From: David S. Miller Date: Thu, 1 Aug 2013 23:42:08 +0000 (-0700) Subject: Merge branch 'bond_rcu' X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=a594e4f8c31c400024293b2e97fc7d3faaae74da;p=openwrt%2Fstaging%2Fblogic.git Merge branch 'bond_rcu' Nikolay Aleksandrov says: ==================== This patchset aims to lay the groundwork, and do the initial conversion to RCUism. I decided that it'll be much better to make the bonding RCU conversion gradual, so patches can be reviewed and tested better rather than having one huge patch (which I did in the beginning, before this). The first patch is straightforward and it converts the bonding to the standard list API, simplifying a lot of code, removing unnecessary local variables and allowing to use the nice rculist API later. It also takes care of some minor styling issues (re-arranging local variables longest -> shortest, removing brackets for single statement if/else, leaving new line before return statement etc.). The second patch simplifies the conversion by removing unnecessary read_lock(&bond->curr_slave_lock) in xmit paths that are to be converted later, because we only care if the pointer is NULL or a slave there, since we already have bond->lock the slave can't go away. The third patch simplifies the broadcast xmit function by removing the use of curr_active_slave and converting to standard list API. Also this design of the broadcast xmit function avoids a subtle double packet tx race when converted to RCU. The fourth patch factors out the code that transmits skb through a slave with given id (i.e. rr_tx_counter in rr mode, hashed value in xor mode) and simplifies the active-backup xmit path because bond_dev_queue_xmit always consumes the skb. The new bond_xmit_slave_id function is used in rr and xor modes currently, but the plans are to use it in 3ad mode as well thus it's made global. I've left the function prototype to be 81 chars so I wouldn't break it, if this is an issue I can always break it in more lines. The fifth patch introduces RCU by converting attach/detach and release to RCU. It also converts dereferencing of curr_active_slave to rcu_dereference although it's not fully converted to RCU, that is needed for the converted xmit paths. And it converts roundrobin, broadcast, xor and active-backup xmit paths to RCU. The 3ad and ALB/TLB modes acquire read_lock(&bond->lock) to make sure that no slave will be removed and to sync properly with enslave and release as before. This way for the price of a little complexity, we'll be able to convert individual parts of the bonding to RCU, and test them easier in the process. If this patchset is accepted in some form, I'll post followups in the next weeks that gradually convert the bonding to RCU and remove the need for the rwlocks. For performance notes please refer to patch 5 (RCU conversion one). ==================== Signed-off-by: David S. Miller --- a594e4f8c31c400024293b2e97fc7d3faaae74da