Date: Wed, 27 Aug 2008 01:18:32 +0200 (CEST) From: Stefan Richter Subject: ieee1394: use correct barrier types between accesses of nodeid and generation A compiler barrier (explicit on the read side, implicit on the write side) is not quite enough for what has to be accomplished here. Use hardware memory barriers on systems which need them. (Of course a full fix of generation handling would require much more than this. The ieee1394 core's bus generation counter had to be tied to the controller's bus generation counter; cf. Kristian's stack. It's just that I have other current business with the code around these barrier()s, so why not do at least this small fix.) Signed-off-by: Stefan Richter --- drivers/ieee1394/nodemgr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) Index: linux/drivers/ieee1394/nodemgr.c =================================================================== --- linux.orig/drivers/ieee1394/nodemgr.c +++ linux/drivers/ieee1394/nodemgr.c @@ -1265,7 +1265,8 @@ static void nodemgr_update_node(struct n csr1212_destroy_csr(csr); } - /* Mark the node current */ + /* Finally, mark the node current */ + smp_wmb(); ne->generation = generation; if (ne->in_limbo) { @@ -1798,7 +1799,7 @@ void hpsb_node_fill_packet(struct node_e { packet->host = ne->host; packet->generation = ne->generation; - barrier(); + smp_rmb(); packet->node_id = ne->nodeid; } @@ -1807,7 +1808,7 @@ int hpsb_node_write(struct node_entry *n { unsigned int generation = ne->generation; - barrier(); + smp_rmb(); return hpsb_write(ne->host, ne->nodeid, generation, addr, buffer, length); }