;
>  		{ .first = &init_task.pids[PIDTYPE_PGID].node },	\
>  		{ .first = &init_task.pids[PIDTYPE_SID].node },		\
>  	},								\
> -	.rcu		= RCU_HEAD_INIT,				\
>  	.level		= 0,						\
>  	.numbers	= { {						\
>  		.nr		= 0,					\
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -71,12 +71,6 @@ extern void rcu_init(void);
>  #error "Unknown RCU implementation specified to kernel configuration"
>  #endif
> 
> -#define RCU_HEAD_INIT	{ .next = NULL, .func = NULL }
> -#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT
> -#define INIT_RCU_HEAD(ptr) do { \
> -       (ptr)->next = NULL; (ptr)->func = NULL; \
> -} while (0)
> -
>  #ifdef CONFIG_DEBUG_LOCK_ALLOC
>  extern struct lockdep_map rcu_lock_map;
>  # define rcu_read_acquire()	\
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -655,7 +655,6 @@ int bdi_init(struct backing_dev_info *bdi)
>  	bdi->max_ratio = 100;
>  	bdi->max_prop_frac = PROP_FRAC_BASE;
>  	spin_lock_init(&bdi->wb_lock);
> -	INIT_RCU_HEAD(&bdi->rcu_head);
>  	INIT_LIST_HEAD(&bdi->bdi_list);
>  	INIT_LIST_HEAD(&bdi->wb_list);
>  	INIT_LIST_HEAD(&bdi->work_list);
> --- a/mm/slob.c
> +++ b/mm/slob.c
> @@ -647,7 +647,6 @@ void kmem_cache_free(struct kmem_cache *c, void *b)
>  	if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {
>  		struct slob_rcu *slob_rcu;
>  		slob_rcu = b + (c->size - sizeof(struct slob_rcu));
> -		INIT_RCU_HEAD(&slob_rcu->head);
>  		slob_rcu->size = c->size;
>  		call_rcu(&slob_rcu->head, kmem_rcu_free);
>  	} else {
> --- a/security/selinux/avc.c
> +++ b/security/selinux/avc.c
> @@ -288,7 +288,6 @@ static struct avc_node *avc_alloc_node(void)
>  	if (!node)
>  		goto out;
> 
> -	INIT_RCU_HEAD(&node->rhead);
>  	INIT_HLIST_NODE(&node->list);
>  	avc_cache_stats_incr(allocations);
> 
> --- a/security/selinux/netnode.c
> +++ b/security/selinux/netnode.c
> @@ -182,8 +182,6 @@ static void sel_netnode_insert(struct sel_netnode *node)
>  		BUG();
>  	}
> 
> -	INIT_RCU_HEAD(&node->rcu);
> -
>  	/* we need to impose a limit on the growth of the hash table so check
>  	 * this bucket to make sure it is within the specified bounds */
>  	list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
> --
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