[PATCH 2/3] netlink: use vzalloc()

[PATCH 2/3] netlink: use vzalloc()

[Stephen Hemminger]

The netlink pid hash can be allocated using vzalloc() rather than direct
access to get_free_pages. It is also safe for nl_pid_hash_zalloc to use
GFP_KERNEL since it is only called from netlink_proto_init and
nl_pid_hash_rehash. The former is already allocating table with GFP_KERNEL,
and the latter is called from netlink_insert() which already could 
sleep in netlink_table_grab()

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

--- a/net/netlink/af_netlink.c	2011-12-20 10:20:33.356914405 -0800
+++ b/net/netlink/af_netlink.c	2011-12-20 10:25:19.364247598 -0800
@@ -251,11 +251,9 @@ found:
 static struct hlist_head *nl_pid_hash_zalloc(size_t size)
 {
 	if (size <= PAGE_SIZE)
-		return kzalloc(size, GFP_ATOMIC);
+		return kzalloc(size, GFP_KERNEL);
 	else
-		return (struct hlist_head *)
-			__get_free_pages(GFP_ATOMIC | __GFP_ZERO,
-					 get_order(size));
+		return vzalloc(size);
 }
 
 static void nl_pid_hash_free(struct hlist_head *table, size_t size)
@@ -263,7 +261,7 @@ static void nl_pid_hash_free(struct hlis
 	if (size <= PAGE_SIZE)
 		kfree(table);
 	else
-		free_pages((unsigned long)table, get_order(size));
+		vfree(table);
 }
 
 static int nl_pid_hash_rehash(struct nl_pid_hash *hash, int grow)

Re: [PATCH 2/3] netlink: use vzalloc()

[Eric Dumazet]

Le mercredi 21 décembre 2011 à 13:48 -0800, Stephen Hemminger a écrit :
> The netlink pid hash can be allocated using vzalloc() rather than direct
> access to get_free_pages. It is also safe for nl_pid_hash_zalloc to use
> GFP_KERNEL since it is only called from netlink_proto_init and
> nl_pid_hash_rehash. The former is already allocating table with GFP_KERNEL,
> and the latter is called from netlink_insert() which already could 
> sleep in netlink_table_grab()
> 


But netlink_table_grab() returns with write_lock_irq(&nl_table_lock);

So we are not allowed to sleep in a
netlink_table_grab()/netlink_table_ungrab() section .

Re: [PATCH 2/3] netlink: use vzalloc()

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 21 Dec 2011 23:12:31 +0100

> Le mercredi 21 décembre 2011 à 13:48 -0800, Stephen Hemminger a écrit :
>> The netlink pid hash can be allocated using vzalloc() rather than direct
>> access to get_free_pages. It is also safe for nl_pid_hash_zalloc to use
>> GFP_KERNEL since it is only called from netlink_proto_init and
>> nl_pid_hash_rehash. The former is already allocating table with GFP_KERNEL,
>> and the latter is called from netlink_insert() which already could 
>> sleep in netlink_table_grab()
>> 
> 
> 
> But netlink_table_grab() returns with write_lock_irq(&nl_table_lock);
> 
> So we are not allowed to sleep in a
> netlink_table_grab()/netlink_table_ungrab() section .

Right.