Commit 988ade6b authored Oct 14, 2009 by Krishna Kumar Committed by David S. Miller Oct 17, 2009

genetlink: Optimize and one bug fix in genl_generate_id()



1. GENL_MIN_ID is a valid id -> no need to start at
   GENL_MIN_ID + 1.
2. Avoid going through the ids two times: If we start at
   GENL_MIN_ID+1 (*or bigger*) and all ids are over!, the
   code iterates through the list twice (*or lesser*).
3. Simplify code - no need to start at idx=0 which gets
   reset to GENL_MIN_ID.

Patch on net-next-2.6. Reboot test shows that first id
passed to genl_register_family was 16, next two were
GENL_ID_GENERATE and genl_generate_id returned 17 & 18
(user level testing of same code shows expected values
across entire range of MIN/MAX).

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 93860b08

net/netlink/genetlink.c

+8 −16

Original line number	Diff line number	Diff line
		@@ -97,25 +97,17 @@ static struct genl_ops genl_get_cmd(u8 cmd, struct genl_family family)
		*/
		static inline u16 genl_generate_id(void)
		{
		static u16 id_gen_idx;
		int overflowed = 0;
		static u16 id_gen_idx = GENL_MIN_ID;
		int i;

		do {
		if (id_gen_idx == 0)
		for (i = 0; i <= GENL_MAX_ID - GENL_MIN_ID; i++) {
		if (!genl_family_find_byid(id_gen_idx))
		return id_gen_idx;
		if (++id_gen_idx > GENL_MAX_ID)
		id_gen_idx = GENL_MIN_ID;

		if (++id_gen_idx > GENL_MAX_ID) {
		if (!overflowed) {
		overflowed = 1;
		id_gen_idx = 0;
		continue;
		} else
		return 0;
		}

		} while (genl_family_find_byid(id_gen_idx));

		return id_gen_idx;
		return 0;
		}

		static struct genl_multicast_group notify_grp;