Re: [PATCH net/for-next V1 1/1] IB/ipoib: break linkage to neighbouring system
From: Or Gerlitz <hidden>
Date: 2012-07-23 16:58:21
On 20/07/2012 18:49, Or Gerlitz wrote:
On Thu, Jul 19, 2012 at 4:18 PM, Or Gerlitz[off-list ref] wrote:quoted
From: Shlomo Pongratz<shlomop-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> Dave Miller[off-list ref] provided a detailed description of why the way IPoIB is using neighbours for its own ipoib_neigh struct is buggy:[...]quoted
This patch aims to solve the race conditions found in the IPoIB driver. The patch breaks the connection between the core networking neighbour structure and the ipoib_neigh structure. Except for avoiding the race, it allows to in under a setup where SKBs carrying IP packets that don't have any associated neighbour are transmitted through IPoIB. We add an ipoib_neigh hash table with 1024 buckets. The hash table key is the destin hardware address. Thus the ipoib_neigh is fetched from the hash table and not dereferenced from the stashed location at the neighbour structure. The hash table uses both RCU and reference count mechanisms to guarantee that no ipoib_neigh instance is ever deleted while in use. Fetching the ipoib_neigh structure instance from the hash also makes the special code in ipoib_start_xmit that handles remote and local bonding failover redundant. Aged ipoib_neigh instances are deleted by a garbage collection task that runs every 30 seconds and deletes every ipoib_neigh instance that was idle for at least 60 seconds. The deletion is safe since the ipoib_neigh instances are protected using RCU and reference count mechanisms.Hi Dave, Roland, Eric So how does this look? in the right direction? anything that need to be fixed?
Sorry for the possible spam, but resending (last time forgot to put Eric on the "to" list so he might missed it, also added Christoph) - this is a fix for very long time bug in IPoIB and we do want it to be reviewed && and hopefully accepted, or if needed get feedback and fix/change. So, any further feedback? there was one feedback on V0, not to use read lock for RCU protected hash table lookup, and it was addressed in V1. Or. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html