Re: [PATCH v2 5/5] net: Add Open vSwitch kernel components.

On Mon, 21 Nov 2011 15:18:43 -0800
Jesse Gross [off-list ref] wrote:

On Mon, Nov 21, 2011 at 1:59 PM, Stephen Hemminger
[off-list ref] wrote:

quoted

On Mon, 21 Nov 2011 13:30:29 -0800
Jesse Gross [off-list ref] wrote:

quoted

+/**
+ *   vport_record_error - indicate device error to generic stats layer
+ *
+ * @vport: vport that encountered the error
+ * @err_type: one of enum vport_err_type types to indicate the error type
+ *
+ * If using the vport generic stats layer indicate that an error of the given
+ * type has occured.
+ */
+void vport_record_error(struct vport *vport, enum vport_err_type err_type)
+{
+     spin_lock(&vport->stats_lock);

Sorry for over analyzing this... but I don't think the stats_lock
is necessary either. The only thing it is protecting is against 64 bit
wrap. If you used another u64_stat_sync for that one, it could be eliminated.

Maybe?

The reason for stats_lock is that the error stats are not expected to
be contended so in order to save some memory they're not per-cpu and
we just use a spin lock to protect them.

Assignment or increment of native type size (64 bit on 64 bit cpu)
is always atomic.