Drivers: hv: Eliminate the channel spinlock in the callback path
By ensuring that we set the callback handler to NULL in the channel close
path on the same CPU that the channel is bound to, we can eliminate this lock
acquisition and release in a performance critical path.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index fa92046..6f7fdd9 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -365,7 +365,7 @@
* performance critical channels (IDE, SCSI and Network) will be uniformly
* distributed across all available CPUs.
*/
-static u32 get_vp_index(uuid_le *type_guid)
+static void init_vp_index(struct vmbus_channel *channel, uuid_le *type_guid)
{
u32 cur_cpu;
int i;
@@ -387,10 +387,13 @@
* Also if the channel is not a performance critical
* channel, bind it to cpu 0.
*/
- return 0;
+ channel->target_cpu = 0;
+ channel->target_vp = 0;
+ return;
}
cur_cpu = (++next_vp % max_cpus);
- return hv_context.vp_index[cur_cpu];
+ channel->target_cpu = cur_cpu;
+ channel->target_vp = hv_context.vp_index[cur_cpu];
}
/*
@@ -438,7 +441,7 @@
offer->connection_id;
}
- newchannel->target_vp = get_vp_index(&offer->offer.if_type);
+ init_vp_index(newchannel, &offer->offer.if_type);
memcpy(&newchannel->offermsg, offer,
sizeof(struct vmbus_channel_offer_channel));