[ovs-dev] [PATCH 09/10] datapath: Allocate vports in more RCU friendly manner.

Ben Pfaff blp at nicira.com
Wed Dec 29 18:19:40 UTC 2010


On Tue, Dec 28, 2010 at 08:50:47PM -0800, Jesse Gross wrote:
> In a few places, when creating a new vport we also need to allocate
> some memory for configuration that can change.  This data is protected
> by RCU but we directly access the memory when initializing it.  This
> is fine, since the vport has not yet been published and we use the
> apropriate memory barriers when doing so.  However, it makes tools
> like sparse unhappy and is also asymmetric since we use RCU to
> derefence the pointers but not to assign them.  This cleans that

"dereference"

> up somewhat by initializing the memory first and then using RCU
> to assign it, which makes everyone happy.
> 
> Found with sparse.
> 
> Signed-off-by: Jesse Gross <jesse at nicira.com>

Acked-by: Ben Pfaff <blp at nicira.com>




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