Messages in this thread Patch in this message |  | | Date | Wed, 6 Feb 2013 16:55:22 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH v2] hlist: drop the node parameter from iterators |
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On Wed, 30 Jan 2013 21:00:22 -0500 Sasha Levin <sasha.levin@oracle.com> wrote:
> I'm not sure why, but the hlist for each entry iterators were conceived > differently from the list ones. While the list ones are nice and elegant: > > list_for_each_entry(pos, head, member) > > The hlist ones were greedy and wanted an extra parameter: > > hlist_for_each_entry(tpos, pos, head, member) > > Why did they need an extra pos parameter? I'm not quite sure. Not only > they don't really need it, it also prevents the iterator from looking > exactly like the list iterator, which is unfortunate. > > Besides the semantic patch, there was some manual work required: > > - Fix up the actual hlist iterators in linux/list.h > - Fix up the declaration of other iterators based on the hlist ones. > - A very small amount of places were using the 'node' parameter, this > was modified to use 'obj->member' instead. > - Coccinelle didn't handle the hlist_for_each_entry_safe iterator > properly, so those had to be fixed up manually. > > ... > > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > > ... > > @@ -4525,7 +4524,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) > * this is all done under the css_set_lock. > */ > write_lock(&css_set_lock); > - hash_for_each_safe(css_set_table, i, node, tmp, cg, hlist) { > + hash_for_each_safe(css_set_table, i, tmp, cg, hlist) { > /* skip entries that we already rehashed */ > if (cg->subsys[ss->subsys_id]) > continue;
Problems in cgroup_load_subsys().
In linux-next, that function is now using the `node' storage which your patch removes:
@@ -4503,23 +4525,17 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) * this is all done under the css_set_lock. */ write_lock(&css_set_lock); - for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { - struct css_set *cg; - struct hlist_node *node, *tmp; - struct hlist_head *bucket = &css_set_table[i], *new_bucket; - - hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { - /* skip entries that we already rehashed */ - if (cg->subsys[ss->subsys_id]) - continue; - /* remove existing entry */ - hlist_del(&cg->hlist); - /* set new value */ - cg->subsys[ss->subsys_id] = css; - /* recompute hash and restore entry */ - new_bucket = css_set_hash(cg->subsys); - hlist_add_head(&cg->hlist, new_bucket); - } + hash_for_each_safe(css_set_table, i, node, tmp, cg, hlist) { + /* skip entries that we already rehashed */ + if (cg->subsys[ss->subsys_id]) + continue; + /* remove existing entry */ + hash_del(&cg->hlist); + /* set new value */ + cg->subsys[ss->subsys_id] = css; + /* recompute hash and restore entry */ + key = css_set_hash(cg->subsys); + hash_add(css_set_table, node, key); <<<<---- here } write_unlock(&css_set_lock);
This didn't show up (apart from a "used unintialized" warning) because your patch forgot to remove the definition of `node'.
I did this. Tejun, could you please opine?
@@ -4456,7 +4455,7 @@ int __init_or_module cgroup_load_subsys( { struct cgroup_subsys_state *css; int i, ret; - struct hlist_node *node, *tmp; + struct hlist_node *tmp; struct css_set *cg; unsigned long key; @@ -4534,7 +4533,7 @@ int __init_or_module cgroup_load_subsys( cg->subsys[ss->subsys_id] = css; /* recompute hash and restore entry */ key = css_set_hash(cg->subsys); - hash_add(css_set_table, node, key); + hash_add(css_set_table, &cg->hlist, key); } write_unlock(&css_set_lock);
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